SMAD7 and Palmoplantar keratoderma: Associated genes included CDSN (psoriasis and peeling skin disease; Matsumoto et al., 2008; Oji et al., 2010), NCSTN (hidradenitis suppurativa; Pink et al., 2011), ELN (cutis laxa; Hadj‐Rabia et al., 2013), PEX7 (ichthyosis; van den Brink et al., 2003; Schmuth et al., 2013), SASH1 (palmoplantar keratoderma and alopecia; Courcet et al., 2015), and SMAD7 (hyperplasia and hyperkeratosis; He et al., 2002).