SMAD4 and ocular melanoma: Interrogating our GWAS data set for candidate genes that have been previously proposed to be involved in pathogenesis of OM, we found 45 out of 82 genes demonstrated evidence of nominally significant association, with intragenic SNPs or nearby SNPs of P value<0.05; Supplementary Table 6), such as SMAD2, SMAD4, NELL1.