Identification of a Novel COL17A1 Compound Heterozygous Mutation in a Chinese Girl with Non-Herlitz Junctional Epidermolysis Bullosa

摘要

Summary:Non-Herlitz junctional epidermolysis bullosa(JEB-nH),an autosomal recessive bullous genodermatosis,is characterized by generalized skin blistering from birth onward,dental anomalies,universal alopecia and nail dystrophy.The underlying defect is mutation of the COLI7AI gene encoding the type XVⅡcollagen,resulting in losing structure for attachment of basal epithelial cells to the matrix.In present study,we described one case of congenitally affected female child aged 10 years,with skin blistering.Dermatologic examination revealed sparse,mild blisters on the face and hand,with profound enamel pitting of the teeth.Skin biopsy from proband''s bullous skin displayed subepidermal bulla formation without acantholysis.The immunofluorescence of anti-type XVⅡcollagen antibody staining showed loss of type XVⅡcollagen staining at the basement membrane zone.A combination of whole exome sequencing(WES)and Sanger sequencing revealed the novel heterozygous mutations(C.4324C>T;p.Q1442^*and C.I 834G>C;p.G612R)in COLI7AI gene,which could be associated with the observed JEB-nH.One allele had a novel nonsense mutation(c.4324C>T;p.Q1442^*),resulting in nonsense-mediated mRNA decay and truncated collagen XVⅡ;the other allelc had a novel misscnse mutation of c.1834G>C;p.G612R in exon 22,causing a glycine-to-arginine substitution in the Gly-X-Y triple helical repeating motifs and decreasing the thermal stability of collagen XVⅡ.Our findings indicate that the genetic test based on WES can be useful in diagnosing JEB-nH patients.The novel pathogenic mutations identified would further expand our understanding of the mutation spectrum of COLI7AI gene in association with the inherited blistering diseases.