Iqbal et al. prospectively identified 8 PC cases from 3942 BRCA1 and 1147 BRCA2 mutation carriers, and reported that the relative PC risk compared with the general population was 2.6 (95% CI: 1.0–5.3) in BRCA1 carriers and 2.1 (95% CI: 0.4–7.0) in BRCA2 carriers [40]. This evidence concerns the gene BRCA1 and pachyonychia congenita.