The proportion of somatic BRCA1/2 mutation carriers among patients with metastatic PC was available from six articles, for a total of 1384 patients, and was equal to 10.94% (95% CI: 8.73–13.36), without significant heterogeneity (I2 = 29.07%; p = 0.2170) (Figure 4d). The gene discussed is BRCA1; the disease is pachyonychia congenita.