The proportion of somatic BRCA1 mutation carriers among patients with any stage PC was available from 10 articles, for a total of 3229 patients, and was equal to 1.20% (95% CI: 0.85–1.60), without significant heterogeneity (I2 = 0.00%; p = 0.7423) (Figure 2b). Here, BRCA1 is linked to pachyonychia congenita.