Rather than the standard distribution, the non-TCGA subset of ExAC is used because as a large collection of cancer samples, TCGA is likely to be enriched for mutations related to cancer predisposition; for example, germline pathogenic mutations were previously detected in TCGA ovarian cancer samples for BRCA1, BRCA2, and PALB2 (Kanchi et al. 2014). Here, BRCA2 is linked to cancer.