Peeling Skin, Leukonychia, Acral Punctate Keratoses, Cheilitis and Knuckle Pads (PLACK) Syndrome: An Updated Review of Cases and Identification of a Recurrent CAST Variant in Two Patients.

Peeling skin, leukonychia, acral punctate keratoses, cheilitis, and knuckle pads (PLACK) syndrome (OMIM616295) is an exceptionally rare autosomal recessive genodermatosis caused by loss-of-function pathogenic variants in the CAST gene, encoding calpastatin. A total of 19 cases have been described in 12 articles, among families with unique de novo genetic variants of CAST. We describe two pediatric PLACK cases with a homozygous loss-of-function CAST variant (c.571G>T, p.Gly191Ter) which represents the only recurrent genetic variant of PLACK syndrome reported in the literature.