SMAD4 and pachyonychia congenita: Evaluating 456 specimens of resected PC by a combination of whole-genome sequencing and deep-exome sequencing, Bailey et al. identified genetic mutations particularly of KRAS in 92%, cell cycle checkpoint mutations as TP53 and CDKN2A in 78%, aberrations in TGF beta signaling as SMAD4, TGFBR1, and Activin A receptor 1B in 47%, mutations leading to histone modification in 24%, mutations in the Breast Cancer Gene (BRCA) pathway in 17%, and mutations in the ATP-dependent chromatin remodeling complex as AT-rich interaction domain 1A (ARID1A) in 14% (Bailey et al. 2016).