TP53 and pachyonychia congenita: Seventy-nine PC samples were screened for mutations in exons 5, 6, 7 and 8 of TP53 gene (NG_017013) (HGNC: 11998), exons 4 and 5 of SPOP (NG_041815) (HGNC:11254) gene and exons 9 and 20 of PIK3CA (NG_012113) (HGNC:8975) gene.