The proportion of germline BRCA1/2 mutation carriers among patients with metastatic PC was available from 11 articles, for a total of 11,670 patients, and was equal to 5.84% (95% CI: 3.72–8.41), with significant heterogeneity (I2 = 93.61%; p < 0.0001) (Figure 4c). The gene discussed is BRCA1; the disease is pachyonychia congenita.