Dynamic eQTL analysis on iPSC

workflowr

• Summary
• Checks
• Past versions

Last updated: 2025-12-12

Checks: 7 0

Knit directory: fashr-paper-stephenslab/

This reproducible R Markdown analysis was created with workflowr (version 1.7.2). The Checks tab describes the reproducibility checks that were applied when the results were created. The Past versions tab lists the development history.

---

R Markdown file: up-to-date

Great! Since the R Markdown file has been committed to the Git repository, you know the exact version of the code that produced these results.

Environment: empty

Great job! The global environment was empty. Objects defined in the global environment can affect the analysis in your R Markdown file in unknown ways. For reproduciblity it’s best to always run the code in an empty environment.

Seed: set.seed(20251109)

The command set.seed(20251109) was run prior to running the code in the R Markdown file. Setting a seed ensures that any results that rely on randomness, e.g. subsampling or permutations, are reproducible.

Session information: recorded

Great job! Recording the operating system, R version, and package versions is critical for reproducibility.

Cache: none

Nice! There were no cached chunks for this analysis, so you can be confident that you successfully produced the results during this run.

File paths: relative

Great job! Using relative paths to the files within your workflowr project makes it easier to run your code on other machines.

Repository version: bb505cf

Great! You are using Git for version control. Tracking code development and connecting the code version to the results is critical for reproducibility.

The results in this page were generated with repository version bb505cf. See the Past versions tab to see a history of the changes made to the R Markdown and HTML files.

Note that you need to be careful to ensure that all relevant files for the analysis have been committed to Git prior to generating the results (you can use wflow_publish or wflow_git_commit). workflowr only checks the R Markdown file, but you know if there are other scripts or data files that it depends on. Below is the status of the Git repository when the results were generated:

Ignored files:
    Ignored:    .DS_Store
    Ignored:    .Rhistory
    Ignored:    .Rproj.user/
    Ignored:    data/.DS_Store
    Ignored:    data/toy_example/
    Ignored:    output/.DS_Store

Untracked files:
    Untracked:  code/00_eQTLs.R
    Untracked:  code/01_fash.R
    Untracked:  code/01_fash_uncorrected.R
    Untracked:  code/02_dyn.R
    Untracked:  code/03_nonlindyn.R
    Untracked:  code/04_minlfsr.R
    Untracked:  code/05_Interact.R
    Untracked:  code/06_minlfsr_nonlin.R
    Untracked:  code/07_grid_sensitivity.R
    Untracked:  code/08_grid_sensitivity.R
    Untracked:  code/filterVariantPerGene.R
    Untracked:  data/appendixB/
    Untracked:  data/dynamic_eQTL_real/
    Untracked:  output/appendixB/
    Untracked:  output/dynamic_eQTL_real/
    Untracked:  output/toy_example/

Note that any generated files, e.g. HTML, png, CSS, etc., are not included in this status report because it is ok for generated content to have uncommitted changes.

---

These are the previous versions of the repository in which changes were made to the R Markdown (analysis/dynamic_eQTL_real.rmd) and HTML (docs/dynamic_eQTL_real.html) files. If you’ve configured a remote Git repository (see ?wflow_git_remote), click on the hyperlinks in the table below to view the files as they were in that past version.

File	Version	Author	Date	Message
Rmd	bb505cf	Ziang Zhang	2025-12-12	workflowr::wflow_publish("analysis/dynamic_eQTL_real.rmd")
html	83145cc	Ziang Zhang	2025-12-12	Build site.
Rmd	aae2964	Ziang Zhang	2025-12-12	workflowr::wflow_publish("analysis/dynamic_eQTL_real.rmd")
html	36a81a3	Ziang Zhang	2025-11-09	Build site.
html	d73f3f1	Ziang Zhang	2025-11-09	Build site.
Rmd	9f55956	Ziang Zhang	2025-11-09	workflowr::wflow_publish("analysis/dynamic_eQTL_real.rmd")

---

knitr::opts_chunk$set(fig.width = 8, fig.height = 6)
library(fashr)
library(biomaRt)
mart <- useEnsembl(biomart = "genes", dataset = "hsapiens_gene_ensembl")
result_dir <- paste0(getwd(), "/output/dynamic_eQTL_real")
data_dir <- paste0(getwd(), "/data/dynamic_eQTL_real")
code_dir <- paste0(getwd(), "/code/dynamic_eQTL_real")
log_prec <- seq(0,10, by = 0.2)
fine_grid <- sort(c(0, exp(-0.5*log_prec)))

Obtain the effect size of eQTLs

We use the processed (expression & genotype) data of Strober et.al, 2019 to perform the eQTL analysis.

For the association testing, we use a linear regression model for each gene-variant pair at each time point. Following the practice in Strober et.al, we adjust for the first five PCs.

The code to perform this step can be found in the script dynamic_eQTL_real/00_eQTLs.R from the code directory.

After this step, we have the effect size of eQTLs for each gene-variant pair at each time point, as well as its standard error.

Fitting FASH

To fit the FASH model on \(\{\beta_i(t_j), s_{ij}\}_{i\in N,j \in [16]}\), we consider fitting two FASH models:

• A FASH model based on first order IWP (testing for dynamic eQTLs: \(H_0: \beta_i(t)=c\)).

• A FASH model based on second order IWP (testing for nonlinear-dynamic eQTLs: \(H_0: \beta_i(t)=c_1+c_2t\)).

The code to perform this step can be found in the script dynamic_eQTL_real/01_fash.R from the code directory.

We will directly load the fitted FASH models from the output directory.

load(paste0(result_dir, "/fash_fit1_all.RData"))

We will load the datasets from the fitted FASH object:

datasets <- fash_fit1$fash_data$data_list
for (i in 1:length(datasets)) {
  datasets[[i]]$SE <- fash_fit1$fash_data$S[[i]]
}
all_genes <- unique(sapply(strsplit(names(datasets), "_"), "[[", 1))
full_map <- getBM(
  attributes = c("hgnc_symbol", "ensembl_gene_id"),
  filters    = "ensembl_gene_id",
  values     = all_genes,
  mart       = mart
)

In this analysis, we will focus on the FASH(1) model that assumes a first order IWP and tests for dynamic eQTLs.

Let’s take a quick overview of the fitted FASH model:

log_prec <- seq(0,10, by = 0.2)
fine_grid <- sort(c(0, exp(-0.5*log_prec)))

fash_fit1 <- fash(Y = "beta", smooth_var = "time", S = "SE", data_list = datasets,
                  num_basis = 20, order = 1, betaprec = 0,
                  pred_step = 1, penalty = 10, grid = fine_grid,
                  num_cores = num_cores, verbose = TRUE)
save(fash_fit1, file = "./results/fash_fit1_all.RData")

fash_fit1

Fitted fash Object
-------------------
Number of datasets: 1009173
Likelihood: gaussian
Number of PSD grid values: 52 (initial), 11 (non-trivial)
Order of Integrated Wiener Process (IWP): 1

As well as the estimated priors:

fash_fit1$prior_weights

           psd prior_weight
1  0.000000000  0.410663695
2  0.006737947  0.141127785
3  0.016572675  0.012015292
4  0.049787068  0.178001757
5  0.074273578  0.071560569
6  0.110803158  0.098258453
7  0.182683524  0.037970329
8  0.246596964  0.021572272
9  0.367879441  0.007501801
10 0.406569660  0.011455909
11 1.000000000  0.009872138

Problem with \(\pi_0\) estimation

If we measure the significance using the false discovery rate, then it is sensitive to the value of \(\pi_0\). The estimated \(\pi_0\) is 0.4106637, which is way too small to be realistic.

One likely reason could be due to model-misspecification under the alternative hypothesis. To account for this, we will consider the following approaches:

(i): Computing a conservative estimate of \(\pi_0\) based on the BF procedure:

fash_fit1_update <- BF_update(fash_fit1, plot = FALSE)
fash_fit1_update$prior_weights
save(fash_fit1_update, file = paste0(result_dir, "/fash_fit1_update.RData"))

The conservative estimate is 0.93568, which is much more realistic.

(ii): Instead of looking at the FDR which is based on the estimated \(\pi_0\), we can use the minimum local false sign rate (\(\text{min-lfsr}_i\)) to measure significance: \[ \text{min-lfsr}_i = \min_{t} \left\{ \text{lfsr}(W_i(t)) \right\}, \] where \(W_i(t) = \beta_i(t) - \beta_i(0)\).

Let’s compute the significance using the minimum local false sign rate (\(\text{min-lfsr}_i\)):

smooth_var_refined = seq(0,15, by = 0.1)
min_lfsr_summary1 <- min_lfsr_summary(fash_fit1, num_cores = num_cores, smooth_var = smooth_var_refined)
save(min_lfsr_summary1, file = "./results/min_lfsr_summary1.RData")
min_lfsr_summary1_update <- min_lfsr_summary(fash_fit1_update, num_cores = num_cores, smooth_var = smooth_var_refined)
save(min_lfsr_summary1_update, file = "./results/min_lfsr_summary1_update.RData")

Let’s visualize how the min-lfsr compares with the local false discovery rate (lfdr):

load(paste0(result_dir, "/min_lfsr_summary1.RData"))
# sample some indices for easy visualization
sample_indices <- sample(1:length(min_lfsr_summary1$min_lfsr), 1e5)
min_lfsr1_unadj <- min_lfsr_summary1$min_lfsr[sample_indices]
lfdr1_vec_unadj <- fash_fit1$lfdr[min_lfsr_summary1$index][sample_indices]
plot(lfdr1_vec_unadj, min_lfsr1_unadj, 
     pch = 20, cex = 0.1,
     ylim = c(0,1), xlim = c(0,1),
     xlab = "lfdr", ylab = "min-lfsr", main = "lfdr vs min-lfsr (Un-adjusted)")
lines(c(0,1), c(0,1), col = "red")

Past versions of unnamed-chunk-9-1.png

Version	Author	Date
d73f3f1	Ziang Zhang	2025-11-09

Let’s also visualize the min-lfsr and the lfdr from the BF-updated model:

load(paste0(result_dir, "/min_lfsr_summary1_update.RData"))
min_lfsr1 <- min_lfsr_summary1_update$min_lfsr[sample_indices]
lfdr1_vec <- fash_fit1_update$lfdr[min_lfsr_summary1_update$index[sample_indices]]
plot(lfdr1_vec, min_lfsr1, 
     pch = 20, cex = 0.1,
     ylim = c(0,1), xlim = c(0,1),
     xlab = "lfdr", ylab = "min-lfsr", main = "lfdr vs min-lfsr (BF-adjusted)")
lines(c(0,1), c(0,1), col = "red")

Past versions of unnamed-chunk-10-1.png

Version	Author	Date
d73f3f1	Ziang Zhang	2025-11-09

Indeed, the min-lfsr tends to be more conservative than the lfdr, especially when \(\hat{\pi_0}\) has not been adjusted using the BF procedure.

Let’s also assess how does the BF-update of \(\pi_0\) affect the min-lfsr.

plot(min_lfsr1_unadj, min_lfsr1, 
     pch = 20, cex = 0.1,
     ylim = c(0,1), xlim = c(0,1),
     xlab = "min-lfsr (unadjusted)", ylab = "min-lfsr", main = "Effect of BF adjustment on min-lfsr")
lines(c(0,1), c(0,1), col = "red")

Past versions of unnamed-chunk-11-1.png

Version	Author	Date
d73f3f1	Ziang Zhang	2025-11-09

Detecting dynamic eQTLs

We will use the updated FASH model (1) to detect dynamic eQTLs.

alpha <- 0.05
test1 <- fdr_control(fash_fit1_update, alpha = alpha, plot = F)

10290 datasets are significant at alpha level 0.05. Total datasets tested: 1009173. 

fash_highlighted1 <- test1$fdr_results$index[test1$fdr_results$FDR <= alpha]

test1_before <- fdr_control(fash_fit1, alpha = alpha, plot = F)

50027 datasets are significant at alpha level 0.05. Total datasets tested: 1009173. 

fash_highlighted1_before <- test1_before$fdr_results$index[test1_before$fdr_results$FDR <= alpha]

How many pairs are detected as dynamic eQTLs?

pairs_highlighted1 <- names(datasets)[fash_highlighted1]
length(pairs_highlighted1)

[1] 10290

length(pairs_highlighted1)/length(datasets)

[1] 0.01019647

What is the number before the BF adjustment?

pairs_highlighted1_before <- names(datasets)[fash_highlighted1_before]
length(pairs_highlighted1_before)

[1] 50027

length(pairs_highlighted1_before)/length(datasets)

[1] 0.04957227

How many unique genes are detected?

genes_highlighted1 <- unique(sapply(strsplit(pairs_highlighted1, "_"), "[[", 1))
length(genes_highlighted1)

[1] 1295

length(genes_highlighted1)/length(all_genes)

[1] 0.2035523

Before the BF adjustment?

genes_highlighted1_before <- unique(sapply(strsplit(pairs_highlighted1_before, "_"), "[[", 1))
length(genes_highlighted1_before)

[1] 3417

length(genes_highlighted1_before)/length(all_genes)

[1] 0.5370953

Let’s see how many pairs and genes remain significant after controlling the min-lfsr:

fash_highlighted1_lfsr <- min_lfsr_summary1_update$index[min_lfsr_summary1_update$fsr <= alpha]
pairs_highlighted1_lfsr <- names(datasets)[fash_highlighted1_lfsr]
length(pairs_highlighted1_lfsr)

[1] 10070

length(pairs_highlighted1_lfsr)/length(datasets)

[1] 0.009978468

genes_highlighted1_lfsr <- unique(sapply(strsplit(pairs_highlighted1_lfsr, "_"), "[[", 1))
length(genes_highlighted1_lfsr)

[1] 1271

length(genes_highlighted1_lfsr)/length(all_genes)

[1] 0.1997799

It seems like once \(\hat{\pi_0}\) is adjusted, there is not much difference between measuring significance using the min-lfsr or the lfdr. From now on, we will consider the pairs that are significant using the lfdr.

Visualize top-ranked pairs for some selected genes:

Past versions of unnamed-chunk-19-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

Visualize some genes highlighted in the original analysis:

highlights <- paste0("ENSG00000183873", c("_rs7633988", "_rs6599234"))
par(mfrow = c(2,2))
for (i in seq_along(highlights)) {
  selected_index <- which(highlights[i] == names(datasets))

  ## shorthand
  x  <- datasets[[selected_index]]$x
  y  <- datasets[[selected_index]]$y
  se <- datasets[[selected_index]]$SE
  w  <- 1 / (se^2)  # precision weights

  y_min <- min(y - 2 * se)
  y_max <- max(y + 2 * se)

  # weighted mean
  y_wmean <- sum(y * w) / sum(w)

  # weighted linear fit
  lin_fit <- lm(y ~ x, weights = w)

  # weighted quadratic fit
  quad_fit <- lm(y ~ poly(x, 2, raw = TRUE), weights = w)
  x_grid   <- seq(min(x), max(x), length.out = 200)
  quad_pred <- predict(quad_fit, newdata = data.frame(x = x_grid))

  ## --------------------------
  ## 1) BEFORE BF adjustment
  ## --------------------------
  fitted_result_before <- predict(
    fash_fit1,                         
    index      = selected_index,
    smooth_var = seq(0, 15, by = 0.1)
  )

  plot(
    x, y,
    pch  = 20,
    col  = "black",
    xlab = "Time",
    ylab = "Effect Est",
    # main = names(datasets)[selected_index],
    ylim = c(y_min, y_max)
  )
  variant_id <- strsplit(names(datasets)[selected_index], "_")[[1]][2]
  gene_symbol <- map$hgnc_symbol[map$ensembl_gene_id == "ENSG00000183873"]
  title(main = paste0(gene_symbol, ": ", variant_id))
  arrows(
    x0 = x,
    y0 = y - 2 * se,
    x1 = x,
    y1 = y + 2 * se,
    length = 0.05,
    angle  = 90,
    code   = 3,
    col    = "black"
  )

  # credible band first
  polygon(
    c(fitted_result_before$x, rev(fitted_result_before$x)),
    c(fitted_result_before$lower, rev(fitted_result_before$upper)),
    col    = rgb(1, 0, 0, 0.3),
    border = NA
  )

  # posterior mean curve
  lines(
    fitted_result_before$x,
    fitted_result_before$mean,
    col = "red",
    lwd = 2
  )

  # # weighted average line
  # abline(h = y_wmean, col = "blue", lty = 2)

  # weighted linear fit (straight line)
  abline(lin_fit, col = "green", lty = 2, lwd = 1)

  # weighted quadratic fit (curve)
  lines(x_grid, quad_pred, col = "purple", lty = 2, lwd = 1)

  # text for caption
  caption <- sprintf("lfdr (raw) = %.3f",
                     lfdr_before)
  
  # add caption as subtitle
  title(sub = caption, cex.sub = 0.8)

  ## --------------------------
  ## 2) AFTER BF adjustment
  ## --------------------------
  fitted_result_after <- predict(
    fash_fit1_update,                  # updated fit
    index      = selected_index,
    smooth_var = seq(0, 15, by = 0.1)
  )

  plot(
    x, y,
    pch  = 20,
    col  = "black",
    xlab = "Time",
    ylab = "Effect Est",
    # main = names(datasets)[selected_index],
    ylim = c(y_min, y_max)
  )
  
  title(main = paste0(gene_symbol, ": ", variant_id))

  arrows(
    x0 = x,
    y0 = y - 2 * se,
    x1 = x,
    y1 = y + 2 * se,
    length = 0.05,
    angle  = 90,
    code   = 3,
    col    = "black"
  )

  polygon(
    c(fitted_result_after$x, rev(fitted_result_after$x)),
    c(fitted_result_after$lower, rev(fitted_result_after$upper)),
    col    = rgb(1, 0, 0, 0.3),
    border = NA
  )

  lines(
    fitted_result_after$x,
    fitted_result_after$mean,
    col = "red",
    lwd = 2
  )

  # reuse the same weighted summaries/fits
  # abline(h = y_wmean, col = "blue",  lty = 2)
  abline(lin_fit,     col = "green", lty = 1)
  lines(x_grid, quad_pred, col = "purple", lty = 2, lwd = 1)
  
    # lfdr before and after
  lfdr_before <- fash_fit1$lfdr[selected_index]
  lfdr_after  <- fash_fit1_update$lfdr[selected_index]
  
  # text for caption
  caption <- sprintf("lfdr (adj) = %.3f",
                     lfdr_after)
  
  # add caption as subtitle
  title(sub = caption, cex.sub = 0.8)
  
}

Past versions of unnamed-chunk-20-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12
d73f3f1	Ziang Zhang	2025-11-09

par(mfrow = c(1,1))

These examples were highlighted using the un-adjusted FASH model, but not significant after the BF adjustment.

Take a look at the most significant variants for the gene ‘ENSG00000183873’:

# get the indices of the highlighted pairs for ENSG00000183873
SCN5A_pairs <- pairs_highlighted1[grep("ENSG00000183873", names(datasets)[fash_highlighted1])]
# pick the most significant four variants
all_selected_indices <- fash_highlighted1[grep("ENSG00000183873", names(datasets)[fash_highlighted1])]
lfdr_values <- fash_fit1_update$lfdr[all_selected_indices]
selected_indices <- all_selected_indices[order(lfdr_values)][1:4]
# plot
par(mfrow = c(2,2))
for (selected_index in selected_indices) {
  # shorthand 
  x  <- datasets[[selected_index]]$x
  y  <- datasets[[selected_index]]$y
  se <- datasets[[selected_index]]$SE
  w  <- 1 / (se^2)
  y_min <- min(y - 2 * se)
  y_max <- max(y + 2 * se)
  # weighted mean
  y_wmean <- sum(y * w) / sum(w)
  # weighted linear fit
  lin_fit <- lm(y ~ x, weights = w)
  # weighted quadratic fit
  quad_fit  <- lm(y ~ poly(x, 2, raw = TRUE), weights = w)
  x_grid    <- seq(min(x), max(x), length.out = 200)
  quad_pred <- predict(quad_fit, newdata = data.frame(x = x_grid))
  # FASH fit (after adjustment)
  fitted_result <- predict(
    fash_fit1_update,
    index      = selected_index,
    smooth_var = seq(0, 15, by = 0.1)
  )
  plot(
    x, y,
    pch  = 20,
    col  = "black",
    xlab = "Time",
    ylab = "Effect Est",
    # main = names(datasets)[selected_index],
    ylim = c(y_min, y_max)
  )
  variant_id <- strsplit(names(datasets)[selected_index], "_")[[1]][2]
  gene_symbol <- full_map$hgnc_symbol[full_map$ensembl_gene_id == "ENSG00000183873"]
  title(main = paste0(gene_symbol, ": ", variant_id))
  arrows(
    x0 = x,
    y0 = y - 2 * se,
    x1 = x,
    y1 = y + 2 * se,
    length = 0.05,
    angle  = 90,
    code   = 3,
    col    = "black"
  )
  polygon(
    c(fitted_result$x, rev(fitted_result$x)),
    c(fitted_result$lower, rev(fitted_result$upper)),
    col    = rgb(1, 0, 0, 0.3),
    border = NA
  )
  # posterior mean curve
  lines(
    fitted_result$x,
    fitted_result$mean,
    col = "red",
    lwd = 2
  )
  # # weighted average line
  # abline(h = y_wmean, col = "blue",  lty = 2)
  # weighted linear fit
  abline(lin_fit,     col = "green", lty = 2, lwd = 1)
  # weighted quadratic curve
  lines(x_grid, quad_pred, col = "purple", lty = 2, lwd = 1)
  # lfdr after
  lfdr_after  <- fash_fit1_update$lfdr[selected_index]
  # lfdr before
  lfdr_before <- fash_fit1$lfdr[selected_index]
  # caption text
  caption <- sprintf("lfdr (raw) = %.3f, lfdr (adj) = %.3f",
                     lfdr_before, lfdr_after)
  title(sub = caption, cex.sub = 0.8)
}

Past versions of unnamed-chunk-21-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12
d73f3f1	Ziang Zhang	2025-11-09

par(mfrow = c(1,1))

Another highlighted pair in the original analysis is ‘ENSG00000166704_rs8107849’:

selected_index <- which("ENSG00000166704_rs8107849" == names(datasets))
# shorthand 
x  <- datasets[[selected_index]]$x
y  <- datasets[[selected_index]]$y
se <- datasets[[selected_index]]$SE
w  <- 1 / (se^2)
y_min <- min(y - 2 * se)
y_max <- max(y + 2 * se)
# weighted mean
y_wmean <- sum(y * w) / sum(w)
# weighted linear fit
lin_fit <- lm(y ~ x, weights = w)
# weighted quadratic fit
quad_fit  <- lm(y ~ poly(x, 2, raw = TRUE), weights = w)
x_grid    <- seq(min(x), max(x), length.out = 200)
quad_pred <- predict(quad_fit, newdata = data.frame(x = x_grid))
# FASH fit (after adjustment)
fitted_result <- predict(
  fash_fit1_update,
  index      = selected_index,
  smooth_var = seq(0, 15, by = 0.1)
)
# FASH fit (before adjustment)
fitted_result_before <- predict(
  fash_fit1,
  index      = selected_index,
  smooth_var = seq(0, 15, by = 0.1)
)
par(mfrow = c(1,1))
plot(
  x, y,
  pch  = 20,
  col  = "black",
  xlab = "Time",
  ylab = "Effect Est",
  # main = names(datasets)[selected_index],
  ylim = c(y_min, y_max)
)
variant_id <- strsplit(names(datasets)[selected_index], "_")[[1]][2]
gene_symbol <- full_map$hgnc_symbol[full_map$ensembl_gene_id == "ENSG00000166704"]
title(main = paste0(gene_symbol, ": ", variant_id))
arrows(
  x0 = x,
  y0 = y - 2 * se,
  x1 = x,
  y1 = y + 2 * se,
  length = 0.05,
  angle  = 90,
  code   = 3,
  col    = "black"
)
polygon(
  c(fitted_result_before$x, rev(fitted_result_before$x)),
  c(fitted_result_before$lower, rev(fitted_result_before$upper)),
  col    = rgb(1, 0, 0, 0.3),
  border = NA
)
# posterior mean curve
lines(
  fitted_result_before$x,
  fitted_result_before$mean,
  col = "red",
  lwd = 2
)
# # weighted average line
# abline(h = y_wmean, col = "blue",  lty = 2)
# weighted linear fit
abline(lin_fit, col = "green", lty = 2, lwd = 1)
# weighted quadratic curve
lines(x_grid, quad_pred, col = "purple", lty = 2, lwd = 1)
# lfdr before
lfdr_before <- fash_fit1$lfdr[selected_index]
# caption text
caption <- sprintf("lfdr (raw) = %.3f",
                   lfdr_before)
title(sub = caption, cex.sub = 0.8)

Past versions of unnamed-chunk-22-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12
d73f3f1	Ziang Zhang	2025-11-09

plot(
  x, y,
  pch  = 20,
  col  = "black",
  xlab = "Time",
  ylab = "Effect Est",
  # main = names(datasets)[selected_index],
  ylim = c(y_min, y_max)
)
title(main = paste0(gene_symbol, ": ", variant_id))
arrows(
  x0 = x,
  y0 = y - 2 * se,
  x1 = x,
  y1 = y + 2 * se,
  length = 0.05,
  angle  = 90,
  code   = 3,
  col    = "black"
)
polygon(
  c(fitted_result$x, rev(fitted_result$x)),
  c(fitted_result$lower, rev(fitted_result$upper)),
  col    = rgb(1, 0, 0, 0.3),
  border = NA
)
# posterior mean curve
lines(
  fitted_result$x,
  fitted_result$mean,
  col = "red",
  lwd = 2
)
# # weighted average line
# abline(h = y_wmean, col = "blue",  lty = 2)
# weighted linear fit
abline(lin_fit, col = "green", lty = 2, lwd = 1)
# weighted quadratic curve
lines(x_grid, quad_pred, col = "purple", lty = 2, lwd = 1)
# lfdr after
lfdr_after  <- fash_fit1_update$lfdr[selected_index]
# caption text
caption <- sprintf("lfdr (adj) = %.3f",
                   lfdr_after)
title(sub = caption, cex.sub = 0.8)

Past versions of unnamed-chunk-22-2.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

par(mfrow = c(1,1))

This pair is not significant in FASH with or without BF adjustment.

Take a look at the most significant variants for the gene ‘ENSG00000166704’:

# get the indices of the highlighted pairs for ENSG00000166704
ZNF606_pairs <- names(datasets)[grep("ENSG00000166704", names(datasets))]
# pick the most significant four variants
all_selected_indices <- grep("ENSG00000166704", names(datasets))
lfdr_values <- fash_fit1_update$lfdr[all_selected_indices]
selected_indices <- all_selected_indices[order(lfdr_values)][1:4]
# plot
par(mfrow = c(2,2))
for (selected_index in selected_indices) {
  # shorthand 
  x  <- datasets[[selected_index]]$x
  y  <- datasets[[selected_index]]$y
  se <- datasets[[selected_index]]$SE
  w  <- 1 / (se^2)
  y_min <- min(y - 2 * se)
  y_max <- max(y + 2 * se)
  # weighted mean
  y_wmean <- sum(y * w) / sum(w)
  # weighted linear fit
  lin_fit <- lm(y ~ x, weights = w)
  # weighted quadratic fit
  quad_fit  <- lm(y ~ poly(x, 2, raw = TRUE), weights = w)
  x_grid    <- seq(min(x), max(x), length.out = 200)
  quad_pred <- predict(quad_fit, newdata = data.frame(x = x_grid))
  # FASH fit (after adjustment)
  fitted_result <- predict(
    fash_fit1_update,
    index      = selected_index,
    smooth_var = seq(0, 15, by = 0.1)
  )
  plot(
    x, y,
    pch  = 20,
    col  = "black",
    xlab = "Time",
    ylab = "Effect Est",
    # main = names(datasets)[selected_index],
    ylim = c(y_min, y_max)
  )
  variant_id <- strsplit(names(datasets)[selected_index], "_")[[1]][2]
  gene_symbol <- full_map$hgnc_symbol[full_map$ensembl_gene_id == "ENSG00000166704"]
  title(main = paste0(gene_symbol, ": ", variant_id))
  arrows(
    x0 = x,
    y0 = y - 2 * se,
    x1 = x,
    y1 = y + 2 * se,
    length = 0.05,
    angle  = 90,
    code   = 3,
    col    = "black"
  )
  polygon(
    c(fitted_result$x, rev(fitted_result$x)),
    c(fitted_result$lower, rev(fitted_result$upper)),
    col    = rgb(1, 0, 0, 0.3),
    border = NA
  )
  # posterior mean curve
  lines(
    fitted_result$x,
    fitted_result$mean,
    col = "red",
    lwd = 2
  )
  # # weighted average line
  # abline(h = y_wmean, col = "blue",  lty = 2)
  # weighted linear fit
  abline(lin_fit,     col = "green", lty = 2, lwd = 1)
  # weighted quadratic curve
  lines(x_grid, quad_pred, col = "purple", lty = 2, lwd = 1)
  # lfdr after
  lfdr_after  <- fash_fit1_update$lfdr[selected_index]
  # lfdr before
  lfdr_before <- fash_fit1$lfdr[selected_index]
  # caption text
  caption <- sprintf("lfdr (raw) = %.3f, lfdr (adj) = %.3f",
                     lfdr_before, lfdr_after)
  title(sub = caption, cex.sub = 0.8)
}

Past versions of unnamed-chunk-23-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12
d73f3f1	Ziang Zhang	2025-11-09

par(mfrow = c(1,1))

It seems like the BF adjustment significantly increased the lfdr for all these variants, and strongly penalized the curves toward the constant function.

Another two highlighted genes are ‘ENSG00000115641’ and ‘ENSG00000167173’:

# pick the most significant variant for each gene
all_fhl2_indices <- fash_highlighted1[grep("ENSG00000115641", names(datasets)[fash_highlighted1])]
lfdr_values_fhl2 <- fash_fit1_update$lfdr[all_fhl2_indices]
selected_fhl2_index <- all_fhl2_indices[which.min(lfdr_values_fhl2)]
all_c15orf39_indices <- grep("ENSG00000167173", names(datasets))
lfdr_values_c15orf39 <- fash_fit1_update$lfdr[all_c15orf39_indices]
selected_c15orf39_index <- all_c15orf39_indices[which.min(lfdr_values_c15orf39)]
# plot
par(mfrow = c(1,1))
for (selected_index in c(selected_fhl2_index, selected_c15orf39_index)) {
  # shorthand 
  x  <- datasets[[selected_index]]$x
  y  <- datasets[[selected_index]]$y
  se <- datasets[[selected_index]]$SE
  w  <- 1 / (se^2)
  y_min <- min(y - 2 * se)
  y_max <- max(y + 2 * se)
  # weighted mean
  y_wmean <- sum(y * w) / sum(w)
  # weighted linear fit
  lin_fit <- lm(y ~ x, weights = w)
  # weighted quadratic fit
  quad_fit  <- lm(y ~ poly(x, 2, raw = TRUE), weights = w)
  x_grid    <- seq(min(x), max(x), length.out = 200)
  quad_pred <- predict(quad_fit, newdata = data.frame(x = x_grid))
  # FASH fit (after adjustment)
  fitted_result <- predict(
    fash_fit1_update,
    index      = selected_index,
    smooth_var = seq(0, 15, by = 0.1)
  )
  plot(
    x, y,
    pch  = 20,
    col  = "black",
    xlab = "Time",
    ylab = "Effect Est",
    # main = names(datasets)[selected_index],
    ylim = c(y_min, y_max)
  )
  variant_id <- strsplit(names(datasets)[selected_index], "_")[[1]][2]
  gene_symbol <- full_map$hgnc_symbol[full_map$ensembl_gene_id == strsplit(names(datasets)[selected_index], "_")[[1]][1]]
  title(main = paste0(gene_symbol, ": ", variant_id))
  arrows(
    x0 = x,
    y0 = y - 2 * se,
    x1 = x,
    y1 = y + 2 * se,
    length = 0.05,
    angle  = 90,
    code   = 3,
    col    = "black"
  )
  polygon(
    c(fitted_result$x, rev(fitted_result$x)),
    c(fitted_result$lower, rev(fitted_result$upper)),
    col    = rgb(1, 0, 0, 0.3),
    border = NA
  )
  # posterior mean curve
  lines(
    fitted_result$x,
    fitted_result$mean,
    col = "red",
    lwd = 2
  )
  # # weighted average line
  # abline(h = y_wmean, col = "blue",  lty = 2)
  # weighted linear fit
  abline(lin_fit,     col = "green", lty = 2, lwd = 1)
  # weighted quadratic curve
  lines(x_grid, quad_pred, col = "purple", lty = 2, lwd = 1)
  # lfdr after
  lfdr_after  <- fash_fit1_update$lfdr[selected_index]
  # lfdr before
  lfdr_before <- fash_fit1$lfdr[selected_index]
  # caption text
  caption <- sprintf("lfdr (raw) = %.3f, lfdr (adj) = %.3f",
                     lfdr_before, lfdr_after)
  title(sub = caption, cex.sub = 0.8)
}

Past versions of unnamed-chunk-24-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

Past versions of unnamed-chunk-24-2.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

par(mfrow = c(1,1))

There is a significant variant for ENSG00000115641, but not for ENSG00000167173 after BF adjustment.

Some examples of null pairs:

genes_not_highlighted1 <- setdiff(all_genes, genes_highlighted1)
pairs_not_highlighted1 <- setdiff(names(datasets), pairs_highlighted1)
par(mfrow = c(2,2))
for (i in 1:4) {
  selected_gene <- genes_not_highlighted1[i]
  pairs_of_selected_gene <- grep(selected_gene, pairs_not_highlighted1, value = TRUE)
  selected_indices <- which(names(datasets) %in% pairs_of_selected_gene)

  # here we pick the *least* interesting one: max lfdr after adjustment
  selected_index <- selected_indices[
    which(fash_fit1_update$lfdr[selected_indices] ==
            max(fash_fit1_update$lfdr[selected_indices]))[1]
  ]

  # shorthand
  x  <- datasets[[selected_index]]$x
  y  <- datasets[[selected_index]]$y
  se <- datasets[[selected_index]]$SE
  w  <- 1 / (se^2)

  y_min <- min(y - 2 * se)
  y_max <- max(y + 2 * se)

  # weighted mean
  y_wmean <- sum(y * w) / sum(w)

  # weighted linear fit
  lin_fit <- lm(y ~ x, weights = w)

  # weighted quadratic fit
  quad_fit  <- lm(y ~ poly(x, 2, raw = TRUE), weights = w)
  x_grid    <- seq(min(x), max(x), length.out = 200)
  quad_pred <- predict(quad_fit, newdata = data.frame(x = x_grid))

  # FASH fit (after adjustment)
  fitted_result <- predict(
    fash_fit1_update,
    index      = selected_index,
    smooth_var = seq(0, 15, by = 0.1)
  )

  # lfdr before and after
  lfdr_before <- fash_fit1$lfdr[selected_index]
  lfdr_after  <- fash_fit1_update$lfdr[selected_index]

  # caption text
  caption <- sprintf("lfdr (raw) = %.3f, lfdr (adj) = %.3f",
                     lfdr_before, lfdr_after)

  plot(
    x, y,
    pch  = 20,
    col  = "black",
    xlab = "Time",
    ylab = "Effect Est",
    # main = names(datasets)[selected_index],
    ylim = c(y_min, y_max)
  )
  
  variant_id <- strsplit(names(datasets)[selected_index], "_")[[1]][2]
  gene_symbol <- full_map$hgnc_symbol[full_map$ensembl_gene_id == selected_gene]
  title(main = paste0(gene_symbol, ": ", variant_id))

  arrows(
    x0 = x,
    y0 = y - 2 * se,
    x1 = x,
    y1 = y + 2 * se,
    length = 0.05,
    angle  = 90,
    code   = 3,
    col    = "black"
  )

  polygon(
    c(fitted_result$x, rev(fitted_result$x)),
    c(fitted_result$lower, rev(fitted_result$upper)),
    col    = rgb(1, 0, 0, 0.3),
    border = NA
  )

  # posterior mean curve
  lines(
    fitted_result$x,
    fitted_result$mean,
    col = "red",
    lwd = 2
  )

  # # weighted average line (replaces simple mean)
  # abline(h = y_wmean, col = "blue",  lty = 2)

  # weighted linear fit
  abline(lin_fit,     col = "green", lty = 2, lwd = 1)

  # weighted quadratic curve
  lines(x_grid, quad_pred, col = "purple", lty = 2, lwd = 1)

  # add caption as subtitle
  title(sub = caption, cex.sub = 0.8)
}

Past versions of unnamed-chunk-25-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

par(mfrow = c(1,1))

Comparing with Strober et.al

We will compare the detected dynamic eQTLs with the results from Strober et.al.

── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──
✔ dplyr     1.1.4     ✔ readr     2.1.5
✔ forcats   1.0.1     ✔ stringr   1.5.2
✔ ggplot2   4.0.0     ✔ tibble    3.3.0
✔ lubridate 1.9.4     ✔ tidyr     1.3.1
✔ purrr     1.1.0     
── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
✖ dplyr::filter() masks stats::filter()
✖ dplyr::lag()    masks stats::lag()
✖ dplyr::select() masks biomaRt::select()
✖ tidyr::unite()  masks ggVennDiagram::unite()
ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors

Let’s take a look at the overlap between the two methods used in Strober et.al and FASH (order 1):

gene_sets <- list(
  "Strober (Nonlinear)" = genes_highlighted_strober_nonlinear,
  "Strober (Linear)" = genes_highlighted_strober_linear,
  "FASH (1)" = genes_highlighted1
)
ggVennDiagram(gene_sets, label = "both") +
  scale_fill_gradient(low="grey90",high = "red") +
  theme(legend.position = "right")  # Move legend to the right

Past versions of unnamed-chunk-27-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

Produce another Venn diagram for the pairs detected by the three methods:

pair_sets <- list(
  "Strober (Nonlinear)" = pairs_highlighted_strober_nonlinear,
  "Strober (Linear)" = pairs_highlighted_strober_linear,
  "FASH (1)" = pairs_highlighted1
)
ggVennDiagram(pair_sets, label = "both") +
  scale_fill_gradient(low="grey90",high = "red") +
  theme(legend.position = "right")  # Move legend to the right

Past versions of unnamed-chunk-28-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

Produce similar Venn diagrams for genes and pairs detected by FASH without BF adjustment:

gene_sets_unadj <- list(
  "Strober (Nonlinear)" = genes_highlighted_strober_nonlinear,
  "Strober (Linear)" = genes_highlighted_strober_linear,
  "FASH (1) unadj" = genes_highlighted1_before
)
ggVennDiagram(gene_sets_unadj, label = "both") +
  scale_fill_gradient(low="grey90",high = "red") +
  theme(legend.position = "right")  # Move legend to the right

Past versions of unnamed-chunk-29-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12
d73f3f1	Ziang Zhang	2025-11-09

pair_sets_unadj <- list(
  "Strober (Nonlinear)" = pairs_highlighted_strober_nonlinear,
  "Strober (Linear)" = pairs_highlighted_strober_linear,
  "FASH (1) unadj" = pairs_highlighted1_before
)
ggVennDiagram(pair_sets_unadj, label = "both") +
  scale_fill_gradient(low="grey90",high = "red") +
  theme(legend.position = "right")  # Move legend to the right

Past versions of unnamed-chunk-29-2.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

There is a large number of genes only detected by FASH (order 1). Let’s take a look at the 4 pairs that are least significant from FASH:

Past versions of unnamed-chunk-30-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

Let’s also take a look at the 4 pairs that are most significant from FASH:

Past versions of unnamed-chunk-31-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

Let’s also look at the genes that were missed by FASH, but detected by Strober et.al. In this case, we will pick the most significant pair for each gene in FASH:

Past versions of unnamed-chunk-32-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12
d73f3f1	Ziang Zhang	2025-11-09

Take a look at the same plot but with the unadjusted FASH results:

## produce four plots for four genes
par(mfrow = c(2,2))
for (i in 1:4) {
  selected_gene <- gene_missed[i]
  pairs_of_selected_gene <- grep(selected_gene, names(datasets), value = TRUE)
  selected_indices <- which(names(datasets) %in% pairs_of_selected_gene)

  # pick the pair with smallest adjusted lfdr
  selected_index <- selected_indices[
    which(fash_fit1_update$lfdr[selected_indices] ==
            min(fash_fit1_update$lfdr[selected_indices]))[1]
  ]

  # shorthand
  x  <- datasets[[selected_index]]$x
  y  <- datasets[[selected_index]]$y
  se <- datasets[[selected_index]]$SE
  w  <- 1 / (se^2)

  y_min <- min(y - 2 * se)
  y_max <- max(y + 2 * se)

  # weighted mean
  y_wmean <- sum(y * w) / sum(w)

  # weighted linear fit
  lin_fit <- lm(y ~ x, weights = w)

  # weighted quadratic fit
  quad_fit  <- lm(y ~ poly(x, 2, raw = TRUE), weights = w)
  x_grid    <- seq(min(x), max(x), length.out = 200)
  quad_pred <- predict(quad_fit, newdata = data.frame(x = x_grid))

  # FASH fit (before adjustment)
  fitted_result <- predict(
    fash_fit1,
    index      = selected_index,
    smooth_var = seq(0, 15, by = 0.1)
  )

  # lfdr before and after
  lfdr_before <- fash_fit1$lfdr[selected_index]
  lfdr_after  <- fash_fit1_update$lfdr[selected_index]

  # caption text
  caption <- sprintf("lfdr (raw) = %.3f, lfdr (adj) = %.3f",
                     lfdr_before, lfdr_after)

  plot(
    x, y,
    pch  = 20,
    col  = "black",
    xlab = "Time",
    ylab = "Effect Est",
    # main = names(datasets)[selected_index],
    ylim = c(y_min, y_max)
  )
  
  variant_id <- strsplit(names(datasets)[selected_index], "_")[[1]][2]
  title(main = paste0(gene_missed_gene_symbol[i], ": ", variant_id))

  arrows(
    x0 = x,
    y0 = y - 2 * se,
    x1 = x,
    y1 = y + 2 * se,
    length = 0.05,
    angle  = 90,
    code   = 3,
    col    = "black"
  )

  polygon(
    c(fitted_result$x, rev(fitted_result$x)),
    c(fitted_result$lower, rev(fitted_result$upper)),
    col    = rgb(1, 0, 0, 0.3),
    border = NA
  )

  # posterior mean curve
  lines(
    fitted_result$x,
    fitted_result$mean,
    col = "red",
    lwd = 2
  )

  # # weighted average line (replaces inv_weights version)
  # abline(h = y_wmean, col = "blue",  lty = 2)

  # weighted linear fit
  abline(lin_fit,     col = "green", lty = 2, lwd = 1)

  # weighted quadratic curve
  lines(x_grid, quad_pred, col = "purple", lty = 2, lwd = 1)

  # add caption as subtitle
  title(sub = caption, cex.sub = 0.8)
}

Past versions of unnamed-chunk-33-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

par(mfrow = c(1,1))

Classifying dynamic eQTLs

Following the definition in Strober et.al, we will classify the detected dynamic eQTLs into different categories:

• Early: eQTLs with strongest effect during the first three days: \(\max_{t\leq3} |\beta(t)| - \max_{t> 3} |\beta(t)| > 0\).

• Late: eQTLs with strongest effect during the last four days: \(\max_{t\geq 12} |\beta(t)| - \max_{t< 12} |\beta(t)| > 0\).

• Middle: eQTLs with strongest effect during days 4-11: \(\max_{4\leq t\leq 11} |\beta(t)| - \max_{t> 11 | t< 4} |\beta(t)| > 0\).

• Switch: eQTLs with effect sign switch during the time course such that \(\min\{\max\beta(t)^+,\max\beta(t)^-\}-c>0\) where \(c\) is a threshold that we set to 0.25 (which means with two alleles, the maximal difference of effect size is at least \(\geq 2\times\min\{\max\beta(t)^+,\max\beta(t)^-\}\times2 \geq 2 \times 0.25 \times 2 = 1\)).

We will take a look at the significant pairs detected by FASH (order 1), and classify them based on the false sign rate (lfsr).

Early dynamic eQTLs

smooth_var_refined = seq(0,15, by = 0.1)
functional_early <- function(x){
  max(abs(x[smooth_var_refined <= 3])) - max(abs(x[smooth_var_refined > 3]))
}
testing_early_dyn <- testing_functional(functional_early,
                                              lfsr_cal = function(x){mean(x <= 0)},
                                              fash = fash_fit1,
                                              indices = fash_highlighted1,
                                              smooth_var = smooth_var_refined)

How many pairs and how many unique genes are classified as early dynamic eQTLs?

load(paste0(result_dir, "/classify_dyn_eQTLs_early.RData"))
early_indices <- testing_early_dyn$indices[testing_early_dyn$cfsr <= alpha]
length(early_indices)

[1] 129

early_genes <- unique(sapply(strsplit(names(datasets)[early_indices], "_"), "[[", 1))
length(early_genes)

[1] 18

Let’s take a look at the top-ranked early dynamic eQTLs:

Past versions of unnamed-chunk-36-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

It is evident that these variants have largest \(|\beta(t)|\) during the first three days.

Middle dynamic eQTLs

functional_middle <- function(x){
  max(abs(x[smooth_var_refined <= 11 & smooth_var_refined >= 4])) - max(abs(x[smooth_var_refined > 11]), abs(x[smooth_var_refined < 4]))
}
testing_middle_dyn <- testing_functional(functional_middle, 
                                               lfsr_cal = function(x){mean(x <= 0)},
                                               fash = fash_fit1, 
                                               indices = fash_highlighted1, 
                                               num_cores = num_cores,
                                               smooth_var = smooth_var_refined)

How many pairs and how many unique genes are classified as middle dynamic eQTLs?

load(paste0(result_dir, "/classify_dyn_eQTLs_middle.RData"))
middle_indices <- testing_middle_dyn$indices[testing_middle_dyn$cfsr <= alpha]
length(middle_indices)

[1] 54

middle_genes <- unique(sapply(strsplit(names(datasets)[middle_indices], "_"), "[[", 1))
length(middle_genes)

[1] 17

map <- getBM(
  attributes = c("ensembl_gene_id", "hgnc_symbol"),
  filters    = "ensembl_gene_id",
  values     = middle_genes,
  mart       = mart
)

middle_genes_symbols <- map$hgnc_symbol[match(middle_genes, map$ensembl_gene_id)]

Take a look at their results:

par(mfrow = c(2,2))
for (i in 1:4) {
  selected_index <- sample(middle_indices, 1)
  fitted_result <- predict(fash_fit1_update,
                           index = selected_index,
                           smooth_var = seq(0, 15, by = 0.1))
  plot(
    datasets[[selected_index]]$x,
    datasets[[selected_index]]$y,
    pch = 20,
    col = "black",
    xlab = "Time",
    ylab = "Effect Est",
    # main = paste0(names(datasets)[selected_index]),
    ylim = c(
      min(datasets[[selected_index]]$y - 2 * datasets[[selected_index]]$SE),
      max(datasets[[selected_index]]$y + 2 * datasets[[selected_index]]$SE)
    )
  )
  variant_id <- strsplit(names(datasets)[selected_index], "_")[[1]][2]
  gene_symbol <- middle_genes_symbols[match(strsplit(names(datasets)[selected_index], "_")[[1]][1], middle_genes)]
  title(main = paste0(gene_symbol, ": ", variant_id))
  arrows(
    datasets[[selected_index]]$x,
    datasets[[selected_index]]$y - 2 * datasets[[selected_index]]$SE,
    datasets[[selected_index]]$x,
    datasets[[selected_index]]$y + 2 * datasets[[selected_index]]$SE,
    length = 0.05,
    angle = 90,
    code = 3,
    col = "black"
  )
  lines(fitted_result$x,
        fitted_result$mean,
        col = "red",
        lwd = 2)
  abline(h = 0, col = "blue", lty = 2)
  polygon(
    c(fitted_result$x, rev(fitted_result$x)),
    c(fitted_result$lower, rev(fitted_result$upper)),
    col = rgb(1, 0, 0, 0.3),
    border = NA
  )
  
  # add lfsr
  lfsr_adj <- testing_middle_dyn$lfsr[testing_middle_dyn$indices == selected_index]
  
  caption <- sprintf("lfsr (adj) = %.3f",
                     lfsr_adj)

  title(sub = caption, cex.sub = 0.8)
}

Past versions of unnamed-chunk-39-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

par(mfrow = c(1,1))

Late dynamic eQTLs

functional_late <- function(x){
  max(abs(x[smooth_var_refined >= 12])) - max(abs(x[smooth_var_refined < 12]))
}
testing_late_dyn <- testing_functional(functional_late, 
                                             lfsr_cal = function(x){mean(x <= 0)},
                                             fash = fash_fit1, 
                                             indices = fash_highlighted1, 
                                             num_cores = num_cores,
                                             smooth_var = smooth_var_refined)

How many pairs and how many unique genes are classified as late dynamic eQTLs?

load(paste0(result_dir, "/classify_dyn_eQTLs_late.RData"))
late_indices <- testing_late_dyn$indices[testing_late_dyn$cfsr <= alpha]
length(late_indices)

[1] 50

late_genes <- unique(sapply(strsplit(names(datasets)[late_indices], "_"), "[[", 1))
length(late_genes)

[1] 18

map <- getBM(
  attributes = c("ensembl_gene_id", "hgnc_symbol"),
  filters    = "ensembl_gene_id",
  values     = late_genes,
  mart       = mart
)
late_genes_symbols <- map$hgnc_symbol[match(late_genes, map$ensembl_gene_id)]
late_genes_symbols[6] <- "SCO2"

Let’s take a look at the top-ranked late dynamic eQTLs:

Past versions of unnamed-chunk-42-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

Switch dynamic eQTLs

How many pairs and how many unique genes are classified as switch dynamic eQTLs?

switch_threshold <- 0.25
functional_switch <- function(x){
  # compute the radius of x, measured by deviation from 0 from below and from above
  x_pos <- x[x > 0]
  x_neg <- x[x < 0]
  if(length(x_pos) == 0 || length(x_neg) == 0){
    return(0)
  }
  min(max(abs(x_pos)), max(abs(x_neg))) - switch_threshold
}
testing_switch_dyn <- testing_functional(functional_switch, 
                                               lfsr_cal = function(x){mean(x <= 0)},
                                               fash = fash_fit1, 
                                               indices = fash_highlighted1, 
                                               num_cores = num_cores,
                                               smooth_var = smooth_var_refined)

load(paste0(result_dir, "/classify_dyn_eQTLs_switch.RData"))
switch_indices <- testing_switch_dyn$indices[testing_switch_dyn$cfsr <= alpha]
length(switch_indices)

[1] 1284

switch_genes <- unique(sapply(strsplit(names(datasets)[switch_indices], "_"), "[[", 1))
length(switch_genes)

[1] 285

map <- getBM(
  attributes = c("ensembl_gene_id", "hgnc_symbol"),
  filters    = "ensembl_gene_id",
  values     = switch_genes,
  mart       = mart
)
switch_genes_symbols <- map$hgnc_symbol[match(switch_genes, map$ensembl_gene_id)]
selected_switch_genes_symbols <- c("SCN5A", "USP3", "VAMP8", "CCND1")
selected_switch_genes <- map$ensembl_gene_id[match(selected_switch_genes_symbols, map$hgnc_symbol)]

Let’s take a look at the top-ranked switch dynamic eQTLs:

Past versions of unnamed-chunk-45-1.png

Version	Author	Date
83145cc	Ziang Zhang	2025-12-12

Gene Set Enrichment Analysis

library(clusterProfiler)
library(tidyverse)
library(msigdbr)
library(org.Hs.eg.db)
library(cowplot)

## Retrieve Hallmark gene sets for Homo sapiens (use Ensembl IDs)
m_t2g <- msigdbr(species = "Homo sapiens", category = "H") %>% 
  mutate(ensembl_use = dplyr::coalesce(ensembl_gene, db_ensembl_gene)) %>% 
  dplyr::filter(!is.na(ensembl_use)) %>% 
  dplyr::select(gs_name, ensembl_use) %>%
  dplyr::distinct()    # one row per (pathway, Ensembl) pair


## A function to check gene-enrichment using Ensembl IDs,
## forcing the universe to be exactly background_gene
enrich_set <- function(genes_selected,
                       background_gene,
                       q_val_cutoff = 0.05,
                       pvalueCutoff = 0.05) {

  # ensure character vectors & unique
  genes_selected_raw  <- unique(as.character(genes_selected))
  background_gene_raw <- unique(as.character(background_gene))

  # we'll enforce that the test universe is exactly these:
  universe_for_test <- background_gene_raw

  # genes that are in Hallmark already
  hallmark_genes <- unique(m_t2g$ensembl_use)

  # background genes that are NOT in Hallmark (no annotation)
  bg_not_in_hallmark <- setdiff(universe_for_test, hallmark_genes)

  # extend TERM2GENE so that *all* background genes appear in it at least once
  # add them to a dummy pathway that we will later drop
  dummy_id <- "__DUMMY_BACKGROUND__"

  if (length(bg_not_in_hallmark) > 0) {
    dummy_t2g <- tibble(
      gs_name     = dummy_id,
      ensembl_use = bg_not_in_hallmark
    )
    TERM2GENE_full <- bind_rows(m_t2g, dummy_t2g)
  } else {
    TERM2GENE_full <- m_t2g
  }

  # also make sure selected genes are a subset of the universe
  genes_sel_used <- intersect(genes_selected_raw, universe_for_test)

  # message("Original selected genes: ", length(genes_selected_raw),
  #         " ; used in enrichment: ", length(genes_sel_used))
  # message("Universe size (background_gene): ", length(universe_for_test))

  enrich_res <- enricher(
    gene          = genes_sel_used,
    TERM2GENE     = TERM2GENE_full,
    universe      = universe_for_test,
    pAdjustMethod = "BH",
    qvalueCutoff  = q_val_cutoff,
    pvalueCutoff  = pvalueCutoff
  )

  if (is.null(enrich_res) || nrow(enrich_res@result) == 0L) {
    return(enrich_res)
  }

  df <- enrich_res@result

  # drop the dummy term from results
  df <- df %>% dplyr::filter(ID != dummy_id)

  # keep original ratios for reference
  df$GeneRatio_orig <- df$GeneRatio
  df$BgRatio_orig   <- df$BgRatio

  # now recompute ratios using exactly:
  #   - denominator for GeneRatio = number of selected genes in universe
  #   - denominator for BgRatio   = number of background genes
  n_sel_total <- length(genes_sel_used)
  n_bg_total  <- length(universe_for_test)

  df$GeneRatio_fixed <- paste0(df$Count,   "/", n_sel_total)
  df$BgRatio_fixed   <- paste0(df$setSize, "/", n_bg_total)

  enrich_res@result <- df
  enrich_res
}

Among all the genes highlighted by FASH:

result <- enrich_set(genes_selected = genes_highlighted1, background_gene = all_genes)
result@result %>% 
  filter(pvalue < 0.05) %>%
  dplyr::select(GeneRatio, BgRatio, pvalue, qvalue)

                           GeneRatio BgRatio     pvalue   qvalue
HALLMARK_HYPOXIA             26/1295 89/6362 0.02879958 0.382977
HALLMARK_COAGULATION         11/1295 31/6362 0.03642565 0.382977
HALLMARK_MYOGENESIS          20/1295 67/6362 0.04127072 0.382977
HALLMARK_KRAS_SIGNALING_UP   15/1295 47/6362 0.04152590 0.382977
HALLMARK_KRAS_SIGNALING_DN   10/1295 28/6362 0.04318383 0.382977

Among the genes highlighted by FASH that are classified as early dynamic eQTLs:

result <- enrich_set(genes_selected = early_genes, background_gene = all_genes)
result@result %>% 
  filter(pvalue < 0.05) %>%
  dplyr::select(GeneRatio, BgRatio, pvalue, qvalue)

                     GeneRatio BgRatio     pvalue     qvalue
HALLMARK_P53_PATHWAY      2/18 83/6362 0.02247213 0.09461948

Among the genes highlighted by FASH that are classified as middle dynamic eQTLs:

result <- enrich_set(genes_selected = middle_genes, background_gene = all_genes)
result@result %>% 
  filter(pvalue < 0.05) %>%
  dplyr::select(GeneRatio, BgRatio, pvalue, qvalue)

                    GeneRatio BgRatio      pvalue     qvalue
HALLMARK_COMPLEMENT      2/17 57/6362 0.009839637 0.09321762

Among the genes highlighted by FASH that are classified as late dynamic eQTLs:

result <- enrich_set(genes_selected = late_genes, background_gene = all_genes)
result@result %>% 
  filter(pvalue < 0.05) %>%
  dplyr::select(GeneRatio, BgRatio, pvalue, qvalue)

                                   GeneRatio  BgRatio      pvalue      qvalue
HALLMARK_ANDROGEN_RESPONSE              3/18  57/6362 0.000505832 0.003727183
HALLMARK_OXIDATIVE_PHOSPHORYLATION      2/18 119/6362 0.043671354 0.160894461

Among the genes highlighted by FASH that are classified as switch dynamic eQTLs:

result <- enrich_set(genes_selected = switch_genes, background_gene = all_genes)
result@result %>% 
  filter(pvalue < 0.05) %>%
  dplyr::select(GeneRatio, BgRatio, pvalue, qvalue)

                                   GeneRatio BgRatio      pvalue     qvalue
HALLMARK_HYPOXIA                      11/285 89/6362 0.001944003 0.04034811
HALLMARK_MYOGENESIS                    9/285 67/6362 0.002780865 0.04034811
HALLMARK_P53_PATHWAY                  10/285 83/6362 0.003726032 0.04034811
HALLMARK_XENOBIOTIC_METABOLISM         9/285 71/6362 0.004143860 0.04034811
HALLMARK_PI3K_AKT_MTOR_SIGNALING       7/285 55/6362 0.010785281 0.07937656
HALLMARK_APOPTOSIS                     8/285 70/6362 0.012426809 0.07937656
HALLMARK_TNFA_SIGNALING_VIA_NFKB       7/285 58/6362 0.014266327 0.07937656
HALLMARK_HEDGEHOG_SIGNALING            3/285 15/6362 0.027120719 0.11736452
HALLMARK_NOTCH_SIGNALING               3/285 15/6362 0.027120719 0.11736452
HALLMARK_INTERFERON_GAMMA_RESPONSE     6/285 56/6362 0.038073617 0.14828672
HALLMARK_IL2_STAT5_SIGNALING           7/285 75/6362 0.049784481 0.17627041

Session information

sessionInfo()

R version 4.5.1 (2025-06-13)
Platform: aarch64-apple-darwin20
Running under: macOS Sequoia 15.6.1

Matrix products: default
BLAS:   /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/lib/libRblas.0.dylib 
LAPACK: /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/lib/libRlapack.dylib;  LAPACK version 3.12.1

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

time zone: America/Chicago
tzcode source: internal

attached base packages:
[1] stats4    stats     graphics  grDevices utils     datasets  methods  
[8] base     

other attached packages:
 [1] cowplot_1.2.0          org.Hs.eg.db_3.21.0    AnnotationDbi_1.70.0  
 [4] IRanges_2.42.0         S4Vectors_0.46.0       Biobase_2.68.0        
 [7] BiocGenerics_0.54.1    generics_0.1.4         msigdbr_25.1.1        
[10] clusterProfiler_4.16.0 lubridate_1.9.4        forcats_1.0.1         
[13] stringr_1.5.2          dplyr_1.1.4            purrr_1.1.0           
[16] readr_2.1.5            tidyr_1.3.1            tibble_3.3.0          
[19] ggplot2_4.0.0          tidyverse_2.0.0        ggVennDiagram_1.5.4   
[22] biomaRt_2.64.0         fashr_0.1.42           workflowr_1.7.2       

loaded via a namespace (and not attached):
  [1] RColorBrewer_1.1-3      rstudioapi_0.17.1       jsonlite_2.0.0         
  [4] magrittr_2.0.4          ggtangle_0.0.8          farver_2.1.2           
  [7] rmarkdown_2.30          fs_1.6.6                vctrs_0.6.5            
 [10] memoise_2.0.1           ggtree_3.16.3           mixsqp_0.3-54          
 [13] htmltools_0.5.8.1       progress_1.2.3          curl_7.0.0             
 [16] gridGraphics_0.5-1      sass_0.4.10             bslib_0.9.0            
 [19] plyr_1.8.9              httr2_1.2.1             cachem_1.1.0           
 [22] TMB_1.9.18              igraph_2.2.0            whisker_0.4.1          
 [25] lifecycle_1.0.4         pkgconfig_2.0.3         gson_0.1.0             
 [28] Matrix_1.7-3            R6_2.6.1                fastmap_1.2.0          
 [31] GenomeInfoDbData_1.2.14 digest_0.6.37           numDeriv_2016.8-1.1    
 [34] aplot_0.2.9             enrichplot_1.28.4       colorspace_2.1-2       
 [37] patchwork_1.3.2         ps_1.9.1                rprojroot_2.1.1        
 [40] irlba_2.3.5.1           RSQLite_2.4.3           filelock_1.0.3         
 [43] labeling_0.4.3          timechange_0.3.0        httr_1.4.7             
 [46] compiler_4.5.1          bit64_4.6.0-1           withr_3.0.2            
 [49] S7_0.2.0                BiocParallel_1.42.2     DBI_1.2.3              
 [52] R.utils_2.13.0          rappdirs_0.3.3          tools_4.5.1            
 [55] ape_5.8-1               httpuv_1.6.16           R.oo_1.27.1            
 [58] glue_1.8.0              callr_3.7.6             nlme_3.1-168           
 [61] GOSemSim_2.34.0         promises_1.3.3          grid_4.5.1             
 [64] getPass_0.2-4           reshape2_1.4.4          fgsea_1.34.2           
 [67] gtable_0.3.6            tzdb_0.5.0              R.methodsS3_1.8.2      
 [70] data.table_1.17.8       hms_1.1.3               xml2_1.4.0             
 [73] XVector_0.48.0          ggrepel_0.9.6           pillar_1.11.1          
 [76] babelgene_22.9          yulab.utils_0.2.1       later_1.4.4            
 [79] splines_4.5.1           treeio_1.32.0           BiocFileCache_2.16.2   
 [82] lattice_0.22-7          bit_4.6.0               tidyselect_1.2.1       
 [85] GO.db_3.21.0            Biostrings_2.76.0       knitr_1.50             
 [88] git2r_0.36.2            xfun_0.54               LaplacesDemon_16.1.6   
 [91] stringi_1.8.7           UCSC.utils_1.4.0        lazyeval_0.2.2         
 [94] ggfun_0.2.0             yaml_2.3.10             evaluate_1.0.5         
 [97] codetools_0.2-20        qvalue_2.40.0           ggplotify_0.1.3        
[100] cli_3.6.5               processx_3.8.6          jquerylib_0.1.4        
[103] dichromat_2.0-0.1       Rcpp_1.1.0              GenomeInfoDb_1.44.3    
[106] dbplyr_2.5.1            png_0.1-8               parallel_4.5.1         
[109] assertthat_0.2.1        blob_1.2.4              prettyunits_1.2.0      
[112] DOSE_4.2.0              tidytree_0.4.6          scales_1.4.0           
[115] crayon_1.5.3            rlang_1.1.6             fastmatch_1.1-6        
[118] KEGGREST_1.48.1