CDKN1B and pachyonychia congenita: Among the 38 PC patients and 31 APA patients who agreed to genetic analysis, except for one PC case carrying single nucleotide synonymous variant of AP2S1 gene, 8 APA patients (25.8%, 8/31) and 17 PC patients (44.7%, 17/38) were found to carry germline nonsynonymous rare variants of the candidate genes, including 14 CDC73, 4 GCM2, 3 MEN1, 2 RET, 1 GNA11 and 1 CDKN1B gene variants (Table 3).