Phenotype, genotype and ultrastructural findings in a pedigree with autosomal recessive congenital ichthyosis / 中华皮肤科杂志

ABSTRACT

Objective To investigate the clinical phenotype, genotype and ultrastructural features in a pedigree with autosomal recessive congenital ichthyosis. Methods Patients were examined for clinical manifestation. PCR was carried out to amplify all the 15 exons and adjacent splice sites of TGM1 gene followed by bidirectional sequencing. Skin samples were taken by biopsy from the back of the proband, fixed in 3% glu-taraldehyde for transmission electron microscopy. Results The proband presented an intermediate clinical phenotype between lamellar ichthyosis (LI) and non-bullous congenital ichthyosiform erythroderma (NCIE), while his brother manifested as a collodion baby. A C551T heterozygous mutation which located in the third exon of TGM1 gene and resulted in a substitution of arginine by cysteine at codon 143 (R143C), was detected in the proband, his brother and father. Meanwhile, another heterozygous C-to-T transition at position 759 causing a substitution of serine by phenylalanine at codon 212 (S212F), was noted in the proband, his brother and mother. Electron microscopy revealed not only features of ichthyosis congenital type Ⅲ but also those of ichthyosis congenital type Ⅱ in lesions of the proband. Conclusions The patients in this pedigree carry compound heterozygous mutations, i.e. R143C, a hot missense mutation, as well as a de novo mutation S212F. The proband, who harbors mutations in the TGM1 gene, shows electron microscopic features characteristic not only of ichthyosis congenital type Ⅱ but also of ichthyosis congenital type Ⅲ.