In the initial hypothesis-generating phase the sub-group of advanced prostate cancer cases (n = 94) and an equal number of matched controls were genotyped for 384 SNPs including functional SNPs in selenoprotein genes and tagging SNPs covering the 25 selenoprotein genes and factors important for selenoprotein biosynthesis (Table S1) selected as described in Materials and Methods. The gene discussed is SELENOS; the disease is Familial prostate cancer.