dbSNP v149 and converted to GRCh38 coordinates using CrossMap [58] with chain files from the UCSC Genome Browser (https://genome.ucsc.edu/). Non-SNP positions and duplicated sites identified by checkVCF (https://github.com/zhanxw/checkVCF) were filtered out, as were sites with an imputation r2 less than 0.8, minor allele frequency less than 0.05, or Hardy-Weinberg Equilibrium violation P values less than 1 × 10− 4. Genotypes from DNA were compared with those from RNA sequencing to confirm matching of genotype and gene expression measures for each sample.
