1. Molecular Basis of Recessive Dystrophic Epidermolysis Bullosa: Genotype/Phenotype Correlation in a Case of Moderate Clinical Severity
- Author
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John A. McGrath, Jouni Uitto, Hiroshi Shimizu, Takeji Nishikawa, and Angela M. Christiano
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Male ,Genotype ,Nonsense mutation ,Molecular Sequence Data ,Genes, Recessive ,Dermatology ,Biology ,Compound heterozygosity ,Biochemistry ,Anchoring fibrils ,Missense mutation ,Humans ,Allele ,mutation detection in genodermatoses ,Gene ,Molecular Biology ,Skin ,type VII collagen mutations ,Base Sequence ,integumentary system ,Cell Biology ,Molecular biology ,Epidermolysis Bullosa Dystrophica ,Restriction enzyme ,Microscopy, Electron ,Phenotype ,Child, Preschool ,Mutation ,molecular genetics of EB ,inheritable blistering diseases ,Heteroduplex - Abstract
Mutations within the gene encoding the anchoring fibril protein type VII collagen (COL7A1) have recently been established as the pathogenetic basis for the inherited blistering skin disorder, dystrophic epidermolysis bullosa. We report a patient with a moderately severe phenotype of recessive dystrophic epidermolysis bullosa. We report a patient with a moderately severe phenotype of recessive dystrophic epidermolysis bullosa, in whom COL7A1 mutations have been identified on both alleles. The patient is a 5-y-old Japanese male of nonconsanguineous parents, with clinical features including generalized trauma-induced blistering since birth, complete loss of nails, and partial fusion of the fingers and toes. Immunofluorescence microscopy examination of the dermal-epidermal junction in the patient's skin revealed near-normal intensity staining with an antitype VII collagen antibody (LH7:2). Transmission electron microscopy showed a reduced number of thin, poorly-formed anchoring fibrils. PCR amplification of genomic DNA, followed by heteroduplex analysis, and nucleotide sequencing demonstrated that the patient was a compound heterozygote for a nonsense mutation (E2858X) within the NC-2 domain of type VII collagen and a missense mutation (G2576R) within the type VII collagen triple helix. Both mutations were verified by restriction endonuclease digestion. Information about these mutations advances our understanding of genotype-phenotype correlations in dystrophic epidermolysis bullosa, and further delineates the mechanisms involved in dermal-epidermal dysadhesion.
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