Hello, I am sorry for posting this question related to TWMR but it seems I can nto proceed with this. Hopefully this post now will make sense. So I am running this code: https://github.com/eleporcu/TWMR/blob/master/MR.R I made this change in code so that I can run it like this: Rscript MR.R ENSG00000154803 the change of the beginning of code is this: cmd_args <- commandArgs(TRUE) if (length(cmd_args) == 0L) stop("No arguments specified.") print(cmd_args) gene<-cmd_args[length(cmd_args)] ## Last argument is the 'gene' Ngwas<-239087 N_eQTLs<-32000 out<-c("gene","alpha","SE","P","Nsnps","Ngene") file<-paste(gene,"matrix",sep=".") if (!file.exists(file)) stop("File not found: ", file) filecluster<-read.table(file,header=T,sep=" ",dec=".") beta<-as.matrix(filecluster[,2:(length(filecluster[1,])-1)]) The error I am getting when I run the code with my data is: [1] "ENSG00000154803" Error in solve.default(C) : Lapack routine dgesv: system is exactly singular: U[15,15] = 0 Calls: solve -> solve.default Execution halted I loaded my ENSG00000154803.ld file in R as matrix (a) and: library(matrixcalc) is.singular.matrix(a, tol = 1e-08) TRUE Seems that my matrix is singular. What do you advice in this case? Thanks Ana