151
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Kon A, Pulkkinen L, Ishida-Yamamoto A, Hashimoto I, Uitto J. Novel COL7A1 mutations in dystrophic forms of epidermolysis bullosa. J Invest Dermatol 1998; 111:534-7. [PMID: 9740253 DOI: 10.1046/j.1523-1747.1998.00326.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mutations in the type VII collagen gene (COL7A1) have been shown to underlie different variants of dystrophic epidermolysis bullosa (DEB). Examination of the genetic database indicates that most of the mutations are family specific, with few recurrent mutations. To facilitate further refinement of genotype/phenotype correlations in DEB, we have examined a cohort of nine families with DEB (seven recessively and two dominantly inherited) by a mutation detection strategy based on polymerase chain reaction amplification of COL7A1 genomic sequences, followed by heteroduplex scanning and direct nucleotide sequencing. The results revealed 16 allelic mutations, 11 of them being novel, previously unpublished. The genetic information was also used for prenatal testing in a family at risk for recurrence of a severe, Hallopeau-Siemens type of RDEB. These data contribute to the expanding database of COL7A1 mutations in DEB.
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Affiliation(s)
- A Kon
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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152
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Galligan P, Listwan P, Siller GM, Rothnagel JA. A novel mutation in the L12 domain of keratin 5 in the Köbner variant of epidermolysis bullosa simplex. J Invest Dermatol 1998; 111:524-7. [PMID: 9740251 DOI: 10.1046/j.1523-1747.1998.00308.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have identified a novel mutation within the linker L12 region of keratin 5 (K5) in a family with the Köbner variant of epidermolysis bullosa simplex. The pattern of inheritance of the disorder in this family is consistent with an autosomal dominant mode of transmission. Affected individuals develop extensive and generalized blistering at birth or early infancy but in later years clinical manifestations are largely confined to palmoplantar surfaces. Direct sequencing of polymerase chain reaction products revealed a T to C transition within codon 323 of K5 in affected individuals, resulting in a valine to alanine substitution of the seventh residue within the L12 linker domain. This mutation was not observed in unaffected family members or in 100 K5 alleles of unrelated individuals with normal skin. The other critical regions of K5 and K14 were unremarkable in this family except for common polymorphisms that have been previously described. The valine at position 7 of the L12 domain is absolutely conserved in all type II keratins, and in other intermediate filament subunits as well, which suggests that this residue makes an important contribution to filament integrity. Secondary structure analysis revealed that alanine at this position markedly reduces both the hydrophobicity and the beta-sheet nature of the L12 domain. This is the first report of a mutation at this position in an intermediate filament subunit and reinforces the importance of this region to filament biology.
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Affiliation(s)
- P Galligan
- Department of Biochemistry and the Center for Molecular and Cellular Biology, University of Queensland, Brisbane, Australia
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153
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Mellerio JE, Eady RA, Atherton DJ, Lake BD, McGrath JA. E210K mutation in the gene encoding the beta3 chain of laminin-5 (LAMB3) is predictive of a phenotype of generalized atrophic benign epidermolysis bullosa. Br J Dermatol 1998; 139:325-31. [PMID: 9767254 DOI: 10.1046/j.1365-2133.1998.02377.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pathogenetic mutations in the genes encoding the hemidesmosome-anchoring filament complex proteins, laminin-5 and the 180 kDa bullous pemphigoid antigen, have been identified in patients with the inherited mechanobullous disease, junctional epidermolysis bullosa (EB). Furthermore, there is some evidence to suggest that precise definition of the nature of mutations in these genes may correlate to specific phenotypes of disease. We report three junctional EB patients who carry an identical missense mutation, E210K, on one allele of the gene encoding the beta3 subunit chain of laminin-5 (LAMB3) in addition to different nonsense mutations on the second allele. Two of the patients are adults and display a specific phenotype of non-lethal junctional EB known as generalized atrophic benign EB, which is associated with trauma-induced blisters, nail dystrophy and alopecia. As the third patient is a young child with fewer features of this subtype to date, identification of E210K in combination with a nonsense LAMB3 mutation may be predictive of the subsequent development of a generalized atrophic benign EB phenotype both in this child and in other junctional EB patients with the E210K mutation. Identification of this particular mutation has important implications for clinical management and counselling.
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Affiliation(s)
- J E Mellerio
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology (UMDS), St Thomas' Hospital, London SE1 7EH, U.K
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154
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Torrelo A, Valverde E, Zambrano A. Informativeness of polymorphic markers for prenatal diagnosis of recessive dystrophic epidermolysis bullosa in Spanish families at risk. J Dermatol Sci 1998; 17:233-8. [PMID: 9697052 DOI: 10.1016/s0923-1811(98)00020-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
DNA polymorphic markers are useful for the prenatal diagnosis of generalized recessive dystrophic epidermolysis bullosa (GRDEB) in families with at least one child affected with the disease. It is our policy to investigate families at risk using DNA polymorphic markers before a new pregnancy is intended, to inform about the real chances of offering an accurate prenatal diagnosis based on such DNA markers. We have analysed 10 Spanish families with at least one child affected with GRDEB with three different markers linked to the type VII collagen gene: the intragenic PvuII RFLP, and two markers mapped close to the COL7A1 gene, an MspI polymorphism belonging to the anonymous marker D3S2, and the microsatellite D3S1100. The PvuII marker was partially informative in two of 10 families, and was fully informative in three additional families; The MspI marker was partially informative in two of 10 families, and was fully informative in three additional families; it was not informative in five families. The D3S1100 microsatellite was partially informative in two out of 10 families, and fully informative in the other eight families. Combination of all three markers was shown to be partially informative in one family and fully informative in the remaining nine families. Using this combination of markers, we have inferred an accurate linkage-based prenatal diagnosis of GRDEB in four pregnancies. Surprisingly, the intragenic marker PvuII had a very limited usefulness, despite the results of previous studies; the microsatellite D3S1100 offered the best results for an eventual prenatal diagnosis of GRDEB. However, families at risk should be informed that extragenic markers may fail due to the possibility of recombination, estimated as 5% for D3S1100.
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Affiliation(s)
- A Torrelo
- Department of Dermatology, Hospital del Niño Jesús, Madrid, Spain
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155
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Muramatsu T, Hatoko M, Shirai T, Vanittanakom P. A case of dystrophic epidermolysis bullosa: surgical treatment for hand contracture using abdominal skin flap. J Dermatol 1998; 25:443-7. [PMID: 9714977 DOI: 10.1111/j.1346-8138.1998.tb02432.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The patient was a 15-year-old male. Since birth, he has suffered from recurrent blistering, especially on the extremities. Histology and electron microscopic finding of the cutaneous lesions were compatible with those of dystrophic epidermolysis bullosa. Contracture and mobility limitation of the hands had gradually deteriorated. Prior to the admission to our clinic, both hands' contracture had been surgically treated 4 times in another hospital; however, after treatment with skin grafting, hand contracture recurred each time within one year. This time, surgical treatment was carried out for his left hand contracture using an abdominal skin flap under local anesthesia. In comparison with the free skin graft the abdominal skin flap improved hand contracture for a longer time. Abdominal skin flap is recommended as a method for the treatment of hand contracture of patients with dystrophic epidermolysis bullosa.
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Affiliation(s)
- T Muramatsu
- Department of Dermatology, Nara Medical University, Japan
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156
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Maman E, Maor E, Kachko L, Carmi R. Epidermolysis bullosa, pyloric atresia, aplasia cutis congenita: Histopathological delineation of an autosomal recessive disease. ACTA ACUST UNITED AC 1998. [DOI: 10.1002/(sici)1096-8628(19980630)78:2<127::aid-ajmg6>3.0.co;2-l] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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157
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Dellambra E, Vailly J, Pellegrini G, Bondanza S, Golisano O, Macchia C, Zambruno G, Meneguzzi G, De Luca M. Corrective transduction of human epidermal stem cells in laminin-5-dependent junctional epidermolysis bullosa. Hum Gene Ther 1998; 9:1359-70. [PMID: 9650620 DOI: 10.1089/hum.1998.9.9-1359] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Laminin-5 is composed of three distinct polypeptides, alpha3, beta3, and gamma2, which are encoded by three different genes, LAMA3, LAMB3, and LAMC2, respectively. We have isolated epidermal keratinocytes from a patient presenting with a lethal form of junctional epidermolysis bullosa characterized by a homozygous mutation of the LAMB3 gene, which led to complete absence of the beta3 polypeptide. In vitro, beta3-null keratinocytes were unable to synthesize laminin-5 and to assemble hemidesmosomes, maintained the impairment of their adhesive properties, and displayed a decrease of their colony-forming ability. A retroviral construct expressing a human beta3 cDNA was used to transduce primary beta3-null keratinocytes. Clonogenic beta3-null keratinocytes were transduced with an efficiency of 100%. Beta3-transduced keratinocytes were able to synthesize and secrete mature heterotrimeric laminin-5. Gene correction fully restored the keratinocyte adhesion machinery, including the capacity of proper hemidesmosomal assembly, and prevented the loss of the colony-forming ability, suggesting a direct link between adhesion to laminin-5 and keratinocyte proliferative capacity. Clonal analysis demonstrated that holoclones expressed the transgene permanently, suggesting stable correction of epidermal stem cells. Because cultured keratinocytes are used routinely to make autologous grafts for patients suffering from large skin or mucosal defects, the full phenotypic reversion of primary human epidermal stem cells defective for a structural protein opens new perspectives in the long-term treatment of genodermatoses.
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Affiliation(s)
- E Dellambra
- Laboratory of Tissue Engineering, I.D.I.-IRCCS, Istituto Dermopatico dell'Immacolata, Rome, Italy
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158
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Dabelsteen E. Molecular biological aspects of acquired bullous diseases. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 1998; 9:162-78. [PMID: 9603234 DOI: 10.1177/10454411980090020201] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bullous diseases of the oral mucosa and skin were originally classified on the basis of clinical and histological criteria. The discovery of autoantibodies in some of these patients and the introduction of molecular biology have resulted in a new understanding of the pathological mechanisms of many of the bullous lesions. In this article, updated topics of the immune-mediated bullous lesions which involve oral mucosa and skin are reviewed. Pemphigus antigens, which are desmosomal-associated proteins and belong to the cadherin superfamily of cell adhesion proteins, have been isolated, and their genes have been cloned. The antigens which react with autoantibodies from patients with bullous pemphigoid, cicatricial pemphigoid, acquired epidermolysis bullosa, and linear IgA disease are all proteins of the hemidesmosome basement membrane complex. Interestingly, most of the antigens also appear to be the target for mutations seen in patients with the inherited type of epidermolysis bullosa in which bullous lesions are a prominent clinical feature.
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Affiliation(s)
- E Dabelsteen
- Department of Oral Diagnostics, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Denmark
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159
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Mazzanti C, Gobello T, Posteraro P, Paradisi M, Meneguzzi G, Chinni L, Zambruno G. 180-kDa bullous pemphigoid antigen defective generalized atrophic benign epidermolysis bullosa: report of four cases with an unusually mild phenotype. Br J Dermatol 1998; 138:859-66. [PMID: 9666835 DOI: 10.1046/j.1365-2133.1998.02226.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Generalized atrophic benign epidermolysis bullosa (GABEB) is a rare variant of non-lethal junctional epidermolysis bullosa characterized by generalized skin blistering healing with atrophy and by atrophic alopecia with onset in childhood. Other features include mild mucosal blistering, dental abnormalities and nail dystrophy. We report four additional cases of GABEB from two families originating from the same isolated village. The patients shared an unusually mild clinical phenotype with cutaneous blisters strictly limited to trauma sites and rare occurrence of oral mucosal lesions. Scalp, eyelash and eyebrow alopecia was present in only two cases. Immunofluorescence studies showed a markedly reduced expression of the 180-kDa bullous pemphigoid antigen (BP180), and northern analysis of cultured keratinocytes indicated that the gene encoding for BP180 is affected in these GABEB patients.
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Affiliation(s)
- C Mazzanti
- VIII Department of Dermatology, Istituto Dermopatico dell'Immacolata, IRCCS, Rome, Italy
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160
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Salas-Alanis JC, Mellerio JE, Amaya-Guerra M, Ashton GH, Eady RA, McGrath JA. Frameshift mutations in the type VII collagen gene (COL7A1) in five Mexican cousins with recessive dystrophic epidermolysis bullosa. Br J Dermatol 1998; 138:852-8. [PMID: 9666834 DOI: 10.1046/j.1365-2133.1998.02225.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dystrophic epidermolysis bullosa (DEB) is caused by mutations in the type VII collagen gene (COL7A1). In this study, we assessed the molecular basis of recessive DEB in five affected individuals from two Mexican families. Both fathers of the affected children were first cousins. Genomic DNA was extracted from peripheral blood samples and assessed for COL7A1 mutations by polymerase chain reaction (PCR) amplification, heteroduplex analysis and direct automated sequencing of PCR products displaying heteroduplex bandshifts. In one family, we identified a homozygous 1 bp insertion of a G nucleotide in exon 19 of COL7A1, designated 2470insG, in three affected sisters. This mutation causes a frameshift and a premature termination codon on both alleles 178 bp downstream from the insertion; both parents were shown to be heterozygous carriers of this mutation. In the second family, the father of the other two affected children was also found to be a heterozygous carrier of this frameshift mutation. In addition, his unrelated partner was shown to be a heterozygous carrier of a different COL7A1 frameshift mutation, an insertion of a T nucleotide in exon 32, designated 3948insT. This mutation also results in a premature termination codon, 126 bp downstream from the insertion. Both affected children were compound heterozygotes for the 2470insG/3948insT mutations in COL7A1. Overall, these molecular findings offer a genetic explanation for the skin fragility in these related Mexican patients with recessive DEB. Immediate benefits from elucidation of the mutations include assessment of carrier status in other members of the family and the feasibility of DNA-based prenatal testing in subsequent pregnancies.
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Affiliation(s)
- J C Salas-Alanis
- Servicios Médicos de la Universidad Autonóma de Nuevo León, Monterrey, Mexico
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161
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Goldstein AM, Davenport T, Sheridan RL. Junctional epidermolysis bullosa: diagnosis and management of a patient with the Herlitz variant. J Pediatr Surg 1998; 33:756-8. [PMID: 9607491 DOI: 10.1016/s0022-3468(98)90210-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A case of Herlitz-type epidermolysis bullosa (EB) is reported. The baby was born after a normal, full-term pregnancy with blisters on his extremities. Over the next several months, progressive skin sloughing involving 95% of his body surface area developed, including gastrointestinal, laryngeal, tracheobronchial, and corneal involvement. The diagnosis of junctional EB, Herlitz type, was made using clinical, electron microscopic, and immunohistochemical criteria. Despite meticulous wound care, aggressive nutritional support, and continuous antimicrobial therapy, the baby died at 9 months of age. This report discusses the presentation, complications, and management of this unusual and tragic disease.
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Affiliation(s)
- A M Goldstein
- Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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162
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Takizawa Y, Pulkkinen L, Shimizu H, Lin L, Hagiwara S, Nishikawa T, Uitto J. Maternal uniparental meroisodisomy in the LAMB3 region of chromosome 1 results in lethal junctional epidermolysis bullosa. J Invest Dermatol 1998; 110:828-31. [PMID: 9579554 DOI: 10.1046/j.1523-1747.1998.00186.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Herlitz junctional epidermolysis bullosa (OMIM#226700) is a lethal, autosomal recessive blistering disorder caused by mutations in one of the three genes LAMA3, LAMB3, or LAMC2, encoding the constitutive polypeptide subunits of laminin 5. In this study, we describe a patient homozygous for a novel nonsense mutation Q936X in exon 19 of LAMB3, which has been mapped to chromosome 1q32. The patient was born with extensive blistering and demonstrated negative immunofluorescence staining for laminin 5, and transmission electron microscopy revealed tissue separation within lamina lucida of the dermal-epidermal junction, diagnostic of Herlitz junctional epidermolysis bullosa. The mother of the proband was found to be a heterozygous carrier for this mutation, whereas the father demonstrated the wild-type LAMB3 allele only. Nonpaternity was excluded by 13 microsatellite markers in six different chromosomes. Genotype analysis using 28 microsatellite markers spanning chromosome 1 revealed that the patient had maternal primary heterodisomy, as well as meroisodisomy within two regions of chromosome 1, one on 1p and the other one on 1q, the latter region containing the maternal LAMB3 mutation. These results suggest that Herlitz junctional epidermolysis bullosa in this patient developed as a result of reduction to homozygosity of the maternal LAMB3 mutation on chromosome 1q32.
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Affiliation(s)
- Y Takizawa
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Philadelphia, Pennsylvania 10107, USA
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163
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Matsui C, Pereira P, Wang CK, Nelson CF, Kutzkey T, Lanigan C, Woodley D, Morohashi M, Welsh EA, Hoeffler WK. Extent of laminin-5 assembly and secretion effect junctional epidermolysis bullosa phenotype. J Exp Med 1998; 187:1273-83. [PMID: 9547338 PMCID: PMC2212220 DOI: 10.1084/jem.187.8.1273] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/1997] [Revised: 02/05/1998] [Indexed: 01/18/2023] Open
Abstract
Junctional epidermolysis bullosa (JEB) is an autosomal recessive skin blistering disease with both lethal and nonlethal forms, with most patients shown to have defects in laminin-5. We analyzed the location of mutations, gene expression levels, and protein chain assembly of the laminin-5 heterotrimer in six JEB patients to determine how the type of genetic lesion influences the pathophysiology of JEB. Mutations within laminin-5 genes were diversely located, with the most severe forms of JEB correlating best with premature termination codons, rather than mapping to any particular protein domain. In all six JEB patients, the laminin-5 assembly intermediates we observed were as predicted by our previous work indicating that the alpha3beta3gamma2 heterotrimer assembles intracellularly via a beta3gamma2 heterodimer intermediate. Since assembly precedes secretion, mutations that disrupt protein-protein interactions needed for assembly are predicted to limit the secretion of laminin-5, and likely to interfere with function. However, our data indicate that typically the most severe mutations diminish mRNA stability, and serve as functional null alleles that block chain assembly by resulting in either a deficiency (in the nonlethal mitis variety) or a complete absence (in lethal Herlitz-JEB) of one of the chains needed for laminin-5 heterotrimer assembly.
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Affiliation(s)
- C Matsui
- Department of Dermatology, Stanford University School of Medicine, Stanford, California 94305, USA
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164
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Mellerio JE, Denyer JE, Atherton DJ, Eady RA, McGrath JA. Prognostic implications of determining 180 kDa bullous pemphigoid antigen (BPAG2) gene/protein pathology in neonatal junctional epidermolysis bullosa. Br J Dermatol 1998; 138:661-6. [PMID: 9640376 DOI: 10.1046/j.1365-2133.1998.02182.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Epidermolysis bullosa (EB) in neonates is often difficult to characterize, both in terms of making a precise diagnosis and in being able to comment accurately on the prognosis for the affected child. We present a case of a neonate with inherited mucocutaneous fragility and failure to thrive and detail our laboratory approach for classifying the subtype of EB in this child. Mutational analysis revealed a homozygous non-sense mutation in the gene encoding the 180 kDa bullous pemphigoid antigen, also known as type XVII collagen, predicting a non-lethal form of junctional EB. Identification of the underlying molecular pathology in this case was of use in improving diagnosis, classification, management and counselling.
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Affiliation(s)
- J E Mellerio
- Department of Cell Pathology, St John's Institute of Dermatology (UMDS), St Thomas' Hospital, London, U.K
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165
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Pulkkinen L, Uitto J. Hemidesmosomal variants of epidermolysis bullosa. Mutations in the alpha6beta4 integrin and the 180-kD bullous pemphigoid antigen/type XVII collagen genes. Exp Dermatol 1998; 7:46-64. [PMID: 9583744 DOI: 10.1111/j.1600-0625.1998.tb00304.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Epidermolysis bullosa (EB), a heterogeneous group of genodermatoses, is characterized by fragility and blistering of the skin, associated with characteristic extracutaneous manifestations. Based on clinical severity, constellation of the phenotypic manifestations, and the level of tissue separation within the cutaneous basement membrane zone, EB has been divided into distinct subcategories. Traditionally, these include the simplex, junctional and dystrophic variants of EB. Recent attention has been drawn to variants of EB demonstrating tissue separation at the level of hemidesmosomes, ultrastructurally recognizable adhesion complexes within the cutaneous basement membrane zone. Clinically, these hemidesmosomal variants manifest either as generalized atrophic benign epidermolysis bullosa (GABEB), EB with pyloric atresia, or EB with late-onset muscular dystrophy. Elucidation of basement membrane zone components by molecular cloning and development of mutation detection strategies have revealed that the hemidesmosomal variants of EB result from mutations in the genes encoding the subunit polypeptides of the 180-kD bullous pemphigoid antigen/type XVII collagen, the alpha6beta4 integrin, or plectin, respectively. Collectively, these data add to the understanding of the molecular complexity of the cutaneous basement membrane zone in EB, as attested by the fact that mutations in 10 different genes can underlie different variants of EB. Elucidation of mutations in different forms of EB has direct application to genetic counseling and DNA-based prenatal testing in families with EB.
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Affiliation(s)
- L Pulkkinen
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
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166
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Abstract
Considerable progress has been made recently in elucidating the molecular pathology underlying several forms of inherited skin diseases. One of the most immediate benefits of these discoveries has been the development of DNA-based prenatal diagnosis in pregnancies at risk for recurrence of a particular disorder. In less than 2 decades, prenatal testing has progressed from mid-trimester fetal skin biopsies or protein analysis in a limited number of conditions to first trimester chorionic villus sampling in a much broader range of genodermatoses. Advances in in vitro fertilization protocols and embryo manipulation technology have further led to the feasibility of even earlier prenatal diagnosis through preimplantation genetic diagnosis. This article details some of the recent advances in genetic skin disease research relevant to prenatal diagnosis and explores the possibilities and practicalities of preimplantation genetic diagnosis in the prevention of these conditions.
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Affiliation(s)
- J A McGrath
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, London, UK
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167
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Arbiser JL, Fine JD, Murrell D, Paller A, Connors S, Keough K, Marsh E, Folkman J. Basic Fibroblast Growth Factor: A Missing Link between Collagen VII, Increased Collagenase, and Squamous Cell Carcinoma in Recessive Dystrophic Epidermolysis Bullosa. Mol Med 1998. [DOI: 10.1007/bf03401916] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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168
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Posteraro P, Sorvillo S, Gagnoux-Palacios L, Angelo C, Paradisi M, Meneguzzi G, Castiglia D, Zambruno G. Compound heterozygosity for an out-of-frame deletion and a splice site mutation in the LAMB3 gene causes nonlethal junctional epidermolysis bullosa. Biochem Biophys Res Commun 1998; 243:758-64. [PMID: 9501007 DOI: 10.1006/bbrc.1998.8180] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Laminin-5 is the major adhesion ligand of epithelial cells. Mutations in the genes encoding laminin-5 cause junctional epidermolysis bullosa (JEB), a clinically and genetically heterogeneous group of recessively inherited blistering disease of skin and mucous membranes. In this report, we describe a patient with a non-lethal variant of JEB who is a compound heterozygous for mutations affecting the LAMB3 gene. The paternally inherited mutation is a deletion of a single base (T) leading to a frameshift and premature termination codon. It results in mRNA decay. The maternally inherited mutation is a G-->A transition at the last base of exon 7 (628G-->A) which converts a codon for glutamic acid in a codon for lysine (E210K). The mutation 628G-->A alters the correct splicing of LAMB3 pre-mRNA giving rise to two aberrant mRNA, in addition to the RNA transcript carrying the G-->A substitution. This result is compatible with the reduced expression of mutated laminin 5 molecules with altered biological activity, and the mild JEB phenotype observed in the patient.
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Affiliation(s)
- P Posteraro
- Laboratory of Molecular & Cell Biology, Istituto Dermopatico dell'Immacolata, IRCCS, Rome, Italy
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169
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Yoshiba K, Yoshiba N, Aberdam D, Meneguzzi G, Perrin-Schmitt F, Stoetzel C, Ruch JV, Lesot H. Expression and localization of laminin-5 subunits during mouse tooth development. Dev Dyn 1998; 211:164-76. [PMID: 9489770 DOI: 10.1002/(sici)1097-0177(199802)211:2<164::aid-aja5>3.0.co;2-f] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Tooth morphogenesis is regulated by epithelial-mesenchymal interactions mediated by the basement membrane (BM). Laminins are major glycoprotein components of the BMs, which are involved in several cellular activities. The expression and localization of the alpha3, beta3, and gamma2 laminin-5 subunits have been analyzed by in situ hybridization and immunohistochemistry during mouse molar development. Initially (E12), mRNAs of all subunits were detected in the entire dental epithelium and the corresponding proteins were located in the BM. During cap formation (E13-14), transcripts for the alpha3 and gamma2 subunits were localized in the outer dental epithelium (ODE), whereas the beta3 subunit mRNA was present in the inner dental epithelium (IDE). During the early bell stage (E16), immunoreactivity for all subunits disappeared from the BM along the IDE, although intense signals for beta3 mRNA were detectable in cells of the IDE. Subsequently, when the dentinal matrix was secreted by odontoblasts (E18-19.5), mRNAs of all three subunits were re-expressed by ameloblasts, and the corresponding proteins were detected in ameloblasts and in the enamel matrix. Tissue recombination experiments demonstrated that when E16 IDE or ODE was associated with E18 dental papilla mesenchyme, immunostaining for all laminin-5 subunits disappeared from the BM, whereas when cultured with non-dental limb bud mesenchyme, they remained positive after 48 hr of culture. These results suggest that the temporospatial expression of laminin-5 subunits in tooth development, which appears to be differentially controlled by the dental mesenchyme, might be related to the enamel organ histo-morphogenesis and the ameloblast differentiation.
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Affiliation(s)
- K Yoshiba
- INSERM U424, Institut de Biologie Médicale, Faculté de Médicine, Strasbourg, France.
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170
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Lapinski P, Lapiere JC, Traczyk T, Chan LS. Sporadic dystrophic epidermolysis bullosa with concomitant atopic dermatitis. Br J Dermatol 1998; 138:315-20. [PMID: 9602882 DOI: 10.1046/j.1365-2133.1998.02082.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We describe a patient with sporadic dystrophic epidermolysis bullosa associated with well-documented atopic dermatitis. We discuss this case in relation to a newly described clinical subtype of epidermolysis bullosa known as epidermolysis bullosa pruriginosa, a dystrophic variant associated with prominent pruritus. The relations of this case of sporadic dystrophic epidermolysis bullosa with other dominantly inherited forms of dystrophic epidermolysis bullosa such as the Pasini variant, the pretibial variant, and Bart's syndrome are also discussed. The role of atopic dermatitis in exacerbating dystrophic epidermolysis bullosa in this patient raises an important consideration in the care of this group of patients.
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Affiliation(s)
- P Lapinski
- Department of Dermatology, Northwestern University Medical School, Chicago, IL 60611, USA
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171
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MELLERIO J, SMITH F, McMILLAN J, McLEAN W, McGRATH J, MORRISON G, TIERNEY P, ALBERT D, WICHE G, LEIGH I, GEDDES J, LANE E, UITTO J, EADY R. Recessive epidermolysis bullosa simplex associated with plectin mutations: infantile respiratory complications in two unrelated cases. Br J Dermatol 1997. [DOI: 10.1111/j.1365-2133.1997.tb01549.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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172
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Christiano AM, Fine JD, Uitto J. Genetic basis of dominantly inherited transient bullous dermolysis of the newborn: a splice site mutation in the type VII collagen gene. J Invest Dermatol 1997; 109:811-4. [PMID: 9406826 DOI: 10.1111/1523-1747.ep12341013] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Transient bullous dermolysis of the newborn (TBDN) is a blistering disease evident at birth or shortly thereafter, but the blistering tendency decreases with advancing age. The tissue separation in TBDN is below the lamina densa, and electron microscopy has revealed abnormalities in anchoring fibrils. Immunofluorescence staining demonstrates intracellular accumulation of type VII collagen. In this study, we report a G-to-C transversion mutation in the last nucleotide of intron 35 of the type VII collagen gene (COL7A1) in a family with autosomal dominant TBDN in three generations. This nucleotide substitution abolishes the obligatory consensus 3'-acceptor splice site, predicting in-frame skipping of exon 36. Thus, TBDN in this family is caused by a mutation in COL7A1, and is therefore allelic with other variants of dominant dystrophic epidermolysis bullosa.
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Affiliation(s)
- A M Christiano
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107-5541, USA
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173
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Cserhalmi-Friedman PB, Karpati S, Horvath A, Christiano AM. Identification of the glycine-to-arginine substitution G2043R in type VII collagen in a family with dominant dystrophic epidermolysis bullosa from Hungary. Exp Dermatol 1997; 6:303-7. [PMID: 9412818 DOI: 10.1111/j.1600-0625.1997.tb00177.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Epidermolysis bullosa (EB) represents a group of genodermatoses characterized by fragility and easy blistering of the skin. In the dystrophic forms of EB (DEB), blisters occur below the basement membrane, at the level of the anchoring fibrils. In the dominantly inherited forms (DDEB), the predominant type of mutation detected thus far is the substitution of a glycine residue which occurs within the collagenous domain of the molecule characterized by the repeating Gly-X-Y amino acid sequence. In this study, we searched for mutations in DDEB in a family from Hungary, by PCR amplification of segments of COL7A1, followed by heteroduplex analysis. Examination of the PCR fragment corresponding to exon 73 revealed a heteroduplex in affected individuals from the family. Sequence analysis revealed a G-to-A transition at nucleotide 6127 in the triple-helical domain of COL7A1, which converted a glycine residue at amino acid position 2043 to an arginine. This report represents the second incidence of this mutation, G2043R, described first in a family with DDEB from Italy.
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Affiliation(s)
- P B Cserhalmi-Friedman
- Department of Dermatology, College of Physicians & Surgeons, Columbia University, New York, NY 10032, USA
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174
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Kon A, Nomura K, Pulkkinen L, Sawamura D, Hashimoto I, Uitto J. Novel glycine substitution mutations in COL7A1 reveal that the Pasini and Cockayne-Touraine variants of dominant dystrophic epidermolysis bullosa are allelic. J Invest Dermatol 1997; 109:684-7. [PMID: 9347800 DOI: 10.1111/1523-1747.ep12338093] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Mutations in the type VII collagen gene (COL7A1) have been shown to underlie dystrophic epidermolysis bullosa (DEB). The dominantly inherited forms of DEB have been divided into two clinical subcategories, the Pasini (DDEB-P) and the Cockayne-Touraine (DDEB-CT) variants, on the basis of the presence or absence of albopapuloid lesions. In this study, we have examined the molecular basis of DDEB in two Japanese families, one with DDEB-P and the other with DDEB-CT. Mutation detection strategy consisted of polymerase chain reaction amplification of COL7A1 from genomic DNA, followed by heteroduplex analysis and direct nucleotide sequencing. The results revealed heterozygous glycine substitution mutations, G2076D and G2034R, in these families, respectively. Thus, these two variants of DDEB are allelic, and subtle differences in the clinical presentation may reflect the precise position of the mutation along the type VII collagen molecule. Alternatively, the nature of the substituting amino acid (D versus R) may influence the clinical phenotype. This is the first demonstration of a COL7A1 mutation in DDEB-P, and brings the total number of dominant DEB variants with underlying glycine substitutions in COL7A1 to five, including the pretibial and localized variants as well as the Bart's syndrome, in addition to DDEB-P and DDEB-CT.
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Affiliation(s)
- A Kon
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Philadelphia, PA 19107, USA
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175
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Abstract
Spectacular success has recently been made in understanding the molecular basis of various heritable skin diseases. A prototype of such conditions is epidermolysis bullosa (EB), a heterogenous group of mechano-bullous disorders, characterized by fragility of the skin and other specialized epithelia. The fragility of the skin in EB results from defective attachment of the epidermis to the underlying dermis due to genetic lesions within molecules of the basement membrane zone (BMZ) at the dermal-epidermal junction. Specifically, distinct mutations have been disclosed thus far in ten different genes encoding the macromolecular components of the BMZ, and the combinations and the types of mutations as well as their positions along the altered gene products collectively reflect the phenotypic variability observed in this group of heritable skin diseases. This information has major implications for genetic counseling of families at risk for recurrence of EB in subsequent pregnancies and in future generations. Furthermore, examination of specific mutations in an affected newborn allows prognostication of the severity of the clinical outcome. Finally, mutation analyses have provided the basis to develop DNA-based prenatal testing by chorionic villus sampling or early aminocentesis during the first trimester of gestation. Collectively, the advances on EB exemplify the potential of molecular biology for improved diagnosis and patient care of genetic skin disorders.
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Affiliation(s)
- J Uitto
- Department of Dermatology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
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176
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Uitto J, Pulkkinen L, McLean WH. Epidermolysis bullosa: a spectrum of clinical phenotypes explained by molecular heterogeneity. MOLECULAR MEDICINE TODAY 1997; 3:457-65. [PMID: 9358473 DOI: 10.1016/s1357-4310(97)01112-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Great progress has recently been made in understanding the molecular basis of various heritable skin diseases. A prototype of such conditions is epidermolysis bullosa (EB), a heterogeneous group of mechano-bullous disorders characterized by fragility of the skin and other specialized epithelia. Blistering of the skin in EB results either from fragility of epidermal cells or from defective attachment of the epidermis to the underlying dermis, because of genetic lesions within molecules of the basement-membrane zone at the dermal-epidermal junction. Distinct mutations have been discovered in ten different genes encoding the structural components within this layer. The combinations and the types of mutations, as well as their positions in the altered gene products, collectively reflect the phenotypic variability observed in this group of heritable skin diseases.
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Affiliation(s)
- J Uitto
- Jefferson Medical College, Dept of Dermatology and Cutaneous Biology, Philadelphia, PA 19107, USA.
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177
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Marinkovich MP, Tran HH, Rao SK, Giudice GJ, Balding S, Jonkman MF, Pas HH, McGuire JS, Herron GS, Bruckner-Tuderman L. LAD-1 is absent in a subset of junctional epidermolysis bullosa patients. J Invest Dermatol 1997; 109:356-9. [PMID: 9284104 DOI: 10.1111/1523-1747.ep12336033] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The anchoring filament protein LAD-1 has been recently identified as the target of autoantibodies in the acquired blistering disorder linear IgA bullous dermatosis. Because this protein appears to be involved in the process of dermal-epidermal cohesion, this study sought to determine the involvement of LAD-1 in the pathology of junctional epidermolysis bullosa (JEB). To this end, 44 patients with a variety of subtypes of JEB were analyzed by indirect immunofluorescence microscopy with antibodies to LAD-1, BP180, and laminin-5. We found that only patients with generalized atrophic benign epidermolysis bullosa (GABEB) contained LAD-1 defects. Of the 16 GABEB patients studied, 13 showed absent or greatly reduced expression of LAD-1 (including 2 patients with a peculiar interrupted staining pattern) and 3 patients showed defects of laminin-5 expression with normal LAD-1 expression. Patients who showed LAD-1 defects also showed abnormal expression of BP180. Keratinocytes were cultured from the skin of two GABEB patients and analyzed by indirect immunofluorescent microscopy. One culture demonstrated defects of BP180 and LAD-1 expression (which was also verified by radioimmunoprecipitation assay), and one culture showed decreased laminin-5 expression but normal BP180 and LAD-1 expression. Thus, these studies demonstrate that: (i) LAD-1 and BP180 are normally expressed in all subtypes of JEB except GABEB, (ii) the majority of GABEB patients show absent or near absent expression of both LAD-1 and BP180 but normal expression of laminin-5, and (iii) a smaller subset of GABEB patients show normal LAD-1 and BP180 expression but express persistent but reduced levels of laminin-5.
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Affiliation(s)
- M P Marinkovich
- Veterans Administration Palo Alto Health Care System, and Department of Dermatology at Stanford University School of Medicine, California 94305, U.S.A
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178
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Kuster JE, Guarnieri MH, Ault JG, Flaherty L, Swiatek PJ. IAP insertion in the murine LamB3 gene results in junctional epidermolysis bullosa. Mamm Genome 1997; 8:673-81. [PMID: 9271670 DOI: 10.1007/s003359900535] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The laminin-5 molecule functions in the attachment of various epithelia to basement membranes. Mutations in the laminin-5-coding genes have been associated with Herlitz junctional epidermolysis bullosa (HJEB), a severe and often lethal blistering disease of humans. Here we report the characterization of a spontaneous mouse mutant with an autosomal recessive blistering disease. These mice exhibit sub-epithelial blisters of the skin and mucosal surfaces and abnormal hemidesmosomes lacking sub-basal dense plates. By linkage analysis the genetic defect was localized to a 2-cM region on distal Chromosome (Chr) 1 where a laminin-5 subunit gene, LamB3, was previously localized. LamB3 mRNA and laminin-5 protein were undetectable by Northern blot analysis and immunohistochemical methods, respectively. DNA sequence analysis indicated that the LamB3 genetic defect resulted from disruption of the coding sequence by insertion of an intracisternal-A particle (IAP) at an exon/intron junction. These findings suggest a role for laminin-5 in hemidesmosome formation and indicate that the LamB3(IAP) mutant is a useful mouse model for HJEB.
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Affiliation(s)
- J E Kuster
- Division of Genetic Disorders, Laboratory of Developmental Genetics, Wadsworth Center, New York State Department of Health, P.O. Box 22002, Albany, New York 12201-2002, USA
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179
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Hammami-Hauasli N, Kalinke DU, Schumann H, Kalinke U, Pontz BF, Anton-Lamprecht I, Pulkkinen L, Zimmermann M, Uitto J, Bruckner-Tuderman L. A combination of a common splice site mutation and a frameshift mutation in the COL7A1 gene: absence of functional collagen VII in keratinocytes and skin. J Invest Dermatol 1997; 109:384-9. [PMID: 9284109 DOI: 10.1111/1523-1747.ep12336264] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We describe a patient with severe generalized dystrophic epidermolysis bullosa (EBD) and a novel combination of compound heterozygous mutations in the COL7A1 gene. The maternal mutation was an A-to-G transition (425-A --> G) at position -2 of the donor splice site within exon 3 that causes aberrant splicing of two abnormal transcripts. One includes intron 3, and one excludes both exon 3 and intron 3. Both splice variants contained a premature termination of the translation. The paternal mutation is a 25-bp deletion in exon 20 (2638de125) that leads to a frameshift and a premature termination codon 133 bp downstream from the site of deletion. This combination of mutations allowed expression of collagen VII mRNA. Immunofluorescence staining of the patient's skin and cultured keratinocytes with domain-specific collagen VII antibodies, however, demonstrated markedly reduced levels of alpha1(VII) polypeptides, and no stable collagen VII protein could be extracted from the patient's cells. Electron microscopy showed severely hypoplastic fibrils below the lamina densa, without evidence of normal anchoring fibrils. The clinically unaffected parents were heterozygous for the mutations, suggesting that both COL7A1 gene defects were recessively inherited disease-causing mutations that are "silent" in heterozygous carriers but in combination can severely interfere with the dermal-epidermal adhesion and lead to severe EBD.
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180
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181
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Puvabanditsin S, Garrow E, Samransamraujkit R, Lopez LA, Lambert WC. Epidermolysis bullosa associated with congenital localized absence of skin, fetal abdominal mass, and pyloric atresia. Pediatr Dermatol 1997; 14:359-62. [PMID: 9336805 DOI: 10.1111/j.1525-1470.1997.tb00981.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A 2320-g male infant was delivered at 35 weeks gestation to a mother who had polyhydramnios. He had a combination of congenital localized absence of skin, unilateral hydronephrosis, and hydroureter due to ureterovesical obstruction, and nonbilious vomiting due to pyloric atresia. Blistering of the skin developed after birth. Epidermolysis bullosa simplex was confirmed by electron microscopy of a skin biopsy specimen. We describe this patient, who had three unusual manifestations of epidermolysis bullosa.
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Affiliation(s)
- S Puvabanditsin
- Department of Pediatrics, University of Medicine and Dentistry of New Jersey, Newark, USA
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182
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Hu ZL, Smith L, Martins S, Bonifas JM, Chen H, Epstein EH. Partial dominance of a keratin 14 mutation in epidermolysis bullosa simplex--increased severity of disease in a homozygote. J Invest Dermatol 1997; 109:360-4. [PMID: 9284105 DOI: 10.1111/1523-1747.ep12336051] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Epidermolysis bullosa simplex is a disease in which keratin gene mutations cause the production of defective intermediate filaments, which leads in turn to epidermal basal cell fragility and blistering. The inheritance in nearly all kindreds is autosomal dominant, most kindreds have missense mutations, and the encoded proteins appear to exert a dominant negative function. One previously reported patient with generalized blistering had a fully dominant mutation of keratin 5; in that kindred a homozygote was affected no more severely than the heterozygotes. By contrast we report here a keratin 14 mutation that causes blistering limited to the hands and feet in heterozygotes, but homozygotes have more severe, widespread blistering of the skin and mucous membranes. Thus keratin gene mutations may be not only fully recessive or fully dominant but also partially dominant as well.
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Affiliation(s)
- Z L Hu
- Department of Dermatology, University of California San Francisco, U.S.A
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183
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Hovnanian A, Rochat A, Bodemer C, Petit E, Rivers CA, Prost C, Fraitag S, Christiano AM, Uitto J, Lathrop M, Barrandon Y, de Prost Y. Characterization of 18 new mutations in COL7A1 in recessive dystrophic epidermolysis bullosa provides evidence for distinct molecular mechanisms underlying defective anchoring fibril formation. Am J Hum Genet 1997; 61:599-610. [PMID: 9326325 PMCID: PMC1715975 DOI: 10.1086/515495] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We have characterized 21 mutations in the type VII collagen gene (COL7A1) encoding the anchoring fibrils, 18 of which were not previously reported, in patients from 15 unrelated families with recessive dystrophic epidermolysis bullosa (RDEB). COL7A1 mutations in both alleles were identified by screening the 118 exons of COL7A1 and flanking intron regions. Fourteen mutations created premature termination codons (PTCs) and consisted of nonsense mutations, small insertions, deletions, and splice-site mutations. A further seven mutations predicted glycine or arginine substitutions in the collagenous domain of the molecule. Two mutations were found in more than one family reported in this study, and six of the seven missense mutations showed clustering within exons 72-74 next to the hinge region of the protein. Patients who were homozygous or compound heterozygotes for mutations leading to PTCs displayed both absence or drastic reduction of COL7A1 transcripts and undetectable type VII collagen protein in skin. In contrast, missense mutations were associated with clearly detectable COL7A1 transcripts and with normal or reduced expression of type VII collagen protein at the dermo/epidermal junction. Our results provide evidence for at least two distinct molecular mechanisms underlying defective anchoring fibril formation in RDEB: one involving PTCs leading to mRNA instability and absence of protein synthesis, the other implicating missense mutations resulting in the synthesis of type VII collagen polypeptide with decreased stability and/or altered function. Genotype-phenotype correlations suggested that the nature and location of these mutations are important determinants of the disease phenotype and showed evidence for interfamilial phenotypic variability.
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Affiliation(s)
- A Hovnanian
- The Wellcome Trust Centre for Human Genetics, University of Oxford, United Kingdom.
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184
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185
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Ferrigno O, Virolle T, Galliano MF, Chauvin N, Ortonne JP, Meneguzzi G, Aberdam D. Murine laminin alpha3A and alpha3B isoform chains are generated by usage of two promoters and alternative splicing. J Biol Chem 1997; 272:20502-7. [PMID: 9252362 DOI: 10.1074/jbc.272.33.20502] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We already identified two distinct laminin alpha3A and alpha3B chain isoforms which differ in their amino-terminal ends and display different tissue-specific expression patterns. In this study we have investigated whether these two different isoforms are products of the same laminin alpha3 (lama3) gene and transcribed from one or two separate promoters. Genomic clones were isolated that encompass the sequences upstream to the 5' ends of both the alpha3A and the alpha3B cDNAs. Sequence analysis of the region upstream to the alpha3A open reading frame revealed the presence of a TATA box and potential binding sites for responsive elements. By primer extension analysis, the transcription start site of the alpha3B mRNA isoform was defined. The sequences upstream to the alpha3B mRNA transcription start site do not contain a TATA box near the transcription initiation sites, but AP-1, AP-2, and Sp1 consensus binding site sequences were identified. The genomic regions located immediately upstream of the alpha3A and alpha3B transcription start sites were shown to possess promoter activities in transfection experiments. In the promoter regions, response elements for the acute phase reactant signal and NF-interleukin 6 were found, and their possible relevance in the context of inflammation and wound healing is discussed. Our results demonstrate that the lama3 gene produces the two polypeptides by alternative splicing and contains two promoters, which regulate the production of the two isoforms alpha3A and alpha3B.
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Affiliation(s)
- O Ferrigno
- U385 INSERM, Faculté de Médecine, 06107 Nice Cedex 2, France
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186
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Pulkkinen L, Meneguzzi G, McGrath JA, Xu Y, Blanchet-Bardon C, Ortonne JP, Christiano AM, Uitto J. Predominance of the recurrent mutation R635X in the LAMB3 gene in European patients with Herlitz junctional epidermolysis bullosa has implications for mutation detection strategy. J Invest Dermatol 1997; 109:232-7. [PMID: 9242513 DOI: 10.1111/1523-1747.ep12319752] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Junctional forms of epidermolysis bullosa (JEB) are characterized by tissue separation at the level of the lamina lucida. We have recently disclosed specific mutations in the LAMA3, LAMB3, and LAMC2 genes encoding the subunit polypeptides of the anchoring filament protein laminin 5 in 66 families with different variants of JEB. Examination of the JEB mutation database revealed recurrence of a particular C-->T substitution at nucleotide position 1903 (exon 14) of LAMB3, resulting in the mutation R635X. The inheritance of this nonsense mutation was noted on different genetic backgrounds, suggesting that R635X is a hotspot mutation. In this study, we have performed mutation evaluation in a European cohort of 14 families with the lethal, Herlitz type of JEB (H-JEB). The families were first screened for the presence of the R635X mutation by restriction enzyme digestion of the PCR product corresponding to exon 14. Four of the probands were found to be homozygous and six were heterozygous for R635X. The remaining alleles were subjected to mutation screening by PCR amplification of individual exons of LAMB3 and LAMC2, followed by heteroduplex analysis and nucleotide sequencing. In three families (six alleles), mutations in LAMC2 were disclosed. In the remaining eight alleles, additional pathogenetic LAMB3 mutations were found. None of the patients had LAMA3 mutation. Thus, LAMB3 mutations accounted for 22 of 28 JEB alleles (79%), and a total of 14 of 22 LAMB3 alleles (64%) harbored the R635X mutation, signifying its prevalence as a predominant genetic lesion underlying H-JEB in this European cohort of patients. This recurrent mutation will facilitate screening of additional JEB patients for the purpose of prenatal testing of fetuses at risk for recurrence.
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Affiliation(s)
- L Pulkkinen
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, U.S.A
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187
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Basarab T, Dunnill MG, Eady RA, Russell-Jones R. Herlitz junctional epidermolysis bullosa: a case report and review of current diagnostic methods. Pediatr Dermatol 1997; 14:307-11. [PMID: 9263316 DOI: 10.1111/j.1525-1470.1997.tb00965.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We report an infant with Herlitz junctional epidermolysis bullosa (JEB) presenting at birth with erosions on the scalp, thigh and periumbilical area in addition to nail abnormalities. Ultrastructural studies demonstrated a split through the lamina lucida with poorly formed hemidesmosomes and no clearly defined subbasal dense plates. Indirect immunofluorescence staining with antibodies GB3 (antilaminin 5) and 19-DEJ-1 (antiuncein) was totally absent. These findings, in combination with the clinical picture, favor a diagnosis of Herlitz JEB. Immunohistochemistry findings greatly facilitated an accurate diagnosis, which is essential in view of the poor prognosis for patients with this form of junctional epidermolysis bullosa.
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Affiliation(s)
- T Basarab
- Department of Dermatology, Ealing Hospital NHS Trust, Middlesex, England
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188
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Chavanas S, Gache Y, Tadini G, Pulkkinen L, Uitto J, Ortonne JP, Meneguzzi G. A homozygous in-frame deletion in the collagenous domain of bullous pemphigoid antigen BP180 (type XVII collagen) causes generalized atrophic benign epidermolysis bullosa. J Invest Dermatol 1997; 109:74-8. [PMID: 9204958 DOI: 10.1111/1523-1747.ep12276614] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We report a missplicing event affecting the expression of bullous pemphigoid antigen BP180 (type XVII collagen) in a patient with generalized atrophic benign epidermolysis bullosa (GABEB). The segregation of the mutated allele in the family is consistent with the pathogenic role of the mutation. The homozygous mutation 2441-2A --> G disrupts a splice-site sequence in gene (BPAG2) for BP180 and results in an in-frame exon skipping within the collagenous ectodomain of the protein. The consequent deletion of 9 amino acids in the mutant BP180 is predicted to alter the structure of the homotrimer and is expected to exert a deleterious effect on stability of the protein that would account for the complete absence of immunoreactivity of the proband's skin to antibodies directed against BP180. These findings underscore the importance of structural integrity of the extracellular domain of BP180 for the stability of the protein.
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Affiliation(s)
- S Chavanas
- U385 Institut National de la Santé et de la Recherche Médicale, Faculté de Médecine, Nice, France
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189
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O'Toole EA, Marinkovich MP, Hoeffler WK, Furthmayr H, Woodley DT. Laminin-5 inhibits human keratinocyte migration. Exp Cell Res 1997; 233:330-9. [PMID: 9194495 DOI: 10.1006/excr.1997.3586] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Laminin-5 (previously known as kalinin, epiligrin, and nicein) is an adhesive protein localized to the anchoring filaments within the lamina lucida space of the basement membrane zone lying between the epidermis and dermis of human skin. Anchoring filaments are structures within the lamina lucida and lie immediately beneath the hemidesmosomes of the overlying basal keratinocytes apposed to the basement membrane zone. Human keratinocytes synthesize and deposit laminin-5. Laminin-5 is present at the wound edge during reepithelialization. In this study, we demonstrate that laminin-5, a powerful matrix attachment factor for keratinocytes, inhibits human keratinocyte migration. We found that the inhibitory effect of laminin-5 on keratinocyte motility can be reversed by blocking the alpha3 integrin receptor. Laminin-5 inhibits keratinocyte motility driven by a collagen matrix in a concentration-dependent fashion. Using antisense oligonucleotides to the alpha3 chain of laminin-5 and an antibody that inhibits the cell binding function of secreted laminin-5, we demonstrated that the endogenous laminin-5 secreted by the keratinocyte also inhibits the keratinocyte's own migration on matrix. These findings explain the hypermotility that characterizes keratinocytes from patients who have forms of junctional epidermolysis bullosa associated with defects in one of the genes encoding for laminin-5 chains, resulting in low expression and/or functional inadequacy of laminin-5 in these patients. These studies also suggest that during reepithelialization of human skin wounds, the secreted laminin-5 stabilizes the migrating keratinocyte to establish the new basement membrane zone.
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Affiliation(s)
- E A O'Toole
- Department of Dermatology, Northwestern University, Chicago, Illinois 60611, USA
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190
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Ruzzi L, Gagnoux-Palacios L, Pinola M, Belli S, Meneguzzi G, D'Alessio M, Zambruno G. A homozygous mutation in the integrin alpha6 gene in junctional epidermolysis bullosa with pyloric atresia. J Clin Invest 1997; 99:2826-31. [PMID: 9185503 PMCID: PMC508131 DOI: 10.1172/jci119474] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The alpha6 integrin subunit participates in the formation of both alpha6beta1 and alpha6beta4 laminin receptors, which have been reported to play an important role in cell adhesion and migration and in morphogenesis. In squamous epithelia, the alpha6beta4 heterodimer is the crucial component for the assembly and stability of hemidesmosomes. These anchoring structures are ultrastructurally abnormal in patients affected with junctional epidermolysis bullosa with pyloric atresia (PA-JEB), a recessively inherited blistering disease of skin and mucosae characterized by an altered immunoreactivity with antibodies specific to integrin alpha6beta4. In this report, we describe the first mutation in the alpha6 integrin gene in a PA-JEB patient presenting with generalized skin blistering, aplasia cutis, and defective expression of integrin alpha6beta4. The mutation (791delC) is a homozygous deletion of a single base (C) leading to a frameshift and a premature termination codon that results in a complete absence of alpha6 polypeptide. We also describe the DNA-based prenatal exclusion of the disease in this family at risk for recurrence of PA-JEB. Our results demonstrate that, despite the widespread distribution of the alpha6 integrin subunit, lack of expression of the alpha6 integrin chain is compatible with fetal development, and results in a phenotype indistinguishable from that caused by mutations in the beta4 chain, which is expressed in a more limited number of tissues.
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Affiliation(s)
- L Ruzzi
- Laboratory of Molecular and Cell Biology, Istituto Dermopatico dell'Immacolata, IRCCS, 00167 Rome, Italy
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191
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Lee JY, Pulkkinen L, Liu HS, Chen YF, Uitto J. A glycine-to-arginine substitution in the triple-helical domain of type VII collagen in a family with dominant dystrophic epidermolysis bullosa pruriginosa. J Invest Dermatol 1997; 108:947-9. [PMID: 9182828 DOI: 10.1111/1523-1747.ep12296242] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Epidermolysis bullosa pruriginosa is a recently recognized variant of dystrophic epidermolysis bullosa (DEB) characterized by severe pruritus and scarring, mainly involving the extensors of the extremities. In this study, we searched for mutations in the type VII collagen gene (COL7A1) using polymerase chain reaction amplification of exonic segments of COL7A1, followed by heteroduplex analysis, in a Chinese pedigree with dominant DEB displaying a striking anastomosing network of lichenoid papules and scarring. The study revealed a G-to-A transition at nucleotide 6724 within exon 85 of COL7A1, converting a glycine to an arginine (G2242R) within the triple-helical domain of the type VII collagen in affected individuals. These findings demonstrate that EB pruriginosa in this family is a clinical variant of dominant DEB.
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Affiliation(s)
- J Y Lee
- Department of Dermatology, National Cheng Kung University Hospital, Tainan, Taiwan, R.O.C
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192
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MCMILLAN J, MCGRATH J, PULKKINEN L, KON A, BURGESON R, ORTONNE JP, MENEGUZZI G, UITTO J, EADY R. Immunohistochemical analysis of the skin in junctional epidermolysis bullosa using laminin 5 chain specific antibodies is of limited value in predicting the underlying gene mutation. Br J Dermatol 1997. [DOI: 10.1111/j.1365-2133.1997.tb03918.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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193
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Takizawa Y, Shimizu H, Nishikawa T, Hatta N, Pulkkinen L, Uitto J. Novel ITGB4 mutations in a patient with junctional epidermolysis bullosa-pyloric atresia syndrome and altered basement membrane zone immunofluorescence for the alpha6beta4 integrin. J Invest Dermatol 1997; 108:943-6. [PMID: 9182827 DOI: 10.1111/1523-1747.ep12296240] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Immunofluorescence studies of junctional epidermolysis bullosa with pyloric atresia (JEB-PA) have suggested abnormalities in the expression of the alpha6 beta4 integrin, an integral component of hemidesmosomes. In this study, we examined a family with two affected individuals with JEB-PA for mutations in the ITGA6 and ITGB4 genes which encode the alpha6 and beta4 integrin polypeptides, respectively. Mutation detection strategy based on PCR amplification of genomic DNA, followed by heteroduplex analysis and direct nucleotide sequencing, did not reveal sequence variants in ITGA6. Putative pathogenic mutations, however, were identified in both ITGB4 alleles. Specifically, the proband was a compound heterozygote for a 1-bp maternal deletion, 3434delT, and an 8-bp paternal deletion, 4050de18. Both mutations result in a frameshift and premature termination codon downstream from the deletion. At the protein level, immunofluorescence of the skin of the proband revealed negative staining for the integrin alpha6 and markedly reduced staining for the beta4 subunit. Thus, the results support the notion of close association of the alpha6 beta4 integrin subunits and further attest to the critical role of this integrin in providing physiologic stability to the dermal-epidermal junction.
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MESH Headings
- Alleles
- Antibodies, Monoclonal/analysis
- Antibodies, Monoclonal/immunology
- Antigens, CD/analysis
- Antigens, CD/genetics
- Antigens, CD/immunology
- Antigens, Surface/analysis
- Antigens, Surface/genetics
- Antigens, Surface/immunology
- Base Sequence
- Basement Membrane/chemistry
- Basement Membrane/immunology
- Basement Membrane/ultrastructure
- DNA/analysis
- DNA/chemistry
- DNA/genetics
- Desmosomes/chemistry
- Desmosomes/ultrastructure
- Epidermolysis Bullosa, Junctional/genetics
- Epidermolysis Bullosa, Junctional/pathology
- Exons
- Female
- Gene Deletion
- Heterozygote
- Humans
- Immunohistochemistry
- Infant, Newborn
- Integrin alpha6
- Integrin alpha6beta4
- Integrin beta4
- Integrins/analysis
- Integrins/genetics
- Integrins/immunology
- Male
- Mutation
- Polymerase Chain Reaction
- Pylorus/abnormalities
- Skin/chemistry
- Skin/pathology
- Skin/ultrastructure
- Syndrome
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Affiliation(s)
- Y Takizawa
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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194
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ASHTON G, MELLERIO J, DUNNILL M, PULKKINEN L, CHRISTIANO A, UITTO J, EADY R, McGRATH J. A recurrent laminin 5 mutation in British patients with lethal (Herlitz) junctional epidermolysis bullosa: evidence for a mutational hotspot rather than propagation of an ancestral allele. Br J Dermatol 1997. [DOI: 10.1111/j.1365-2133.1997.tb03650.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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195
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Pulkkinen L, Kimonis VE, Xu Y, Spanou EN, McLean WH, Uitto J. Homozygous alpha6 integrin mutation in junctional epidermolysis bullosa with congenital duodenal atresia. Hum Mol Genet 1997; 6:669-74. [PMID: 9158140 DOI: 10.1093/hmg/6.5.669] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Junctional epidermolysis bullosa with congenital pyloric or duodenal atresia is a distinct variant within this group of autosomal recessive blistering skin diseases. In this study we demonstrate, for the first time, a homozygous mutation in the alpha6 integrin gene (ITGA6) in a family with three affected individuals. For this purpose, we first determined the genomic organization of ITGA6, and placed the gene on chromosome 2q by high resolution radiation hybrid mapping. Heteroduplex analysis of PCR products containing the individual exons of ITGA6, followed by direct nucleotide sequencing, revealed that the proband was homozygous for a G-to-T transversion in the +1 position of intron 12. This mutation, 1856+1G-->T, affects an invariant base of the 5' donor splice site predicting aberrant splicing involving exon 12. The mutation was verified in the proband's DNA by restriction enzyme digestion which also confirmed that the parents were heterozygous carriers of this mutation. Altered expression of alpha6 integrin, which forms a heterodimer with the beta4 subunit at the dermal-epidermal junction, would explain fragility and blistering as a result of minor trauma to the skin.
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Affiliation(s)
- L Pulkkinen
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
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196
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Cserhalmi PB, Horvath A, Boros V, Sapi Z, Kormendi M, Christiano AM, Karpati S. Identification of the LAMB3 hotspot mutation R635X in a Hungarian case of Herlitz junctional epidermolysis bullosa. Exp Dermatol 1997; 6:70-4. [PMID: 9209887 DOI: 10.1111/j.1600-0625.1997.tb00149.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The Herlitz type of junctional epidermolysis bullosa (H-JEB) is a severe blistering disease affecting the skin and mucous membranes, which is usually lethal within the first year of life. The laminin 5 genes have been implicated as candidate genes for most patients with H-JEB. Recently, two hotspot mutations were delineated in the LAMB3 gene, known as R42X and R635X, and have been noted in over 50% of mutant LAMB3 alleles. Here, we present a case of H-JEB of Hungarian origin with a neonatal lethal outcome. Monoclonal antibody staining showed a lack of expression of the laminin 5 beta 3 chain, as a possible result of a mutation in one of the laminin 5 genes. Screening of the family identified the previously described mutation R635X in exon 14 of LAMB3 in each of the parents and one healthy sibling in the heterozygous form, while proband was homozygous for R635X, and the other sibling proved to be genotypically normal. These results underscore the widespread prevalence of R635X in H-JEB cases from around the world.
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Affiliation(s)
- P B Cserhalmi
- Department of Dermatology, Semmelweis Medical University, Budapest, Hungary
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197
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CHRISTIANO ANGELAM, PULKKINEN LEENA, MCGRATH JOHNA, UITTO JOUNI. MUTATION-BASED PRENATAL DIAGNOSIS OF HERLITZ JUNCTIONAL EPIDERMOLYSIS BULLOSA. Prenat Diagn 1997. [DOI: 10.1002/(sici)1097-0223(199704)17:4<343::aid-pd73>3.0.co;2-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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198
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199
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Stephens K, Ehrlich P, Weaver M, Le R, Spencer A, Sybert VP. Primers for exon-specific amplification of the KRT5 gene: identification of novel and recurrent mutations in epidermolysis bullosa simplex patients. J Invest Dermatol 1997; 108:349-53. [PMID: 9036937 DOI: 10.1111/1523-1747.ep12286486] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The KRT5 and KRT14 genes encode the proteins keratin 5 and 14, respectively, which are the primary structural components of the 10-nm intermediate filaments of the mitotic epidermal basal cells. A single mutation in either gene can disrupt the keratin intermediate filament cytoskeleton, resulting in the skin fragility and blistering that is characteristic of the group of inherited disorders known as epidermolysis bullosa simplex. We have established a mutation detection system that facilitates KRT5 gene analysis from leukocyte genomic DNA, obviating the need for a skin sample or keratinocyte culture for cDNA synthesis. KRT5 intronic regions that flanked each exon were sequenced and sets of facing intronic primers were designed for specific amplification of each of the nine KRT5 exons. Direct sequencing of KRT5-amplified exons identified three novel missense mutations. One mutation recurred in two unrelated patients with sporadic EBS. This glutamate to lysine substitution (E477K), located in the highly conserved KLLEGE motif at the end of the central rod domain, is the third recurrent mutation identified in dominant epidermolysis bullosa simplex disease. The corresponding glutamate in keratin 2e was previously reported to be frequently mutated in ichthyosis bullosa of Siemens, suggesting that this highly conserved residue may be a potential mutational hot spot in other type II keratins or nonkeratin intermediate filament proteins.
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Affiliation(s)
- K Stephens
- Department of Medicine, University of Washington, Seattle 98195, U.S.A
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200
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Jonkman MF, Scheffer H, Stulp R, Pas HH, Nijenhuis M, Heeres K, Owaribe K, Pulkkinen L, Uitto J. Revertant mosaicism in epidermolysis bullosa caused by mitotic gene conversion. Cell 1997; 88:543-51. [PMID: 9038345 DOI: 10.1016/s0092-8674(00)81894-2] [Citation(s) in RCA: 182] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Mitotic gene conversion acting as reverse mutation has not been previously demonstrated in human. We report here that the revertant mosaicism of a compound heterozygous proband with an autosomal recessive genodermatosis, generalized atrophic benign epidermolysis bullosa, is caused by mitotic gene conversion of one of the two mutated COL17A1 alleles. Specifically, the maternal allele surrounding the mutation site on COL17A1 (1706delA) showed reversion of the mutation and loss of heterozygosity along a tract of at least 381 bp in revertant keratinocytes derived from clinically unaffected skin patches; the paternal mutation (R1226X) remained present in all cell samples. Revertant mosaicism represents a way of natural gene therapy.
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Affiliation(s)
- M F Jonkman
- Department of Dermatology, University Hospital Groningen, The Netherlands
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