BRCA1 and pachyonychia congenita: Studies of unselected patients with PC have detected BRCA1/2 mutations at a frequency of 4% to 7%.[4,5] For PC, the estimated cumulative risk by the age of 80 years for male subjects was 6.9% (95% confidence interval [CI] 3.8–10.0) and for female subjects 2.8% (0.9–4.7).[6] BRCA1 and BRCA2 proteins are significant for high-fidelity repair of double-strand breaks of DNA by the homologous recombination repair (HRR) pathway.