Specific TGM1 mutation profiles in bathing suit and self-improving collodion ichthyoses: phenotypic and genotypic data from 9 patients with dynamic phenotypes of autosomal recessive congenital ichthyosis.

BACKGROUND Bathing suit ichthyosis (BSI) and self-improving collodion ichthyosis (SICI) are 2 minor variants of generalized autosomal recessive congenital ichthyosis. Bathing suit ichthyosis is characterized by scaling of the skin in a bathing suit pattern, mainly limited to the trunk, whereas SICI is characterized by complete disappearance of the skin lesions. OBSERVATIONS We report genotypic and phenotypic data from a series of 9 patients who were collodion babies and developed BSI or SICI owing to mutations in the transglutaminase-1 gene (TGM1), including 3 previously unreported missense mutations. All of our patients with BSI or SICI carried at least 1 specific missense mutation in TGM1 concerning an arginine at position 307 or 315. In 2 patients, the disease evolved (BSI to SICI or BSI to autosomal recessive congenital ichthyosis). The remaining 7 patients exhibited a stable BSI phenotype after shedding of the collodion membrane. CONCLUSIONS This study highlights the possibility of variable evolution of the phenotype of patients with identical mutations in the same gene. Combined with data from the literature, these findings confirm the hypothesis that only a restricted spectrum of TGM1 mutations leads to a BSI and/or an SICI phenotype. This phenotypic variability also depends on other genetic and external factors.