Clinical and molecular characterization of two patients with palmoplantar keratoderma-congenital alopecia syndrome type 2

Summary Palmoplantar keratoderma–congenital alopecia (PPKCA) syndrome is a rare genodermatosis, with two clinically recognizable forms: dominant (Type 1) and recessive (Type 2). Reports of only 18 patients have been published to date, and the molecular basis of the condition is unknown. We describe two cases with PPKCA Type 2 (PPKCA2), comprising a novel patient, originally reported as an example of autosomal ichthyosis follicularis–atrichia–photophobia syndrome, and the 6‐year follow‐up of a previously published case. Extensive molecular studies of both patients excluded mutations in all the known genes associated with PPK and partially overlapping syndromes. The striking similarities between these two patients confirm PPKCA2 as a discrete genodermatosis, of which the main features are congenital and universal alopecia, diffuse keratosis pilaris, facial erythema, and a specific PPK with predominant involvement of the fingertips and borders of the hands and feet, with evolution of sclerodactyly, contractures and constrictions. Clinical follow‐up of these patients has demonstrated progressive worsening of the hand involvement and attenuation of facial erythema.