PSA level associations with PCa risk variants may reflect a number of factors, including: (1) true disease-related increases in PSA levels; (2) the use of PSA levels to restrict controls in case-control studies of PCa; and/or 3) non-cancer related PSA levels that prompt additional biopsy screening (Supplementary Fig. 1). This evidence concerns the gene KLK3 and posterior cortical atrophy.