KRT9 and pachyonychia congenita: Various cutaneous disorders are identified with mutated keratin proteins namely epidermolysis bullosa simplex (EBS) (K5, K14), ichthyosis (Kl, K2, and K10), palmoplantar keratoderma (K9), type I pachyonychia congenita (PC) (K6a and K16), seven type II pachyonychia congenita (K6b and K17), and monilethrix (K81, K83, and K86).