CDKN2A and pachyonychia congenita: Here, we confirm in an extended cohort of Italian PC patients, the high CDKN2A PV/LPV rate previously described [28,43], finding a total CDKN2A mutation rate of 4.5% (19/422), as high as the one conferred by BRCA1 and BRCA2 together (BRCA1 n = 6/422 and BRCA2 13/422).