Background: Mutations in the type VII collagen gene (COL7A1) are responsible for dominant and recessive forms of dystrophic epidermolysis bullosa (DEB). These mutations are usually specific for individual families; on...Background: Mutations in the type VII collagen gene (COL7A1) are responsible for dominant and recessive forms of dystrophic epidermolysis bullosa (DEB). These mutations are usually specific for individual families; only a few cases of recurring mutations have been identified. Objectives: Forty- three unrelated Hungarian and German patients with different DEB phenotypes were screened for novel and recurrent COL7A1 mutations. Methods: All patients were classified based on clinical and genetic findings,skin immunofluorescent antigen mapping, and electron microscopic studies. Mutation analysis was performed by amplification of genomic DNA with polymerase chain reaction using COL7A1- specific primers, heteroduplex analysis, and direct nucleotide sequencing. Restriction endonuclease digestion was used for family screening and mutation verification. Results: In this group of patients, the splice- site mutation 425A → G was observed frequently, in 11 of 86 alleles (12- 8% ), once in homozygous form and in nine cases in heterozygous form. One of 100 control alleles from clinically unaffected individuals also carried the mutation. We also identified three novel mutations: the 976- 3C → A splice- site mutation, and the 4929 del T and 8441- 15del20 deletions. Conclusions: High recurrence of the splice- site mutation 425A → G in central European patients with DEB should be taken into account when designing COL7A1 mutation detection strategies. Reporting of three novel COL7A1 mutations in this study further emphasizes the molecular heterogeneity of DEB and provides more information for studies on genotype- phenotype correlations in different DEB subtypes.展开更多
Dystrophic epidermolysis bullosa (DEB), a heterogeneous hereditary skin disorder characterized by trauma-induced blistering and scarring, affects thousands of families world wide. The clinical manifestations extend fr...Dystrophic epidermolysis bullosa (DEB), a heterogeneous hereditary skin disorder characterized by trauma-induced blistering and scarring, affects thousands of families world wide. The clinical manifestations extend from minor nail dystrophy to severe life-threatening blistering, making early molecular diagnosis and prognostication of utmost importance for the affected families. DEB is caused by mutations in the COL7A1 gene encoding collagen VII in the skin. Molecular diagnostics and genotype-phenotype correlations in DEB remain complex owing to the gene structure, large variety of mutations, high rate of novel mutations, complex protein structure and assembly, and the heterogeneity of phenotypes. Here, we report an efficient strategy for COL7A1mutation detection using direct automated DNA sequencing and implementation of software tools. With this approach, COL7A1 mutations of 41 DEB families were disclosed. Twenty-four mutations were novel and two recurrent. Elucidation of biological consequences of the mutations helped define disease mechanisms, but also revealed several unusual genotypic and/or phenotypic constellations, which impeded the diagnostics and prognostication. In addition, the studies disclosed a de novo mutation in recessive DEB and two new polymorphisms in the COL7A1 gene.展开更多
Mutations in the type VII collagen gene (COL7A1) cause autosomal recessive and autosomal dominant inherited dystrophic epidermolysis bullosa (DEB). We report a family with three individuals who present blistering, sca...Mutations in the type VII collagen gene (COL7A1) cause autosomal recessive and autosomal dominant inherited dystrophic epidermolysis bullosa (DEB). We report a family with three individuals who present blistering, scarring, hypo- and hyperpigmentation, and nail dystrophy suggestive for DEB.Whereas father and son carry a 5;13 translocation, the daughter shows a normal karyotype. Segregation analysis revealed that all affected family members inherited the same COL7A1 allele. Mutation analysis disclosed a heterozygous missense mutation, c.6227G > A (p.G2076D), in COL7A1 in all affected individuals. Delineation of the translocation breakpoints showed that the ERBB2IP (erbb2 interacting protein or Erbin) gene is disrupted in 5q13.1 and GPC6 in 13q32. GPC6 encodes glypican 6 belonging to a family of cell surface heparan sulfate proteoglycans. The binding partners of Erbin,BP230 (BPAG1)- and the integrin β 4 subunit, both involved in hemidesmosome (HD) function, and the presence of Erbin in HD suggested that it plays a role in establishment and maintenance of cell-basement membrane adhesions. However, loss of function of one ERBB2IP copy or expression of a putative novel ERBB2IP fusion protein did not apparently modulate the DEB phenotype in both translocation patients. Nonetheless, one cannot yet exclude that ERBB2IP is a candidate for human blistering disorders such as epidermolysis bullosa.展开更多
文摘Background: Mutations in the type VII collagen gene (COL7A1) are responsible for dominant and recessive forms of dystrophic epidermolysis bullosa (DEB). These mutations are usually specific for individual families; only a few cases of recurring mutations have been identified. Objectives: Forty- three unrelated Hungarian and German patients with different DEB phenotypes were screened for novel and recurrent COL7A1 mutations. Methods: All patients were classified based on clinical and genetic findings,skin immunofluorescent antigen mapping, and electron microscopic studies. Mutation analysis was performed by amplification of genomic DNA with polymerase chain reaction using COL7A1- specific primers, heteroduplex analysis, and direct nucleotide sequencing. Restriction endonuclease digestion was used for family screening and mutation verification. Results: In this group of patients, the splice- site mutation 425A → G was observed frequently, in 11 of 86 alleles (12- 8% ), once in homozygous form and in nine cases in heterozygous form. One of 100 control alleles from clinically unaffected individuals also carried the mutation. We also identified three novel mutations: the 976- 3C → A splice- site mutation, and the 4929 del T and 8441- 15del20 deletions. Conclusions: High recurrence of the splice- site mutation 425A → G in central European patients with DEB should be taken into account when designing COL7A1 mutation detection strategies. Reporting of three novel COL7A1 mutations in this study further emphasizes the molecular heterogeneity of DEB and provides more information for studies on genotype- phenotype correlations in different DEB subtypes.
文摘Dystrophic epidermolysis bullosa (DEB), a heterogeneous hereditary skin disorder characterized by trauma-induced blistering and scarring, affects thousands of families world wide. The clinical manifestations extend from minor nail dystrophy to severe life-threatening blistering, making early molecular diagnosis and prognostication of utmost importance for the affected families. DEB is caused by mutations in the COL7A1 gene encoding collagen VII in the skin. Molecular diagnostics and genotype-phenotype correlations in DEB remain complex owing to the gene structure, large variety of mutations, high rate of novel mutations, complex protein structure and assembly, and the heterogeneity of phenotypes. Here, we report an efficient strategy for COL7A1mutation detection using direct automated DNA sequencing and implementation of software tools. With this approach, COL7A1 mutations of 41 DEB families were disclosed. Twenty-four mutations were novel and two recurrent. Elucidation of biological consequences of the mutations helped define disease mechanisms, but also revealed several unusual genotypic and/or phenotypic constellations, which impeded the diagnostics and prognostication. In addition, the studies disclosed a de novo mutation in recessive DEB and two new polymorphisms in the COL7A1 gene.
文摘Mutations in the type VII collagen gene (COL7A1) cause autosomal recessive and autosomal dominant inherited dystrophic epidermolysis bullosa (DEB). We report a family with three individuals who present blistering, scarring, hypo- and hyperpigmentation, and nail dystrophy suggestive for DEB.Whereas father and son carry a 5;13 translocation, the daughter shows a normal karyotype. Segregation analysis revealed that all affected family members inherited the same COL7A1 allele. Mutation analysis disclosed a heterozygous missense mutation, c.6227G > A (p.G2076D), in COL7A1 in all affected individuals. Delineation of the translocation breakpoints showed that the ERBB2IP (erbb2 interacting protein or Erbin) gene is disrupted in 5q13.1 and GPC6 in 13q32. GPC6 encodes glypican 6 belonging to a family of cell surface heparan sulfate proteoglycans. The binding partners of Erbin,BP230 (BPAG1)- and the integrin β 4 subunit, both involved in hemidesmosome (HD) function, and the presence of Erbin in HD suggested that it plays a role in establishment and maintenance of cell-basement membrane adhesions. However, loss of function of one ERBB2IP copy or expression of a putative novel ERBB2IP fusion protein did not apparently modulate the DEB phenotype in both translocation patients. Nonetheless, one cannot yet exclude that ERBB2IP is a candidate for human blistering disorders such as epidermolysis bullosa.
