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Phadnis SV, Griffin DR, Eady RA, Rodeck CH, Chitty LS. Prenatal diagnosis and management strategies in a family with a rare type of congenital ichthyosis. Ultrasound Obstet Gynecol 2007; 30:908-10. [PMID: 17663485 DOI: 10.1002/uog.4004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
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Abstract
Epidermolvsis bullosa (EB) is a heterogeneous group of inherited skin fragility and blistering disorders. Over the last 25 years research in EB has progressed from descriptive morphological studies through quantitative ultrastructural and biochemical analysis to molecular genetic approaches, including linkage analysis, gene cloning and sequencing, and mutation screening. Currently, 10 distinct causative genes are known to underlie different forms of EB, and this knowledge has been translated to improving the clinical management of patients with these disorders. For example, first trimester DNA-based prenatal diagnosis is now available in a number of centres in different countries, including Japan, the USA and the UK, and preimplantation genetic diagnosis is also possible. The development of novel forms of treatment for enhancing wound healing and reducing blistering are the subject of an international research effort. Programmes aimed at developing gene therapy for the major forms of EB have already reached the preclinical testing stages. Despite these impressive scientific advances, EB continues to be a devastating disease, in which the high incidence of aggressive squamous cell carcinoma has a major influence on both morbidity and life expectancy, especially in patients with the severe mutilating form of dystrophic EB.
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Affiliation(s)
- R A Eady
- Department of Cell and Molecular Pathology, Guy's, King's, and St Thomas' School of Medicine, St Thomas' Hospital, London, UK
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Whittock NV, Ashton GH, Griffiths WA, Eady RA, McGrath JA. New mutations in keratin 1 that cause bullous congenital ichthyosiform erythroderma and keratin 2e that cause ichthyosis bullosa of Siemens. Br J Dermatol 2001; 145:330-5. [PMID: 11531804 DOI: 10.1046/j.1365-2133.2001.04327.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The intermediate filaments of epithelial cells are formed by keratins, a family of structurally related proteins, which are expressed in pairs of acidic (type I) and basic (type II) polypeptides in a tissue- and differentiation-specific manner. Mutations in the genes encoding several keratins have been implicated in the pathogenesis of diseases of keratinization. We report molecular analysis of two patients with the rare autosomal dominant disorders bullous congenital ichthyosiform erythroderma (BCIE) and ichthyosis bullosa of Siemens (IBS). Previous studies have shown that these genodermatoses are due to mutations in the KRT1 and KRT2E genes, respectively. We report a new amino acid substitution mutation in codon 155 of KRT1 (valine to aspartic acid) in the conserved H1 domain of the protein in the patient with BCIE. We also report a novel amino acid substitution mutation in codon 192 of KRT2E (asparagine to lysine) in the conserved 1A helix initiation peptide of the protein in the patient with IBS. Our results demonstrate that these mutations are deleterious to keratin filament network stability and lead to specific clinical inherited disorders of keratinization.
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Affiliation(s)
- N V Whittock
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, King's College, London, UK.
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Thornhill AR, McGrath JA, Eady RA, Braude PR, Handyside AH. A comparison of different lysis buffers to assess allele dropout from single cells for preimplantation genetic diagnosis. Prenat Diagn 2001; 21:490-7. [PMID: 11438956 DOI: 10.1002/pd.109] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Single cell polymerase chain reaction (PCR) for preimplantation genetic diagnosis (PGD) requires high efficiency and accuracy. Allele dropout (ADO), the random amplification failure of one of the two parental alleles, remains the most significant problem in PCR-based PGD testing since it can result in serious misdiagnosis for compound heterozygous or autosomal dominant conditions. A number of different strategies (including the use of lysis buffers to break down the cell and make the DNA accessible) have been employed to combat ADO with varying degrees of success, yet there is still no consensus among PGD centres over which lysis buffer should be used (ESHRE PGD Consortium, 1999). To address this issue, PCR amplification of three genes (CFTR, LAMA3 and PKP1) at different chromosomal loci was investigated. Single lymphocytes from individuals heterozygous for mutations within each of the three genes were collected and lysed in either alkaline lysis buffer (ALB) or proteinase K/SDS lysis buffer (PK). PCR amplification efficiencies were comparable between alkaline lysis and proteinase K lysis for PCR products spanning each of the three mutated loci (DeltaF508 in CFTR 90% vs 88%; R650X in LAMA3 82% vs 78%; and Y71X in PKP1 91% vs 87%). While there was no appreciable difference between ADO rates between the two lysis buffers for the LAMA3 PCR product (25% vs 26%), there were significant differences in ADO rates between ALB and PK for the CFTR PCR product (0% vs 23%) and the PKP1 PCR product (8% vs 56%). Based on these results, we are currently using ALB in preference to PK/SDS buffer for the lysis of cells in clinical PGD.
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Affiliation(s)
- A R Thornhill
- Guy's and St Thomas' Centre for Preimplantation Genetic Diagnosis, London SE1 7EH, UK.
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Hatsell SJ, Eady RA, Wennerstrand L, Dopping-Hepenstal P, Leigh IM, Munro C, Kelsell DP. Novel splice site mutation in keratin 1 underlies mild epidermolytic palmoplantar keratoderma in three kindreds. J Invest Dermatol 2001; 116:606-9. [PMID: 11286630 DOI: 10.1046/j.1523-1747.2001.13041234.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report a novel mutation in the exon 6 splice donor site of keratin 1 (G4134A) that segregates with a palmoplantar keratoderma in three kindreds. The nucleotide substitution leads to the utilization of a novel in-frame splice site 54 bases downstream of the mutation with the subsequent insertion of 18 amino acids into the 2B rod domain. This mutation appears to have a milder effect than previously described mutations in the helix initiation and termination sequence on the function of the rod domain, with regard to filament assembly and stability. Affected individuals displayed only mild focal epidermolysis in the spinous layer of palmoplantar epidermis, in comparison with cases of bullous congenital ichthyosiform erythroderma also due to keratin 1 mutations, which show widespread and severe epidermolysis. This study describes a novel mutation in KRT1 that results in a phenotype distinct from classical bullous congenital ichthyosiform erythroderma.
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Affiliation(s)
- S J Hatsell
- Center for Cutaneous Research, St. Bartholomews, and the Royal London School of Medicine and Dentistry, Queen Mary College, London, UK
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Abstract
Over the last few years the molecular basis of several inherited skin diseases has been delineated. Some discoveries have stemmed from a candidate gene approach using clinical, biochemical, immunohistochemical, and ultrastructural clues, while others have arisen from genetic linkage and positional cloning analyses. Notable advances have included elucidation of specific gene pathology in the major forms of inherited skin fragility, ichthyosis, and keratoderma. These findings have led to a better understanding of the significance of individual structural proteins and regulatory enzymes in keratinocyte adhesion and differentiation. From a clinical perspective, the advances have led to better genetic counseling in many disorders, the development of DNA-based prenatal diagnosis, and a foundation for planning newer forms of treatment, including somatic gene therapy, in selected conditions.
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Affiliation(s)
- J A McGrath
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, Kings College and St Thomas' Hospital Medical School, St Thomas' Hospital, London, United Kingdom.
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Hunt DM, Rickman L, Whittock NV, Eady RA, Simrak D, Dopping-Hepenstal PJ, Stevens HP, Armstrong DK, Hennies HC, Küster W, Hughes AE, Arnemann J, Leigh IM, McGrath JA, Kelsell DP, Buxton RS. Spectrum of dominant mutations in the desmosomal cadherin desmoglein 1, causing the skin disease striate palmoplantar keratoderma. Eur J Hum Genet 2001; 9:197-203. [PMID: 11313759 DOI: 10.1038/sj.ejhg.5200605] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2000] [Revised: 10/27/2000] [Accepted: 11/01/2000] [Indexed: 11/09/2022] Open
Abstract
The adhesive proteins of the desmosome type of cell junction consist of two types of cadherin found exclusively in that structure, the desmogleins and desmocollins, coded by two closely linked loci on human chromosome 18q12.1. Recently we have identified a mutation in the DSG1 gene coding for desmoglein 1 as the cause of the autosomal dominant skin disease striate palmoplantar keratoderma (SPPK) in which affected individuals have marked hyperkeratotic bands on the palms and soles. In the present study we present the complete exon-intron structure of the DSG1 gene, which occupies approximately 43 kb, and intron primers sufficient to amplify all the exons. Using these we have analysed the mutational changes in this gene in five further cases of SPPK. All were heterozygotic mutations in the extracellular domain leading to a truncated protein, due either to an addition or deletion of a single base, or a base change resulting in a stop codon. Three mutations were in exon 9 and one in exon 11, both of which code for part of the third and fourth extracellular domains, and one was in exon 2 coding for part of the prosequence of this processed protein. This latter mutation thus results in the mutant allele synthesising only 25 amino acid residues of the prosequence of the protein so that this is effectively a null mutation implying that dominance in the case of this mutation was caused by haploinsufficiency. The most severe consequences of SPPK mutations are in regions of the body where pressure and abrasion are greatest and where desmosome function is most necessary. SPPK therefore provides a very sensitive measure of desmosomal function.
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Affiliation(s)
- D M Hunt
- Division of Membrane Biology, National Institute for Medical Research, Mill Hill, London, NW7 1AA, UK
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Ashton GH, Sorelli P, Mellerio JE, Keane FM, Eady RA, McGrath JA. Alpha 6 beta 4 integrin abnormalities in junctional epidermolysis bullosa with pyloric atresia. Br J Dermatol 2001; 144:408-14. [PMID: 11251584 DOI: 10.1046/j.1365-2133.2001.04038.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Junctional epidermolysis bullosa with pyloric atresia (JEB-PA) (MIM 226730) is an autosomal recessive disorder resulting from mutations in the genes encoding alpha 6 beta 4 integrin (ITGA6 and ITGB4). Clinically, it is characterized by mucocutaneous fragility and gastrointestinal atresia, which most commonly affects the pylorus. Additional features of JEB-PA include involvement of the urogenital tract, aplasia cutis and failure to thrive. While most affected individuals have a poor prognosis resulting in death in infancy, others have milder clinical features and a better prognosis. We report two previously undescribed homozygous ITGB4 mutations in two unrelated families, which resulted in severe skin blistering, pyloric atresia and lethality in infancy. Delineation of the mutations was used to undertake DNA-based prenatal diagnosis in subsequent pregnancies at risk for recurrence in both families. We review all previously published ITGA6 and ITGB4 mutation reports to help define genotype--phenotype correlation in this rare genodermatosis.
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Affiliation(s)
- G H Ashton
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, King's College and St Thomas' Hospitals' Medical School, St Thomas' Hospital, Lambeth Palace Road, London SE1 7EH, UK
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Wessagowit V, Ashton GH, Mohammedi R, Salas-Alanis JC, Denyer JE, Mellerio JE, Eady RA, McGrath JA. Three cases of de novo dominant dystrophic epidermolysis bullosa associated with the mutation G2043R in COL7A1. Clin Exp Dermatol 2001; 26:97-9. [PMID: 11260189 DOI: 10.1046/j.1365-2230.2001.00769.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the absence of a positive family history, it is often difficult to determine whether a single case of mild-to-moderately severe dystrophic epidermolysis bullosa (DEB) represents autosomal recessive or de novo dominant disease. Recent molecular analyses of the type VII collagen gene, COL7A1, have established that the vast majority of such cases are recessive in nature. Nevertheless, a small number of de novo dominant patients have been documented. In this report, we describe three further examples of de novo dominant disease. In each case the COL7A1 mutation comprised the same glycine substitution, G2043R. This mutation has previously been reported in both dominant DEB pedigrees and as a de novo phenomenon and is the most common COL7A1 mutation in dominant DEB throughout the world. These cases emphasize the importance of molecular analysis in providing accurate genetic counselling in this genodermatosis.
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Affiliation(s)
- V Wessagowit
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology (GKT), St Thomas's Hospital, London, UK
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Ishida-Yamamoto A, Kato H, Kiyama H, Armstrong DK, Munro CS, Eady RA, Nakamura S, Kinouchi M, Takahashi H, Iizuka H. Mutant loricrin is not crosslinked into the cornified cell envelope but is translocated into the nucleus in loricrin keratoderma. J Invest Dermatol 2000; 115:1088-94. [PMID: 11121146 DOI: 10.1046/j.1523-1747.2000.00163.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Loricrin is a major constituent of the epidermal cornified cell envelope. We have recently identified heterozygous loricrin gene mutations in two dominantly inherited skin diseases, the ichthyotic variant of Vohwinkel syndrome and progressive symmetric erythrokeratoderma, collectively termed loricrin keratoderma. In order to see whether the mutant loricrin molecules predicted by DNA sequencing are expressed in vivo and to define their pathologic effects, we raised antibodies against synthetic peptides corresponding to the mutated sequences of loricrin. Immunoblotting of horny cell extracts from loricrin keratoderma patients showed specific bands for mutant loricrin. Immunohistochemistry of loricrin keratoderma skin biopsies showed positive immunoreactivity to the mutant loricrin antibodies in the nuclei of differentiated epidermal keratinocytes. The immunostaining was localized to the nucleoli of the lower granular cell layer. As keratinocyte differentiation progressed the immunoreactivity moved gradually into the nucleoplasm leaving nucleoli mostly nonimmunoreactive. No substantial staining was observed along the cornified cell envelope. This study confirmed that mutant loricrin was expressed in the loricrin keratoderma skin. Mutant loricrin, as a dominant negative disrupter, is not likely to affect cornified cell envelope crosslinking directly, but seems to interfere with nuclear/nucleolar functions of differentiating keratinocytes. In addition, detection of the mutant loricrin in scraped horny layer could provide a simple noninvasive screening test for loricrin keratoderma. J Invest Dermatol 115:1088-1094 2000
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Affiliation(s)
- A Ishida-Yamamoto
- Department of Dermatology, Asahikawa Medical College, Asahikawa, Japan.
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Thornhill AR, Pickering SJ, Whittock NV, Caller J, Andritsos V, Bickerstaff HE, Handyside AH, Eady RA, Braude PR, McGrath JA. Preimplantation genetic diagnosis of compound heterozygous mutations leading to ablation of plakophilin-1 (PKP1) and resulting in skin fragility ectodermal dysplasia syndrome: a case report. Prenat Diagn 2000; 20:1055-62. [PMID: 11180229 DOI: 10.1002/1097-0223(200012)20:13<1055::aid-pd978>3.0.co;2-#] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A new form of genodermatosis resulting from mutations in the gene plakophilin 1 (PKP1) has recently been identified. The clinical features of a functional knockout of PKP1 are a combination of skin fragility and a form of hypohydrotic ectodermal dysplasia. We have developed a single cell polymerase chain reaction (PCR) assay suitable for preimplantation genetic diagnosis (PGD) and here we report on the clinical application of this assay.
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Affiliation(s)
- A R Thornhill
- Division of Reproductive Endocrinology & Infertility, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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Affiliation(s)
- G H Ashton
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, King's College and St Thomas' Hospitals' Medical School, St Thomas' Hospital, London, UK
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Abstract
Naegeli-Franceschetti-Jadassohn syndrome is a rare autosomal dominant form of ectodermal dysplasia affecting sweat glands, nails, teeth, and skin. We have studied a multigeneration family of Anglo-Saxon British descent using microsatellite markers to screen candidate loci, including the epidermal differentiation complex on 1q, the keratin gene clusters on chromosomes 12q and 17q and the desmosomal cadherin gene cluster on chromosome 18q. Significant genetic linkage to chromosome 17q was observed using marker D17S 1787, with a maximum two-point LOD score of 4.166 at a recombination fraction of theta = 0. Recombination events in the family place the gene in a 26.97 cM interval between markers D17S798 and D17S957, a region known to contain the type I keratin gene cluster and other genes expressed in epithelia. Keratins K15, K19, and K20, plakoglobin, and MEOX1 were excluded as candidates by direct sequencing of genomic polymerase chain reaction products.
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Affiliation(s)
- N V Whittock
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, King's College, and St Thomas' Hospitals' Medical School, London, UK.
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Abstract
Plakoglobin is a globular protein common to the intracellular plaques of adhesive junctions, predominantly desmosomes and adherens junctions. Recently, a number of pathogenic mutations have been described in other components of desmosomes, specifically in plakophilin 1, desmoplakin and desmoglein 1. The phenotype of affected patients mainly involves thickening of palm and sole skin (keratoderma). Although no human mutations in plakoglobin have been described thus far, this protein represents an excellent candidate for other human genetic disorders, possibly involving skin and heart, sites of high plakoglobin expression. To facilitate future mutation detection analyses in such conditions, we have characterized the intron-exon organization of the human plakoglobin gene, which comprises 13 distinct exons spanning approximately 17 kb on 17q21. We have also developed a PCR-based mutation detection strategy using primers placed on flanking introns followed by direct sequencing of the PCR products.
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Affiliation(s)
- N V Whittock
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, King's College, and St Thomas' Hospitals' Medical School, London, UK.
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Whittock NV, Hunt DM, Rickman L, Malhi S, Vogazianou AP, Dawson LF, Eady RA, Buxton RS, McGrath JA. Genomic organization and amplification of the human desmosomal cadherin genes DSC1 and DSC3, encoding desmocollin types 1 and 3. Biochem Biophys Res Commun 2000; 276:454-60. [PMID: 11027496 DOI: 10.1006/bbrc.2000.3500] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The desmosomal cadherins comprise the desmocollins and desmogleins and are involved in epithelial cell-cell adhesion. There are three desmocollins (DSC 1-3) and three desmogleins (DSG 1-3) that are expressed in a tissue- and development-specific manner. Desmosomal proteins have been implicated in a number of disorders characterized by loss of cell-cell adhesion and trauma-induced skin fragility. Therefore, the desmocollins are potential candidates for genodermatoses involving epithelial tissues. In order to screen the entire DSC1 and DSC3 genes, we have characterized their intron-exon organization. The DSC1 gene comprises 17 exons spanning approximately 33 kb on 18q12.1, and the DSC3 gene comprises 17 exons spanning approximately 49 kb on 18q12.1. We have also developed a comprehensive PCR-based mutation detection strategy for desmocollins 1, 2, and 3 using primers placed on flanking introns followed by direct sequencing of the PCR products.
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Affiliation(s)
- N V Whittock
- Department of Cell and Molecular Pathology, St. John's Institute of Dermatology, London, United Kingdom.
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Whittock NV, Haftek M, Angoulvant N, Wolf F, Perrot H, Eady RA, McGrath JA. Genomic amplification of the human plakophilin 1 gene and detection of a new mutation in ectodermal dysplasia/skin fragility syndrome. J Invest Dermatol 2000; 115:368-74. [PMID: 10951270 DOI: 10.1046/j.1523-1747.2000.00082.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ectodermal dysplasia/skin fragility syndrome is a recently described autosomal recessive disease affecting skin, nails, and hair (MIM 604536), that results from mutations in plakophilin 1, a structural component of desmosomes. We report a new plakophilin 1 mutation in an affected patient as well as detailing the intron-exon organization of the gene to facilitate future polymerase chain reaction-based mutation screening. Using polymerase chain reaction amplification of genomic DNA, we identified 15 exons spanning approximately 50 kb. Direct sequencing disclosed several nonpathogenic intragenic polymorphisms, as well as a homozygous splice site mutation (1233-2 A-->T; GenBank Z73678) in a 17 y old affected male. The clinical features comprised skin erosions, dystrophic nails, sparse hair, and painful thickening and cracking of palms and soles. Skin biopsy showed negative immunolabeling with an anti-plakophilin 1 antibody and small desmosomes. These results expand the database of plakophilin 1 mutations and demonstrate the importance of this protein in the stabilization of desmosomal adhesion in terminally differentiating keratinocytes.
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Affiliation(s)
- N V Whittock
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, King's College, and St Thomas' Hospitals' Medical School, St Thomas' Hospital, London, U.K.
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Batta K, Rugg EL, Wilson NJ, West N, Goodyear H, Lane EB, Gratian M, Dopping-Hepenstal P, Moss C, Eady RA. A keratin 14 'knockout' mutation in recessive epidermolysis bullosa simplex resulting in less severe disease. Br J Dermatol 2000; 143:621-7. [PMID: 10971341 DOI: 10.1111/j.1365-2133.2000.03722.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Epidermolysis bullosa simplex (EBS) is a blistering skin disease caused in most cases by mis-sense mutations in genes encoding the basal epidermal keratin (K) 5 and K14. The inheritance is usually autosomal dominant and the mutant keratin proteins appear to exert a dominant negative effect on the keratin intermediate filament cytoskeleton in basal keratinocytes. We report a child with a homozygous K14 mutation resulting in the complete absence of K14 protein in the epidermis; remarkably, he only had mild to moderate disease. Electron microscopy of a skin biopsy showed a marked reduction in numbers of keratin intermediate filaments in the basal keratinocytes. Immunofluorescence microscopy using monoclonal antibody LL001 against K14 showed no staining, suggesting a functional knockout of K14. Sequence analysis of genomic DNA revealed a homozygous mutation in codon 31 of K14 that resulted in a premature stop codon further downstream in exon 1. The child's mother, who is unaffected by the disease, is heterozygous for the mutation. The consanguineous father was unaffected and unavailable for testing. The resulting mRNA is predicted to encode a protein of 116 amino acids, of which the first 30 are identical to the normal K14 sequence, and the remaining 86 residues are mis-sense sequence. Four previously reported cases of autosomal recessive EBS with functional knockout of K14 were severely affected by blistering, in contrast to our patient in whom the predicted protein has only the first 30 amino acids of K14 and is therefore the closest to a true knockout of K14 protein yet identified.
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Affiliation(s)
- K Batta
- Department of Dermatology, The Birmingham Children's Hospital, Birmingham B4 6NL, U.K
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Abstract
Keratins are a family of structurally related proteins that form the intermediate filament cytoskeleton in epithelial cells. Mutations in K1 and K5 result in the autosomal dominant disorders epidermolytic hyperkeratosis/bullous congenital ichthyosiform erythroderma and epidermolysis bullosa simplex, respectively. Most disease-associated mutations are within exons encoding protein domains involved in keratin filament assembly. However, some mutations occur outside the mutation hot-spots and may perturb intermolecular interactions between keratins and other proteins, usually with milder clinical consequences. To screen the entire keratin 1 and keratin 5 genes we have characterized their intron-exon organization. The keratin 1 gene comprises 9 exons spanning approximately 5.6 kb on 12q, and the keratin 5 gene comprises 9 exons spanning approximately 6.1 kb on 12q. We have also developed a comprehensive PCR-based mutation detection strategy using primers placed on flanking introns followed by direct sequencing of the PCR products.
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Affiliation(s)
- N V Whittock
- Department of Cell and Molecular Pathology, St. John's Institute of Dermatology, London, United Kingdom.
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Fine JD, McGrath J, Eady RA. Inherited epidermolysis bullosa comes into the new millenium: a revised classification system based on current knowledge of pathogenetic mechanisms and the clinical, laboratory, and epidemiologic findings of large, well-defined patient cohorts. J Am Acad Dermatol 2000; 43:135-7. [PMID: 10863241 DOI: 10.1067/mjd.2000.107739] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- J D Fine
- Departments of Dermatology and Epidemiology, University of North Carolina at Chapel Hill, 27599-7287, USA
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Corden LD, Mellerio JE, Gratian MJ, Eady RA, Harper JI, Lacour M, Magee G, Lane EB, McGrath JA, McLean WH. Homozygous nonsense mutation in helix 2 of K14 causes severe recessive epidermolysis bullosa simplex. Hum Mutat 2000; 11:279-85. [PMID: 9554744 DOI: 10.1002/(sici)1098-1004(1998)11:4<279::aid-humu5>3.0.co;2-e] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We have studied a consanguineous family containing two children with severe, generalized epidermolysis bullosa simplex (EBS). Electron microscopy of skin biopsies from the affected individuals showed that basal keratinocytes were devoid of tonofilament bundles, although some single intermediate filament were visible. Genetic linkage analysis with the microsatellite probe D12S96 excluded the type II keratin gene cluster in this family. However, homozygosity by descent was observed with the polymorphic probes KRT9, KRT10 Ava II, and D17S1787 in both affected children, consistent with a recessive defect in a type I keratin. Immunoreactivity to keratin K5 and K15 was normal, but monoclonal antibodies LL001 and RCK107 against K14 showed no staining, suggesting a deficiency of K14 in these individuals. mRNA extracted from biopsy material was amplified by RT-PCR to obtain full-length K14 cDNA. Direct automated sequencing identified a homozygous nonsense mutation, W305X. A Hinf I restriction enzyme site is created by this nucleotide transition, which was used to confirm the presence of the mutation in this kindred and exclude it from 100 normal chromosomes. This is the fourth kindred with severe recessive EBS for whom a mutation has been found in the K14 gene. In this instance, the premature termination codon is the farthest downstream of the reported cases, occurring in the helix 2 domain and so giving a much longer translation product. Nevertheless, the heterozygous carriers are unaffected by the disease and display no epidermal fragility. We postulate that translation of the potentially dominant-negative truncated K14 might be down-regulated due to instability of the mutant mRNA, as observed in previous cases with similar mutations.
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Affiliation(s)
- L D Corden
- Department of Anatomy and Physiology, Medical Sciences Institute, University of Dundee, UK
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23
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Fine JD, Eady RA, Bauer EA, Briggaman RA, Bruckner-Tuderman L, Christiano A, Heagerty A, Hintner H, Jonkman MF, McGrath J, McGuire J, Moshell A, Shimizu H, Tadini G, Uitto J. Revised classification system for inherited epidermolysis bullosa: Report of the Second International Consensus Meeting on diagnosis and classification of epidermolysis bullosa. J Am Acad Dermatol 2000; 42:1051-66. [PMID: 10827412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- J D Fine
- University of North Carolina at Chapel Hill, 27599-7287, USA
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24
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Abstract
Keratin intermediate filaments are the major components of the cytoskeleton in epithelial cells. Mutations in keratin genes have been documented in many disorders of the skin, nails, hair, and mucous membranes. Although no mutations have been described in either keratin 15 or keratin 19, they are good candidates for other as yet uncharacterized genetic disorders of keratinization, particularly as the skin, nails, hair, and conjunctiva are sites of keratin 15 and 19 expression. To facilitate future mutation detection analyses, we have therefore characterized the intron-exon organization of the human keratin 15 and keratin 19 genes. The keratin 15 gene comprises 8 exons spanning approximately 5.1 kb on 17q21, and the keratin 19 gene consists of 6 exons covering approximately 4.7 kb on 17q21. We have also developed a PCR-based mutation detection strategy using primers placed on flanking introns followed by direct sequencing of the PCR products.
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Affiliation(s)
- N V Whittock
- St John's Institute of Dermatology, King's College and St. Thomas' Hospitals' Medical School, London, United Kingdom
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25
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Wilgoss A, Leigh IM, Barnes MR, Dopping-Hepenstal P, Eady RA, Walter JM, Kennedy CT, Kelsell DP. Identification of a novel mutation R42P in the gap junction protein beta-3 associated with autosomal dominant erythrokeratoderma variabilis. J Invest Dermatol 1999; 113:1119-22. [PMID: 10594760 DOI: 10.1046/j.1523-1747.1999.00792.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report a missense mutation in the gap junction protein beta-3 (encoding Connexin 31), which was detected in only the affected members of a family in which the autosomal dominant skin disease erythrokeratoderma variabilis was segregating. The nucleotide change results in an arginine to proline substitution in codon 42. This residue is positioned on the first transmembrane/first extracellular domain of the gap junction protein with the mutation replacing a negatively charged residue with a nonpolar residue. This change may disrupt the conformation of the protein and voltage gating polarity leading to impaired channel function.
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Affiliation(s)
- A Wilgoss
- Centre for Cutaneous Research, St. Bartholomew's and the Royal London Hospital School of Medicine and Dentistry, Queen Mary and Westfield College, London, UK
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26
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Whittock NV, Ashton GH, Dopping-Hepenstal PJ, Gratian MJ, Keane FM, Eady RA, McGrath JA. Striate palmoplantar keratoderma resulting from desmoplakin haploinsufficiency. J Invest Dermatol 1999; 113:940-6. [PMID: 10594734 DOI: 10.1046/j.1523-1747.1999.00783.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recently, the first example of a human mutation in the gene encoding the desmosomal plaque protein, desmoplakin, has been described in a patient with autosomal dominant striate palmoplantar kerato-derma. We now report a further case of a desmoplakin mutation in a proband with striate palmoplantar keratoderma that also results in a null allele and haploinsufficiency. The mutation was a heterozygous G > A transition at the donor + 1 site of intron 7 of the desmoplakin gene (939 + 1 G > A; Genbank M77830). The aberrant splicing leads to retention of the entire intron 7, which contains a premature termination codon within the N-terminal domain of the peptide. Because the mutant null allele could not be identified on cDNA sequencing, we determined by polymerase chain reaction the exon-intron organization of the desmoplakin gene to facilitate analysis of genomic DNA. The gene spans approximately 45 kb of chromosome 6 and comprises 24 exons ranging in size from 51 bp to 3922 bp. We have also characterized fully the 3'UTR of the desmoplakin cDNA. This study demonstrates the relevance of haploinsufficiency for desmoplakin in the pathogenesis of this genodermatosis. Assessment of family members bearing the mutant allele also emphasizes the significance of an individual's age and exposure to skin trauma in manifesting full phenotypic expression of the disorder.
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Affiliation(s)
- N V Whittock
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, King's College, and St Thomas' Hospitals' Medical School, St Thomas' Hospital, London, UK. neil.2.whittock
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27
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Whittock NV, Ashton GH, Mohammedi R, Mellerio JE, Mathew CG, Abbs SJ, Eady RA, McGrath JA. Comparative mutation detection screening of the type VII collagen gene (COL7A1) using the protein truncation test, fluorescent chemical cleavage of mismatch, and conformation sensitive gel electrophoresis. J Invest Dermatol 1999; 113:673-86. [PMID: 10504458 DOI: 10.1046/j.1523-1747.1999.00732.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mutations in the type VII collagen gene, COL7A1, give rise to the blistering skin disease, dystrophic epidermolysis bullosa. We have developed two new mutation detection strategies for the screening of COL7A1 mutations in patients with dystrophic epidermolysis bullosa and compared them with an established protocol using conformational sensitive gel electrophoresis. The first strategy consisted of an RNA based protein truncation test that amplified the entire coding region in only four overlapping nested reverse transcriptase-polymerase chain reaction assays. These fragments were transcribed and translated in vitro and analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We have used the protein truncation test procedure to characterize 15 truncating mutations in 13 patients with severe recessive dystrophic epidermolysis bullosa yielding a detection sensitivity of 58%. The second strategy was a DNA-based fluorescent chemical cleavage of mismatch (fl-CCM) procedure that amplified the COL7A1 gene in 21 polymerase chain reaction assays. Mismatches, formed between patient and control DNA, were identified using chemical modification and cleavage of the DNA. We have compared fl-CCM with conformational sensitive gel electrophoresis by screening a total of 50 dominant and recessive dystrophic epidermolysis bullosa patients. The detection sensitivity for fl-CCM was 81% compared with 75% for conformational sensitive gel electrophoresis (p = 0.37 chi2-test). Using a combination of the three techniques we have screened 93 dystrophic epidermolysis bullosa patients yielding an overall sensitivity of 87%, detecting 79 different mutations, 57 of which have not been reported previously. Comparing all three approaches, we believe that no single method is consistently better than the others, but that the fl-CCM procedure is a sensitive, semiautomated, high throughput system that can be recommended for COL7A1 mutation detection.
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Affiliation(s)
- N V Whittock
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, St Thomas' Hospitals' Medical School, London, UK.
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28
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McGrath JA, Ashton GH, Mellerio JE, Salas-Alanis JC, Swensson O, McMillan JR, Eady RA. Moderation of phenotypic severity in dystrophic and junctional forms of epidermolysis bullosa through in-frame skipping of exons containing non-sense or frameshift mutations. J Invest Dermatol 1999; 113:314-21. [PMID: 10469327 DOI: 10.1046/j.1523-1747.1999.00709.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Non-sense mutations on both alleles of either the type VII collagen gene (COL7A1) or the genes encoding laminin 5 (LAMA3, LAMB3, or LAMC2) usually result in clinically severe forms of recessive dystrophic or junctional epidermolysis bullosa, respectively. In this study we assessed two unrelated families whose mutations in genomic DNA predicted severe recessive dystrophic epidermolysis bullosa or junctional epidermolysis bullosa phenotypes but in whom the manifestations were milder than expected. The recessive dystrophic epidermolysis bullosa patients had a homozygous single base-pair frameshift mutation in exon 19 of COL7A1 (2470insG). Clinically, there was generalized blistering but only mild scarring. Skin biopsy revealed positive type VII collagen immunoreactivity and recognizable anchoring fibrils. The junctional epidermolysis bullosa patients were compound heterozygotes for a frameshift/non-sense combination of mutations in exons 3 and 17 of LAMB3 (29insC/Q834X). These patients did not have the lethal form of junctional epidermolysis bullosa but, as adults, displayed the milder generalized atrophic benign epidermolysis bullosa variant. There was undetectable laminin 5 staining at the dermal-epidermal junction using an antibody to the beta3 chain, but faintly positive alpha3 and gamma2 chain labeling, and there was variable hypoplasia of hemidesmosomes. To explain the milder recessive dystrophic epidermolysis bullosa and junctional epidermolysis bullosa phenotypes in these families, reverse transcription-polymerase chain reaction, using RNA extracted from frozen skin, was able to provide evidence for some rescue of mutant mRNA transcripts with restoration of the open- reading frame. In the recessive dystrophic epidermolysis bullosa patients, transcripts containing in-frame skipping of exon 19 of COL7A1 in the cDNA were detected, and in the junctional epidermolysis bullosa patients transcripts with in-frame skipping of exon 17 of LAMB3 were identified. The truncated proteins encoded by these transcripts are expected to lack certain critical domains involved in cell-matrix attachment, but may still be able to contribute to adhesion thereby moderating the severity of the skin blistering. This study shows the limitations in predicting phenotype in epidermolysis bullosa solely based on mutation analysis of genomic DNA and emphasizes the importance of immunohistochemistry, electron microscopy, and mRNA assessment as parallel investigations.
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Affiliation(s)
- J A McGrath
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, King's College and St Thomas' Hospitals' Medical School, St Thomas' Hospital, London, UK.
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29
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Harman KE, Bhogal BS, Eady RA, McGrath JA, Black MM. Defining target antigens in linear IgA disease using skin from subjects with inherited epidermolysis bullosa as a substrate for indirect immunofluorescence microscopy. Br J Dermatol 1999; 141:475-80. [PMID: 10583051 DOI: 10.1046/j.1365-2133.1999.03041.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Identification of target antigens in immunobullous disorders usually involves laborious techniques such as immunoblotting and immunoprecipitation, which do not always provide conclusive data. This is particularly true of linear IgA disease (LAD) in which the target antigen has often proved difficult to identify. As an alternative means of antigen identification in five adult patients with LAD, we performed indirect immunofluorescence (IIF) microscopy on a panel of skin samples taken from subjects with different forms of inherited epidermolysis bullosa (EB). Skin samples were selected that showed a complete absence of immunostaining for a specific basement membrane zone (BMZ) molecule (type VII collagen, laminin 5 or the 180-kDa bullous pemphigoid antigen BP180). In each case, the underlying genetic mutations had been defined and shown to consist of premature termination codons on both alleles of the particular gene, resulting in total ablation of the encoded protein. Two epidermal-binding LAD sera showed BMZ fluorescence on all substrates except BP180-deficient skin, suggesting that the target antigen was BP180, or a closely related molecule. In contrast, two dermal-binding LAD sera were positive on all substrates except the type VII collagen-deficient skin, suggesting that the target antigen was likely to be type VII collagen. One LAD serum sample, which showed combined dermal and epidermal fluorescence on normal salt-split skin, was also positive on all substrates tested, suggesting a target antigen other than type VII collagen, laminin 5 or BP180. The study confirms that LAD is a heterogeneous disorder and illustrates that IIF using a panel of skin samples which lack specific BMZ molecules, taken from subjects with inherited EB, is a relatively simple and useful tool to help identify target antigens in immunobullous disorders.
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Affiliation(s)
- K E Harman
- Departments of Immunofluorescence and Cell and Molecular Pathology, St John's Institute of Dermatology (GKT), St Thomas' Hospital, London SE1 7EH, U.K.
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30
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Fine JD, Eady RA. Tetracycline and epidermolysis bullosa simplex: a new indication for one of the oldest and most widely used drugs in dermatology? Arch Dermatol 1999; 135:981-2. [PMID: 10456349 DOI: 10.1001/archderm.135.8.981] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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31
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Mellerio JE, Ashton GH, Mohammedi R, Lyon CC, Kirby B, Harman KE, Salas-Alanis JC, Atherton DJ, Harrison PV, Griffiths WA, Black MM, Eady RA, McGrath JA. Allelic heterogeneity of dominant and recessive COL7A1 mutations underlying epidermolysis bullosa pruriginosa. J Invest Dermatol 1999; 112:984-7. [PMID: 10383749 DOI: 10.1046/j.1523-1747.1999.00614.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The inherited mechanobullous disease, dystrophic epidermolysis bullosa, is caused by type VII collagen gene (COL7A1) mutations. We studied six unrelated patients with a distinct clinical subtype of this disease, epidermolysis bullosa pruriginosa, characterized by pruritus, excoriated prurigo nodules, and skin fragility. Mutation analysis using polymerase chain reaction amplification of genomic DNA, heteroduplex analysis and direct nucleotide sequencing demonstrated pathogenetic COL7A1 mutations in each case. Four patients had a glycine substitution mutation on one COL7A1 allele (G1791E, G2242R, G2369S, and G2713R), a fifth was a compound heterozygote for a splice site mutation (5532 + 1G-to-A) and a single base pair deletion (7786delG), and a sixth patient was heterozygous for an out-of-frame deletion mutation (6863del16). This study shows that the molecular pathology in patients with the distinctive clinical features of epidermolysis bullosa pruriginosa is heterogeneous and suggests that other factors, in addition to the inherent COL7A1 mutation(s), may be responsible for an epidermolysis bullosa pruriginosa phenotype.
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Affiliation(s)
- J E Mellerio
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology (The Guy's, King's College and St Thomas' Hospitals' Medical School), London, UK
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32
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Rickman L, Simrak D, Stevens HP, Hunt DM, King IA, Bryant SP, Eady RA, Leigh IM, Arnemann J, Magee AI, Kelsell DP, Buxton RS. N-terminal deletion in a desmosomal cadherin causes the autosomal dominant skin disease striate palmoplantar keratoderma. Hum Mol Genet 1999; 8:971-6. [PMID: 10332028 DOI: 10.1093/hmg/8.6.971] [Citation(s) in RCA: 185] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The N-terminal extracellular domain of the cadherins, calcium-dependent cell adhesion molecules, has been shown by X-ray crystallography to be involved in two types of interaction: lateral strand dimers and adhesive dimers. Here we describe the first human mutation in a cadherin present in desmosome cell junctions that removes a portion of this highly conserved first extracellular domain. The mutation, in the DSG1 gene coding for a desmoglein (Dsg1), results in the deletion of the first and much of the second beta-strand of the first cadherin repeat and part of the first Ca2+-binding site, and would be expected to compromise strand dimer formation. It causes a dominantly inherited skin disease, striate palmoplantar keratoderma (SPPK), mapping to chromosome 18q12.1, in which affected individuals have marked hyperkeratotic bands on the palms and soles. In a three generation Dutch family with SPPK, we have found a G-->A transition in the 3" splice acceptor site of intron 2 of the DSG1 gene which segregated with the disease phenotype. This causes aberrant splicing of exon 2 to exon 4, which are in-frame, with the consequent removal of exon 3 encoding part of the prosequence, the mature protein cleavage site and part of the first extracellular domain. This mutation emphasizes the importance of this part of the molecule for cadherin function, and of the Dsg1 protein and hence desmosomes in epidermal function.
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Affiliation(s)
- L Rickman
- Division of Membrane Biology, National Institute for Medical Research, The Ridgeway, Mill Hill, London, UK
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33
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Ashton GH, Mellerio JE, Dunnill MG, Milana G, Mayou BJ, Carrera J, McGrath JA, Eady RA. Recurrent molecular abnormalities in type VII collagen in Southern Italian patients with recessive dystrophic epidermolysis bullosa. Clin Exp Dermatol 1999; 24:232-5. [PMID: 10354186 DOI: 10.1046/j.1365-2230.1999.00461.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In this study we searched for mutations in the type VII collagen gene (COL7A1) in 10 families from Southern Italy with severe generalised recessive dystrophic epidermolysis bullosa using PCR amplification of genomic DNA, heteroduplex analysis and direct nucleotide sequencing. Our principal aim was to identify any recurrent mutations in COL7A1 that might facilitate future mutation detection strategies in this population. Three recurrent COL7A1 mutations were delineated in six of the 10 families: a frameshift mutation in exon 4, 497insA, was detected in three affected individuals from three families, a deletion mutation at the acceptor splice site of intron 114/exon 115, 8441-14del21, was found in five patients in three of the families, and an intron 49 acceptor splice site mutation, 4783-1 G-to-A, was identified in three subjects in two families (GenBank accession no, L02870). Haplotype analyses showed evidence for propagation of common ancestral mutant COL7A1 alleles for each of these recurrent mutations. These results contribute significantly to understanding the nature of COL7A1 pathology in patients from Southern Italy and in designing future approaches to mutation detection.
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Affiliation(s)
- G H Ashton
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, King's College and St Thomas' Hospitals' Medical School
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Basarab T, Smith FJ, Jolliffe VM, McLean WH, Neill S, Rustin MH, Eady RA. Ichthyosis bullosa of Siemens: report of a family with evidence of a keratin 2e mutation, and a review of the literature. Br J Dermatol 1999; 140:689-95. [PMID: 10233323 DOI: 10.1046/j.1365-2133.1999.02772.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report a large family with ichthyosis bullosa of Siemens (IBS) including eight affected members spanning three generations. The classical features of the disease were consistently observed with blistering, superficial peeling of the skin, and localized lichenified hyperkeratosis mainly confined to the limbs. Phenotypic variation, however, was also observed with some individuals exhibiting unusual clinical features. Specifically, the index patient was erythrodermic at birth; she subsequently developed a widespread pustular eruption. Erythroderma is classically absent in IBS and pustulation is very unusual. She also had hypertrichosis of the limbs, as did an affected female first cousin. This has not previously been reported in IBS. Electron microscopy showed complex aggregates of keratin in the spinous and granular layers associated, in places, with remarkably little cell lysis. Sequencing of genomic DNA revealed a mutation (E493K) in keratin 2e. A review of the literature on IBS indicates that E493K is the most commonly reported mutation to date and might represent a mutational hotspot for this disease.
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Affiliation(s)
- T Basarab
- St John's Institute of Dermatology, St Thomas' Hospital, London SE1 7EH, U.K
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35
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McGrath JA, Hoeger PH, Christiano AM, McMillan JR, Mellerio JE, Ashton GH, Dopping-Hepenstal PJ, Lake BD, Leigh IM, Harper JI, Eady RA. Skin fragility and hypohidrotic ectodermal dysplasia resulting from ablation of plakophilin 1. Br J Dermatol 1999; 140:297-307. [PMID: 10233227 DOI: 10.1046/j.1365-2133.1999.02667.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report a 2-year-old boy with an unusual autosomal recessively inherited skin disease comprising trauma-induced skin fragility and congenital ectodermal dysplasia affecting hair, nails and sweat glands. Skin biopsy showed widening of intercellular spaces between keratinocytes and ultrastructural findings of small, poorly formed desmosomes with reduced connections to the keratin filament cytoskeleton. Immunohistochemical analysis revealed a complete absence of staining for the accessory desmosomal plaque protein plakophilin 1 (PKP1; band 6 protein). The affected individual was a compound heterozygote for null mutations on both alleles of the PKP1 gene. Both mutations occurred within the amino terminus of PKP1, the domain which normally binds the cytoskeletal keratin filament network to the cell membrane. Apart from its localization within desmosomal plaques, PKP1 may also be present within the cytoplasm and nucleus and has putative roles in signal transduction and regulation of gene activity. The clinicopathological observations in this patient demonstrate the relevance of PKP1 to desmosome formation, cutaneous cell-cell adhesion and epidermal development and demonstrate the specific manifestations of human functional knockout mutations in this gene.
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Affiliation(s)
- J A McGrath
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology (Guy's, Kings College and St Thomas' Hospitals' Medical School), St Thomas' Hospital, London SE1 7EH, U.K.
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36
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Mellerio JE, Salas-Alanis JC, Amaya-Guerra M, Tamez E, Ashton GH, Mohammedi R, Eady RA, McGrath JA. A recurrent frameshift mutation in exon 19 of the type VII collagen gene (COL7A1) in Mexican patients with recessive dystrophic epidermolysis bullosa. Exp Dermatol 1999; 8:22-9. [PMID: 10206718 DOI: 10.1111/j.1600-0625.1999.tb00344.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dystrophic epidermolysis bullosa (DEB) is an inherited blistering skin disorder caused by mutations in the type VII collagen gene (COL7A1). In this study, we determined the molecular basis of autosomal recessive DEB in a 19-year-old Hispanic Mexican woman by PCR amplification of genomic DNA, heteroduplex analysis, and automated sequencing of heteroduplex bandshifts. This approach revealed a homozygous frameshift mutation, 2470insG, in exon 19 of COL7A1 and resulted in attenuated basement membrane zone expression of type VII collagen, a reduced number of anchoring fibrils at the dermal-epidermal junction, and a sub-lamina densa level of blister formation. Clinically, the patient had widespread trauma-induced skin fragility and complete loss of the nails, but had less pseudosyndactyly of the fingers and toes and milder mucosal involvement compared to most patients with the generalized form of this genodermatosis. We also screened 7 other Hispanic-Mexican patients with recessive DEB, none of whom were known to be related to this individual, for the mutation 2470insG using heteroduplex analysis and direct sequencing and detected this mutation on 7/14 alleles. Haplotype analysis using intragenic COL7A1 and flanking polymorphisms and microsatellite markers revealed that all the mutant alleles had arisen on similar allelic backgrounds, consistent with propagation of a common Hispanic Mexican ancestral haplotype. In view of the high allelic frequency of the mutation 2470insG in the patients studied, we recommend initial screening for this mutation when attempting to identify the molecular pathology of recessive DEB in Hispanic Mexican patients.
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Affiliation(s)
- J E Mellerio
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, St Thomas's Hospital, London, UK
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37
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Mohammedi R, Mellerio JE, Ashton GH, Eady RA, McGrath JA. A recurrent COL7A1 mutation, R2814X, in British patients with recessive dystrophic epidermolysis bullosa. Clin Exp Dermatol 1999; 24:37-9. [PMID: 10233647 DOI: 10.1046/j.1365-2230.1999.00404.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mutations in the type VII collagen gene, COL7A1, underlie all forms of dystrophic epidermolysis bullosa (DEB). The identification of COL7A1 mutations in DEB is complicated because the COL7A1 gene contains 118 distinct exons and most mutations are specific to individual families. In an attempt to simplify mutation screening procedures we searched for recurrent mutations in genomic DNA from 38 British patients with recessive DEB using polymerase chain reaction (PCR), heteroduplex analysis and direct nucleotide sequencing. We identified a recurrent premature termination codon, R2814X, on three out of 76 alleles. Previously we identified the COL7A1 mutations R578X and 7786delG as other frequent molecular abnormalities in British recessive DEB patients. Taken together, these three mutations account for approximately 25% of the molecular pathology of this disease in our population discovered thus far and we recommend initial screening for these mutations by PCR and restriction analysis before undertaking more exhaustive COL7A1 gene analysis. Such an approach is likely to reveal underlying COL7A1 mutations in a significant number of cases.
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Affiliation(s)
- R Mohammedi
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, The Guy's, King's College and St Thomas' Hospitals Medical School, St Thomas' Hospital, London, UK
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38
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Armstrong DK, McKenna KE, Purkis PE, Green KJ, Eady RA, Leigh IM, Hughes AE. Haploinsufficiency of desmoplakin causes a striate subtype of palmoplantar keratoderma. Hum Mol Genet 1999; 8:143-8. [PMID: 9887343 DOI: 10.1093/hmg/8.1.143] [Citation(s) in RCA: 216] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Desmosomes are highly organized intercellular adhesive junctions that are particularly prominent in epidermis and other tissues experiencing mechanical stress. Desmoplakin, a constitutive component of the desmosomal plaque, is the most abundant protein present in such junctions and plays a critical role in linking the intermediate filament network to the plasma membrane in these tissues. Here we report the first mutation in the gene encoding desmoplakin. The identified mutation, resulting in a null allele and haploinsufficiency, was observed in genomic DNA from a kindred with the dominantly inherited skin disorder, striate palmoplantar keratoderma. Affected individuals had a linear pattern of skin thickening on the fingers and palms and circumscribed areas of skin thickening on the soles. Affected skin demonstrated loosening of intercellular connections, disruption of desmosome-keratin intermediate filament interactions and a proportion of rudimentary desmosomal structures. The disorder mapped to chromosome 6p21 with a maximum lod score of 10.67. The mutation was a heterozygous C-->T transition in exon 4 of the desmoplakin gene and predicted a premature termination codon in the N-terminal region of the peptide. This is the first reported mutation of desmo-plakin and also the first inherited skin disorder in which haploinsufficiency of a structural component has been implicated. It identifies dosage of desmoplakin as critical in maintaining epidermal integrity.
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Affiliation(s)
- D K Armstrong
- Department of Medical Genetics, The Queen's University of Belfast, Belfast City Hospital, Belfast BT9 7AB, UK
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39
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Abstract
Focal dermal hypoplasia is a rare genodermatosis characterized by developmental defects of the skin, resulting in widespread linear lesions of dermal hypoplasia with adipose tissue in the dermis. We describe a 13-year-old girl who has typical cutaneous lesions which have been present since birth; she also has some of the associated dental, nail and skeletal abnormalities, while an X-ray of the long bones osteopathia striata is visible, a feature seen in a high proportion of cases of focal dermal hypoplasia. Eighty-eight per cent of the case reports in the literature are of females and X-linked dominance is the likely mode of inheritance. It has also been proposed that the condition is lethal in homozygous males and the high frequency of miscarriages on the maternal side of this patient's family is consistent with that lethality in males. The literature, particularly with regard to pathogenesis and inheritance, is discussed.
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Affiliation(s)
- C M Hardman
- Department of Dermatology, St Mary's Hospital, Praed Street, London
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40
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Swensson O, Langbein L, McMillan JR, Stevens HP, Leigh IM, McLean WH, Lane EB, Eady RA. Specialized keratin expression pattern in human ridged skin as an adaptation to high physical stress. Br J Dermatol 1998; 139:767-75. [PMID: 9892940 DOI: 10.1046/j.1365-2133.1998.02499.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have analysed the expression of keratins in the epidermis of normal human palm and sole skin (ridged skin) using immunohistochemistry and in situ hybridization. The epidermis of human ridged skin expresses a more complex pattern of keratins than thin skin, which is probably due to the greater stress that ridged skin has to withstand. In addition to keratin K9, we document specific expression patterns of keratins K6, K16 and K17 which are suggestive of regional adaptations of this epidermis to a high cell turnover rate. In particular, the sequestered location of nests of K17-positive cells at the bottom of the deep primary epidermal ridges supports the notion of functional heterogeneity of basal cells and suggests that the K17-positive sites may include stem cells. Expression of K6 and K16 in some basal and most suprabasal keratinocytes is compatible with a constitutively high proliferative activity of normal ridged epidermis, but may also reflect different physical properties of the suprabasal cells, in contrast with regions expressing K9. The distinct labelling patterns observed in primary and secondary epidermal ridges as well as epidermal layers above dermal papillae suggest the existence of local microenvironmental niches leading to differences in keratinocyte differentiation.
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Affiliation(s)
- O Swensson
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology, United Medical and Dental Schools, St Thomas' Campus, London, U.K
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41
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Shemanko CS, Mellerio JE, Tidman MJ, Lane EB, Eady RA. Severe palmo-plantar hyperkeratosis in Dowling-Meara epidermolysis bullosa simplex caused by a mutation in the keratin 14 gene (KRT14). J Invest Dermatol 1998; 111:893-5. [PMID: 9804355 DOI: 10.1046/j.1523-1747.1998.00388.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mutant keratins 5 or 14 are implicated in the etiology of epidermolysis bullosa simplex (EBS). The catalog of mutations has established certain patterns of mutation clusters from which it may be possible, along with associated biochemical data, to predict phenotypic severity. It is becoming apparent that some of these assumptions may now require modification. We report a mutation in the gene encoding keratin 14 (KRT14) that changes the predicted amino acid at position 119, at the start of the helix initiation motif, from methionine to threonine (K14 M119T) in a patient with an EBS Dowling-Meara phenotype with severe palmo-plantar hyperkeratosis. This demonstrates that the three major types of EBS can arise from missense mutations in the same codon. The findings suggest that the specific nature of the missense mutation, in the context of the protein sequence, can contribute far more to the clinical severity than previously thought. The different EBS subtypes should be viewed as gradations of clinical severity rather than distinct genetic diseases.
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Affiliation(s)
- C S Shemanko
- Department of Anatomy and Physiology, University of Dundee, UK
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42
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Mellerio JE, Pulkkinen L, McMillan JR, Lake BD, Horn HM, Tidman MJ, Harper JI, McGrath JA, Uitto J, Eady RA. Pyloric atresia-junctional epidermolysis bullosa syndrome: mutations in the integrin beta4 gene (ITGB4) in two unrelated patients with mild disease. Br J Dermatol 1998; 139:862-71. [PMID: 9892956 DOI: 10.1046/j.1365-2133.1998.02515.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Junctional epidermolysis bullosa associated with pyloric atresia (EB-PA; OMIM 226730) is a rare autosomal recessively inherited disease in which mucocutaneous fragility is associated with gastrointestinal atresia. This disease is usually fatal within the first few weeks or months of life even following surgical correction of the intestinal obstruction. Recently, mutations in the genes encoding the epithelial integrin alpha6beta4 (ITGA6 and ITGB4) have been identified in several patients with EB-PA. We report two unrelated patients with this disease who have survived into early childhood with mild cutaneous involvement, in whom we have identified pathogenetic mutations in ITGB4. The first patient was a compound heterozygote for a splice site mutation in exon 30 (3793 + 1G-to-A) and a non-sense mutation in exon 36 (W1478X), and the second was a compound heterozygote for a missense mutation in exon 3 (C38R) and a 1 bp deletion in exon 36 (4776delG). Although the non-sense and deletion mutations are predicted to result in markedly reduced beta4 integrin mRNA levels, the presence of the missense or splice site mutation on the second allele may enable the synthesis of some functional, albeit perturbed, beta4 polypeptide. Determination of the molecular mechanisms in these two cases increases our understanding of EB-PA and may enable correlation between genotype and phenotype.
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Affiliation(s)
- J E Mellerio
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology (GKT), St Thomas' Hospital, London SE1 7EH, U.K
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43
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Mellerio JE, Salas-Alanis JC, Talamantes ML, Horn H, Tidman MJ, Ashton GH, Eady RA, McGrath JA. A recurrent glycine substitution mutation, G2043R, in the type VII collagen gene (COL7A1) in dominant dystrophic epidermolysis bullosa. Br J Dermatol 1998; 139:730-7. [PMID: 9892921 DOI: 10.1046/j.1365-2133.1998.02496.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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). Nearly all cases of dominant DEB are caused by glycine substitution mutations occurring within the triple helical region of type VII collagen, and most of the mutations are unique to individual families. In this study, we identified a patient of Hispanic-Mexican origin with a mild form of DEB, which resulted from a de novo dominant glycine substitution, G2043R, in exon 73 of COL7A1. We also investigated a Scottish family with a three-generation pedigree of dominant DEB, in whom the same glycine to arginine substitution mutation was demonstrated. This particular mutation has also been detected previously in three other families with dominant DEB: one Italian, one Hungarian and one Norwegian. Given the widespread geographical distribution of this mutation and the demonstration of its occurrence as a de novo event, G2043R therefore represents the first example of a mutational hotspot in dominant DEB. Interestingly, although both the Mexican and Scottish families we studied had some clinical features in keeping with the Pasini form of the disorder, there was considerable interfamilial variability as well as intrafamilial diversity in the affected individuals.
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Affiliation(s)
- J E Mellerio
- Department of Cell and Molecular Pathology, St John's Institute of Dermatology (The Guy's, King's College and St Thomas' Hospitals' Medical and Dental School), St Thomas' Hospital, Lambeth Palace Road, London SE1 7EH, U.K
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44
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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45
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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46
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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47
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McMillan JR, McGrath JA, Tidman MJ, Eady RA. Hemidesmosomes show abnormal association with the keratin filament network in junctional forms of epidermolysis bullosa. J Invest Dermatol 1998; 110:132-7. [PMID: 9457907 DOI: 10.1046/j.1523-1747.1998.00102.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Junctional epidermolysis bullosa is a group of hereditary bullous disorders resulting from defects in several hemidesmosome-anchoring filament components. Because hemidesmosomes are involved not only in keratinocyte-extracellular matrix adherence, but also in normal anchorage of keratin intermediate filaments to the basal keratinocyte membrane, we questioned whether this intracellular function of hemidesmosomes was also perturbed in junctional epidermolysis bullosa. We used quantitative electron microscopic methods to assess certain morphologic features of hemidesmosome-keratin intermediate filaments interactions in skin from normal subjects (n = 11) and from patients with different forms of junctional epidermolysis bullosa (n = 13). In addition, skin from patients with autosomal recessive epidermolysis bullosa simplex with plectin defects (n = 3) or with autosomal recessive dystrophic epidermolysis bullosa (n = 4) were included as controls. Values were expressed as a percentage of the total number of hemidesmosomes counted. In normal skin 83.3% +/- 3.3 (SEM) hemidesmosomes were associated with keratin intermediate filaments and 90.1% +/- 1.9 had inner plaques. In Herlitz junctional epidermolysis bullosa (laminin 5 abnormalities, n = 4) these values were reduced to 45.3% +/- 11.5 (p < 0.001; analysis of variance) and 50.3% +/- 12.8 (p < 0.001), respectively. In junctional epidermolysis bullosa with pyloric atresia (alpha6beta4 abnormalities, n = 3) the values were also reduced [41.8% +/- 7.0 (p < 0.001) and 44.5% +/- 5.7 (p < 0.001), respectively]. In the non-Herlitz group (laminin 5 mutations, n = 3) the counts were 66.7% +/- 7.1 (p > 0.05) and 70.5% +/- 8.5 (p < 0.05), and in skin from patients with bullous pemphigoid antigen 2 mutations (n = 3) the counts were 54.3% +/- 13.8 (p < 0.01) and 57.1% +/- 13.9 (p < 0.01). In epidermolysis bullosa simplex associated with plectin mutations the values were 31.9% +/- 8.9 (p < 0.001) for keratin intermediate filaments association and 39.9% +/- 7.1 (p < 0.001) for inner plaques. Findings in recessive dystrophic epidermolysis bullosa patients' skin were indistinguishable from normal control skin with inner plaques (90.5% +/- 2.5) and keratin intermediate filaments attachment (86.3% +/- 2.1). These findings suggest that the molecular abnormalities underlying different forms of junctional epidermolysis bullosa appear to affect certain critical intracellular functions of hemidesmosomes, such as the normal connections with keratin intermediate filaments. This may have important implications for the maintenance of basal keratinocyte integrity and resilience in junctional epidermolysis bullosa.
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Affiliation(s)
- J R McMillan
- Department of Cell Pathology, St John's Institute of Dermatology, UMDS, St Thomas's Hospital, London, UK
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48
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Kirtschig G, Caux F, McMillan JR, Bedane C, Aberdam D, Ortonne JP, Eady RA, Prost C. Acquired junctional epidermolysis bullosa associated with IgG autoantibodies to the beta subunit of laminin-5. Br J Dermatol 1998; 138:125-30. [PMID: 9536235 DOI: 10.1046/j.1365-2133.1998.02038.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We report the case of a 72-year-old man with clinical features resembling those of non-lethal junctional epidermolysis bullosa associated with IgG autoantibodies to the beta chain of laminin-5. The patient presented with a sudden onset of blistering and severe fragility of the skin and mucous membranes resulting in atrophic scars. Electron microscopy showed that the blistering arose in the lamina lucida. Indirect immunofluorescence indicated that the autoantibodies bound to the dermal side of 1 mol/L NaCl-split skin, and both direct and indirect immunoelectron microscopy demonstrated antibody binding to the lamina densa. Postembedding immunogold electron microscopy also revealed labelling in the lamina lucida beneath the hemidesmosomes. On immunoblotting, we found the autoantibodies to comigrate with the beta chain of laminin-5. Following the nomenclature of inherited junctional epidermolysis bullosa with mutations of the laminin-5 gene, we propose the name acquired junctional epidermolysis bullosa for this newly recognized disease.
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Affiliation(s)
- G Kirtschig
- Department of Dermatology, University Hospital, Marburg, Germany
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49
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McGrath JA, Eady RA. Molecular basis of blistering skin diseases. Hosp Med 1998; 59:28-32. [PMID: 9798561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
Abstract
Structural molecules in the skin may serve as candidate proteins or target antigens in both inherited and acquired blistering skin diseases. Molecular characterization of the proteins and genes that encode them has led to an improved understanding of the mechanisms of blistering in the skin, and has also allowed the development of new approaches to diagnosis and treatment.
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Affiliation(s)
- J A McGrath
- St John's Institute of Dermatology (UMDS), St Thomas' Hospital, London
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50
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Mellerio JE, Smith FJ, McMillan JR, McLean WH, McGrath JA, Morrison GA, Tierney P, Albert DM, Wiche G, Leigh IM, Geddes JF, Lane EB, Uitto J, Eady RA. Recessive epidermolysis bullosa simplex associated with plectin mutations: infantile respiratory complications in two unrelated cases. Br J Dermatol 1997; 137:898-906. [PMID: 9470905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Plectin is a 500 kDa protein involved in cytoskeleton-plasma membrane attachment with a wide tissue distribution including cutaneous and airway epithelia, muscle and neuronal tissue. Recently, mutations in the gene encoding plectin (PLEC1) have been implicated in the pathogenesis of an autosomal recessive variant of epidermolysis bullosa simplex in which cutaneous blistering starting in the neonatal period is associated with muscular dystrophy in later life. In this study, we report two unrelated patients, both of consanguineous parentage, who presented with cutaneous blistering and a hoarse cry from birth. Both experienced inspiratory stridor and respiratory distress, necessitating emergency tracheostomy in one case. Immunoreactivity to monoclonal antibodies against plectin was absent or markedly reduced in skin biopsies from both patients. Electron microscopy revealed a low intraepidermal plane of cleavage and hypoplastic hemidesmosomes with a reduced association with keratin intermediate filaments. Direct sequencing of PLEC1 in each case demonstrated two novel homozygous frameshift deletion mutations, 5069del19 and 5905del2, which both create downstream premature termination codons. Although currently neither patient has symptoms of muscle disease, the identification of mutations in PLEC1 may be predictive for the future development of muscular dystrophy. Recessive epidermolysis bullosa simplex resulting from abnormalities in plectin should be considered in the differential diagnosis blistering, hoarseness and stridor in infancy.
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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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