Darier disease: first molecular study of a Portuguese family

Darier disease (DD) is a rare autosomal dominant condition characterized by skin lesions. Additionally, a wide range of neuropsychiatric symptoms is frequently reported in DD patients. This genodermatosis relies on mutations in the ATPase sarcoplasmic/endoplasmic reticulum Ca²⁺ transporting 2 (ATP2A2) gene, which encodes an ATPase responsible for pumping Ca²⁺ from the cytosol to the lumen of the ER.

Herein we studied the molecular aspect of a two-generation Portuguese family with DD history with clinical variability.

All exons and intron-exon borders of genomic ATP2A2, as well as coding ATP2A2, were sequenced. Relative levels of SERCA2 mRNA and protein were quantified by qPCR and western blotting, respectively.

The c.1287+1G > T variant was identified in all affected individuals, whereas the unaffected individual was shown to carry the wild-type ATP2A2 sequence in both alleles. This variant leads to the skipping of full exon 10, which consequently generates a frameshift originating a premature STOP codon in exon 11 (p.V395 = fs*19). Although the mutant mRNA seems to partially escape degradation, results suggest synthesis inhibition or immediate degradation of the mutant protein. Neuropsychiatric and other occurrences affecting certain patients are also reported.

This is the first study of DD in Portugal, the variant identified, previously described in a single Japanese patient, may be considered a pathogenic mutation, and haploinsufficiency the mechanism underlying DD pathology in these patients. This study also highlights the co-occurrence of neuropsychiatric features in DD.