In this study, the mutation prevalence in the FPC cohort was 3.7% for BRCA2, 2.5% for CDKN2A, 1.2% for BRCA1, and 0.6% for PALB2. Grant et al. conducted targeted sequencing of 13 genes associated with hereditary cancer syndromes or FPC for 290 PC probands, and showed the mutation prevalence was 2.6% (95% CI: 0–6.0) in cases with a history of PC in FDR and 4.0% (95% CI: 2.1–5.9) in those without any history [64]. The gene discussed is CDKN2A; the disease is pachyonychia congenita.