The RR estimates from studies that selected participants for PCa diagnosis at a young age, PCa family history or aggressive PCa were higher than estimates from studies in unselected participants (BRCA1: test for subgroup differences, P = 0.056, BRCA2: test for subgroup differences, P < 0.001; Supplementary Table S2). This evidence concerns the gene BRCA1 and posterior cortical atrophy.