The proportion of germline BRCA1 mutation carriers among patients with any stage PC was available from 31 articles, for a total of 32,525 patients, and was equal to 0.73% (95% confidence interval, CI: 0.51–1.00), with significant heterogeneity (I2 = 81.19%; p < 0.0001) (Figure 2a). Here, BRCA1 is linked to pachyonychia congenita.