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simPRS: Fast Simulation of Polygenic Risk Scores

Simulation of Polygenic Risk Score calculations allows to

  1. Select an optimal p-value threshold,
  2. Perform power analyses, and
  3. Estimate polygenicity of a phenotype.

Simulations are performed without direct simulations of the genotype and phenotype data. Instead, genome-wide association study (GWAS) summary statistics are generated directly from their finite sample distributions.

Installation

Try simPRS online

To try simPRS via an online shiny interface click here.

Install R package

To install simPRS directly from GitHub, run

if(!requireNamespace("devtools", quietly = TRUE))
    install.packages("devtools")
devtools::install_github("andreyshabalin/simPRS")

Sample code

Perform a single simulation

# Parameters
NTotalSNPs = 10000
NSignalSnps = 100
heritability = 0.2
signalDistr = "Same"
Ntrain = 10000
Ntest = 10000

signal = genSignal(
            NSignalSnps = NSignalSnps,
            NTotalSNPs = NTotalSNPs,
            heritability = heritability,
            signalDistr = signalDistr)
            
gwas = gwasFast(signal = signal, N = Ntrain)

prs = prsInf(
            gwasPV = gwas$pv,
            gwasBt = gwas$beta,
            signal = signal)

rci = rConfInt(r = prs$r, N = Ntest)

prsPlot(pv = prs$pv, r = prs$r, rci)

Average over 1000 simulations

Let's use the parameters and signal defined above

Nsim = 1000

prsA = prsMultitest(signal = signal, N = Ntrain, Nsim = Nsim)

rci = rConfInt(r = prsA$r, N = Ntest)

prsPlot(pv = prsA$pv, r = prsA$r, rci)