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Marcel F Jonkman - One of the best experts on this subject based on the ideXlab platform.

  • mutation in exon 1a of plec leading to disruption of plectin isoform 1a causes autosomal recessive skin only Epidermolysis Bullosa Simplex
    Human Molecular Genetics, 2015
    Co-Authors: Katarzyna B Gostynska, Gerhard Wiche, Miranda Nijenhuis, H H Lemmink, Anna M G Pasmooij, Kristin Kernland Lang, Maria J Castanon, Marcel F Jonkman
    Abstract:

    PLEC, the gene encoding the cytolinker protein plectin, has eight tissue-specific isoforms in humans, arising by alternate splicing of the first exon. To date, all PLEC mutations that cause Epidermolysis Bullosa Simplex (EBS) were found in exons common to all isoforms. Due to the ubiquitous presence of plectin in mammalian tissues, EBS from recessive plectin mutations is always associated with extracutaneous involvement including muscular dystrophy, pyloric atresia and cardiomyopathy. We studied a consanguineous family with sisters having isolated blistering suggesting EBS. Skin disease started with foot blisters at walking age and became generalized at puberty while sparing mucous membranes. DNA sequencing revealed a homozygous nonsense mutation (c.46C > T; p.Arg16X) in the first exon of the plectin variant encoding plectin isoform 1a (P1a). Immunofluorescence antigen mapping, transmission electron microscopy, western blot analysis and qRT-PCR were performed on patient skin and cultured keratinocytes, control myocardium and striated muscle samples. We found hypoplastic hemidesmosomes and intra-epidermal 'pseudo-junctional' cleavage fitting EBS. Screening for cardiomyopathy and muscle dystrophy showed no abnormalities. We report the first cases of autosomal-recessive EBS from P1a deficiency affecting skin, while mucous membranes, heart and muscle are spared. The dominant expression of the P1a isoform in epidermal basal cell layer and cultured keratinocytes suggests that mutations in the first exon of isoform 1a cause skin-only EBS without extracutaneous involvement. Our study characterizes yet another of the eight isoforms of plectin and adds a tissue-specific phenotype to the spectrum of 'plectinopathies' produced by mutations of unique first exons of this gene.

  • extensive acantholysis as the major histological feature of a severe case of dowling meara Epidermolysis Bullosa Simplex a reappraisal of acantholysis in the newborn
    European Journal of Dermatology, 2011
    Co-Authors: Esteve Darwich, Marcel F Jonkman, Asuncion Vicente, Maria C Bolling, Maria Antonia Gonzalezensenat, Victoria Cusi, Claudia Fortuny, Jose A Bombi, J M Mascaro
    Abstract:

    Epidermolysis Bullosa (EB) is a heterogeneous group of inherited skin disorders characterized by blistering and skin fragility secondary to mechanical trauma. Epidermolysis Bullosa Simplex (EBS) is the most frequent form of EB, with Dowling-Meara (DM-EBS) subtype being the most severe form in this group. Conventional histopathological evaluation is usually of low value in the diagnosis of EB, and significant histological features have rarely been reported in this group of diseases. We describe a case of severe DM-EBS in which acantholysis was observed in the histological examination. This finding led us to consider other diagnoses, such as neonatal pemphigus vulgaris or lethal acantholytic EB. Histological, immunological, ultrastructural and genetic tests were performed, leading to a final diagnosis of DM-EBS. Therefore, we believe that DM-EBS should be considered in the differential diagnosis of a newborn with blisters, where acantholysis is the main histological feature.

  • mutations in krt5 and krt14 cause Epidermolysis Bullosa Simplex in 75 of the patients
    British Journal of Dermatology, 2011
    Co-Authors: M C Bolling, H H Lemmink, G H L Jansen, Marcel F Jonkman
    Abstract:

    P>Background Epidermolysis Bullosa Simplex (EBS) is a mechanobullous genodermatosis that may be caused by mutations in the genes KRT5 and KRT14 encoding the basal epidermal keratins 5 (K5) and 14 (K14). Three main clinical subtypes of EBS exist, differing in onset, distribution and severity of skin blistering. Previous reports of KRT5 and KRT14 mutations suggest a correlation between the location of the mutation and the severity of the associated EBS phenotype. Objectives The prevalence of KRT5/KRT14 mutations and the genotype-phenotype correlation in the largest tissue-confirmed EBS population is investigated. Methods KRT5 and KRT14 genomic DNA and cDNA sequences of 76 clinically well-defined unrelated EBS probands were amplified and then subjected to direct sequencing and product length analysis. Immunofluorescence microscopy on patients' skin biopsies with antibodies against K5 and K14 was performed to study protein expression. Results In 57 of 76 (75%) probands 41 different KRT5 and KRT14 mutations were identified, of which 12 were novel. Mutations affecting the highly conserved helix boundary motifs of the rod domains of K5 and K14, and the K14 helix initiation motif in particular, were associated with the severest, EBS Dowling-Meara, phenotype. In 21 EBS probands (37%) the mutation was de novo. In 19 probands (25%) KRT5 or KRT14 mutations were excluded. Conclusions The phenotype-genotype correlation observed in this large EBS population underscores the importance of helix boundary motifs for keratin assembly. Only three-quarters of biopsy-confirmed EBS probands have KRT5 or KRT14 mutations, indicating genetic heterogeneity in EBS. Alternative gene candidates are discussed.

  • recessive Epidermolysis Bullosa Simplex phenotype reproduced in vitro ablation of keratin 14 is partially compensated by keratin 17
    American Journal of Pathology, 2003
    Co-Authors: Marcel F Jonkman, Abdoelwaheb El Ghalbzouri, Johanna Kempenaar, Maria Ponec
    Abstract:

    Recessive Epidermolysis Bullosa Simplex (REBS) is characterized by generalized cutaneous blistering in response to mechanical trauma. This results from fragility of the basal keratinocytes that lack keratin tonofilaments because of homozygote null mutation in the keratin 14 gene. REBS patients display in addition focal dyskeratotic skin lesions with histology of epidermolytic hyperkeratosis (EHK) and tonofilament clumping in the suprabasal layers of the epidermis. In this study we examined whether it is possible to mimic in vitro the bullous and dyskeratotic cellular phenotype. For this purpose, fibroblasts from nondyskeratotic (K14−/−) and dyskeratotic (K14−/−) skin of a REBS patient and fibroblasts from a healthy donor (K14+/+) were isolated and incorporated into collagen matrices. Subsequently, fresh biopsies originating from the nondyskeratotic and dyskeratotic skin of the patient and from a healthy donor were placed onto the collagen matrices and cultured at the air-liquid interface. Epidermal morphogenesis was evaluated on the basis of tissue morphology and the expression of a series of keratins. The results of the present study indicate that basal cell vacuolization in REBS can be mimicked in vitro but not the EHK. Fibroblasts seem to play an important regulatory role in establishing the REBS phenotype. These findings suggest that wild-type fibroblasts may enhance the stability of K14−/− keratinocytes in vitro.

  • mutation analysis of the entire keratin 5 and 14 genes in patients with Epidermolysis Bullosa Simplex and identification of novel mutations
    Human Mutation, 2003
    Co-Authors: Petra H L Schuilengahut, Charles H C M Buys, Marcel F Jonkman, Pieter Van Der Vlies, Esme Waanders, H Scheffer
    Abstract:

    Epidermolysis Bullosa Simplex is a group of blistering skin disorders caused by defects in one of the keratin genes, KRT5 and KRT14. Previously reported KRT5 and KRT14 mutations are clustered in several hotspots, namely the rod ends of the 1A and 2B domains and in the non-helical linker region L12. Therefore, genomic KRT5 and KRT14 mutation analysis was initially limited to these hotspots. In this study we describe the screening of nine EBS patients for mutations in the hotspots. In two patients, with the Koebner and the Weber-Cockayne subtypes of Epidermolysis Bullosa Simplex respectively, we could, however, not identify any mutation in one of the hotspot domains of KRT5 and KRT14. Therefore, it appeared to be necessary to screen the entire genes for mutations. For KRT5, a complete genomic mutation detection system was previously described. We now developed a complete genomic mutation detection system for KRT14. For the amplification of the KRT14 genes, we make use of restriction sites to exempt the keratin 14 pseudogene sequence from polymerase chain reaction amplification. Using the complete genomic mutation detection system for both KRT5 and KRT14, we identified four novel KRT5 mutations (IVS1-1G>C, K404E, A438D, E475K), two of which are outside the KRT5 hotspot domains, and three novel KRT14 mutations (IVS4+1G>A, L408M, L130P).

Pierre A Coulombe - One of the best experts on this subject based on the ideXlab platform.

  • Defining keratin protein function in skin epithelia: Epidermolysis Bullosa Simplex and its aftermath
    2016
    Co-Authors: Pierre A Coulombe, Chang-hun Lee
    Abstract:

    Epidermolysis Bullosa Simplex (EBS) is a rare genetic condition typified by superficial bullous lesions following incident frictional trauma to the skin. Most cases of EBS are due to dominantly-acting mutations in keratin 14 (K14) or K5, the type I and II intermediate filament (IF) proteins that co-polymerize to form a pan-cytoplasmic network of 10nm filaments in basal keratinocytes of epidermis and related epithelia. Defects in K5–K14 filament network architecture cause basal keratinocytes to become fragile, and account for their rupture upon exposure to mechanical trauma. The discovery of the etiology and pathophysiology of EBS was intimately linked to the quest for an understanding of the properties and function of keratin filaments in skin epithelia. Since then, continued cross-fertilization between basic science efforts and clinical endeavors has highlighted several additional functional roles for keratin proteins in the skin, suggested new avenues for effective therapies for keratin-based diseases, and expanded our understanding of the remarkable properties of skin as an organ system. Discovery of the genetic basis for the inherited bullous disease Epidermolysis Bullosa Simplex (EBS), made twenty years ago, provided a new and paradigm-shifting blueprint fo

  • A Function for Keratins and aCommon Thread among Different Types of Epidermolysis Bullosa Simplex Diseases
    2013
    Co-Authors: Pierre A Coulombe, Elizabeth M Hutton, Robert Vassar, Elaine Fuchs
    Abstract:

    Abstract. Previously we demonstrated that transgenic mice expressing a mutant keratin in the basal layer of their stratified squamous epithelia exhibited a phenotype bearing resemblance to a subclass (Dowling Meara) of a heterogeneous group of human skin disorders known as Epidermolysis Bullosa Simplex (EBS

  • defining keratin protein function in skin epithelia Epidermolysis Bullosa Simplex and its aftermath
    Journal of Investigative Dermatology, 2012
    Co-Authors: Pierre A Coulombe
    Abstract:

    Epidermolysis Bullosa Simplex (EBS) is a rare genetic condition typified by superficial bullous lesions following incident frictional trauma to the skin. Most cases of EBS are due to dominantly acting mutations in keratin 14 (K14) or K5, the type I and II intermediate filament (IF) proteins that copolymerize to form a pancytoplasmic network of 10nm filaments in basal keratinocytes of epidermis and related epithelia. Defects in K5–K14 filament network architecture cause basal keratinocytes to become fragile, and account for their rupture upon exposure to mechanical trauma. The discovery of the etiology and pathophysiology of EBS was intimately linked to the quest for an understanding of the properties and function of keratin filaments in skin epithelia. Since then, continued cross-fertilization between basic science efforts and clinical endeavors has highlighted several additional functional roles for keratin proteins in the skin, suggested new avenues for effective therapies for keratin-based diseases, and expanded our understanding of the remarkable properties of the skin as an organ system.

  • reprogramming of keratin biosynthesis by sulforaphane restores skin integrity in Epidermolysis Bullosa Simplex
    Proceedings of the National Academy of Sciences of the United States of America, 2007
    Co-Authors: Michelle L Kerns, Daryle Depianto, Albena T Dinkovakostova, Paul Talalay, Pierre A Coulombe
    Abstract:

    Epidermolysis Bullosa Simplex (EBS) is a rare inherited condition in which the epidermis loses its integrity after mechanical trauma. EBS is typified by the dysfunction of intermediate filaments in basal keratinocytes of epidermis. Most cases of EBS are due to mutations in the keratin 5 or 14 gene (K5 and K14), whose products copolymerize to form intermediate filaments in basal keratinocytes. Available treatments for this disorder are only palliative. Here we exploit functional redundancy within the keratin gene family as the basis for therapy. We show that genetic activation of Gli2 or treatment with a pharmacological activator of Nrf2, two transcription factors eliciting distinct transcriptional programs, alleviates the blistering caused by a K14 deficiency in an EBS mouse model, correlating with K17 induction in basal epidermal keratinocytes. Nrf2 induction is brought about by treatment with sulforaphane, a natural product. Sulforaphane thus represents an attractive option for the prevention of skin blistering associated with K14 mutations in EBS.

K Stephens - One of the best experts on this subject based on the ideXlab platform.

  • expression of a truncated keratin 5 may contribute to severe palmar plantar hyperkeratosis in Epidermolysis Bullosa Simplex patients
    Journal of Investigative Dermatology, 2001
    Co-Authors: Robert J Livingston, Lynne T Smith, Virginia P Sybert, Beverly A Dale, Richard B Presland, K Stephens
    Abstract:

    Epidermolysis Bullosa Simplex are dominant disorders of skin fragility characterized by intraepidermal blistering upon mild mechanical trauma. Skin fragility is caused by expression of either an abnormal keratin 5 or an abnormal keratin 14 protein, which compromises the structure and function of the keratin cytoskeleton of basal cells. We report an Epidermolysis Bullosa Simplex patient with a novel single base substitution (A→T1414) that changes the lysine residue at amino acid 472 to a non-sense codon (K472X). This change predicts the synthesis of a truncated keratin 5, missing 119 amino acids, including the entire tail domain and the highly conserved KLLEGE motif at the carboxy terminus of the 2B domain of the central rod. Expression of an altered keratin 5, of predicted mass and pI for the product of the K472X allele, was documented by one- and two-dimensional western blots of protein extracts from patient skin. Ultrastructural analysis of the patient's nonhyperkeratotic skin was remarkable for basal keratinocytes with dense and irregular keratin filaments proximal to the basement membrane. Keratinocytes, transfected with a cDNA carrying the A→T1414 non-sense mutation, overexpressed a truncated keratin 5, and showed a disorganized and collapsed keratin filament cytoskeleton. This is the second Epidermolysis Bullosa Simplex patient reported with a premature termination mutation in the KLLEGE motif. The remarkable occurrence of severe palmar–plantar hyperkeratosis in both patients suggests that the keratin 5 tail domain may have unrecognized, but important, normal functions in palmar–plantar tissues.

  • a common keratin 5 gene mutation in Epidermolysis Bullosa Simplex weber cockayne
    Journal of Investigative Dermatology, 1995
    Co-Authors: Pamela Ehrlich, Virginia P Sybert, Anne Spencer, K Stephens
    Abstract:

    The Weber-Cockayne subtype of Epidermolysis Bullosa Simplex is an inherited skin-fragility disorder characterized by basal keratinocyte lysis and epidermal blistering confined primarily to the hands and feet. The disorder results from a mutation in either the keratin 5 or keratin 14 gene, which encode the peptide components of the obligate heterodimeric keratin intermediate filaments of the basal cell. We have determined that a T → G substitution mutation in keratin 5, which results in a Ile → Ser change codon 161, is common among patients with the Weber-Cockayne disease variant, accounting for six of 13 cases tested. The observed high frequency of this mutation may result from either a mutational hot spot or a founder effect, The potential utility of this common mutation in confirming disease status in some at-risk individual is discussed.

  • a keratin 14 mutational hot spot for Epidermolysis Bullosa Simplex dowling meara implications for diagnosis
    Journal of Investigative Dermatology, 1993
    Co-Authors: K Stephens, Pamela Ehrlich, Virginia P Sybert, Ellen M Wijsman, Anne Spencer
    Abstract:

    Abstract Recently, two patients with the Dowling-Meara subtype of Epidermolysis Bullosa Simplex (EBS-DM) were reported with different mutations in codon 125 of the keratin 14 gene. To determine whether these are common mutations, we screened ten EBS-DM patients and their families using single nucleotide primer extension. Four of ten unrelated EBS-DM patients had a G→-A substitution at base pair 434 of codon 125, whereas one case out of ten had a C→-T substitution at position 433 of the same codon. The G434A alteration cosegregated with the disorder in two multigenerational families; no recombination events were detected. In these two families, linkage analysis provided significant evidence in favor of linkage between G434A and the EBS-DM phenotype, with a LOD score of 3.29 at a recombination rate of 0%. Codon 125 substitutions identified in three unrelated sporadic EBS-DM patients were not found in their clinically unaffected parents. Together, these data provide compelling genetic evidence that the codon 125 substitutions are causal for EBS-DM. The high frequency of mutation at this site in individuals with EBS-DM now makes DNA-based diagnosis of this disorder feasible.

Virginia P Sybert - One of the best experts on this subject based on the ideXlab platform.

  • expression of a truncated keratin 5 may contribute to severe palmar plantar hyperkeratosis in Epidermolysis Bullosa Simplex patients
    Journal of Investigative Dermatology, 2001
    Co-Authors: Robert J Livingston, Lynne T Smith, Virginia P Sybert, Beverly A Dale, Richard B Presland, K Stephens
    Abstract:

    Epidermolysis Bullosa Simplex are dominant disorders of skin fragility characterized by intraepidermal blistering upon mild mechanical trauma. Skin fragility is caused by expression of either an abnormal keratin 5 or an abnormal keratin 14 protein, which compromises the structure and function of the keratin cytoskeleton of basal cells. We report an Epidermolysis Bullosa Simplex patient with a novel single base substitution (A→T1414) that changes the lysine residue at amino acid 472 to a non-sense codon (K472X). This change predicts the synthesis of a truncated keratin 5, missing 119 amino acids, including the entire tail domain and the highly conserved KLLEGE motif at the carboxy terminus of the 2B domain of the central rod. Expression of an altered keratin 5, of predicted mass and pI for the product of the K472X allele, was documented by one- and two-dimensional western blots of protein extracts from patient skin. Ultrastructural analysis of the patient's nonhyperkeratotic skin was remarkable for basal keratinocytes with dense and irregular keratin filaments proximal to the basement membrane. Keratinocytes, transfected with a cDNA carrying the A→T1414 non-sense mutation, overexpressed a truncated keratin 5, and showed a disorganized and collapsed keratin filament cytoskeleton. This is the second Epidermolysis Bullosa Simplex patient reported with a premature termination mutation in the KLLEGE motif. The remarkable occurrence of severe palmar–plantar hyperkeratosis in both patients suggests that the keratin 5 tail domain may have unrecognized, but important, normal functions in palmar–plantar tissues.

  • a common keratin 5 gene mutation in Epidermolysis Bullosa Simplex weber cockayne
    Journal of Investigative Dermatology, 1995
    Co-Authors: Pamela Ehrlich, Virginia P Sybert, Anne Spencer, K Stephens
    Abstract:

    The Weber-Cockayne subtype of Epidermolysis Bullosa Simplex is an inherited skin-fragility disorder characterized by basal keratinocyte lysis and epidermal blistering confined primarily to the hands and feet. The disorder results from a mutation in either the keratin 5 or keratin 14 gene, which encode the peptide components of the obligate heterodimeric keratin intermediate filaments of the basal cell. We have determined that a T → G substitution mutation in keratin 5, which results in a Ile → Ser change codon 161, is common among patients with the Weber-Cockayne disease variant, accounting for six of 13 cases tested. The observed high frequency of this mutation may result from either a mutational hot spot or a founder effect, The potential utility of this common mutation in confirming disease status in some at-risk individual is discussed.

  • a keratin 14 mutational hot spot for Epidermolysis Bullosa Simplex dowling meara implications for diagnosis
    Journal of Investigative Dermatology, 1993
    Co-Authors: K Stephens, Pamela Ehrlich, Virginia P Sybert, Ellen M Wijsman, Anne Spencer
    Abstract:

    Abstract Recently, two patients with the Dowling-Meara subtype of Epidermolysis Bullosa Simplex (EBS-DM) were reported with different mutations in codon 125 of the keratin 14 gene. To determine whether these are common mutations, we screened ten EBS-DM patients and their families using single nucleotide primer extension. Four of ten unrelated EBS-DM patients had a G→-A substitution at base pair 434 of codon 125, whereas one case out of ten had a C→-T substitution at position 433 of the same codon. The G434A alteration cosegregated with the disorder in two multigenerational families; no recombination events were detected. In these two families, linkage analysis provided significant evidence in favor of linkage between G434A and the EBS-DM phenotype, with a LOD score of 3.29 at a recombination rate of 0%. Codon 125 substitutions identified in three unrelated sporadic EBS-DM patients were not found in their clinically unaffected parents. Together, these data provide compelling genetic evidence that the codon 125 substitutions are causal for EBS-DM. The high frequency of mutation at this site in individuals with EBS-DM now makes DNA-based diagnosis of this disorder feasible.

Dedee F Murrell - One of the best experts on this subject based on the ideXlab platform.

  • A Review of 52 Pedigrees with Epidermolysis Bullosa Simplex Identifying Ten Novel Mutations in KRT5 and KRT14 in Australia
    Society for Publication of Acta Dermato-Venereologica, 2017
    Co-Authors: Emma N. Kim, Adam G. Harris, Linda J. Bingham, Wenfei Yan, Dedee F Murrell
    Abstract:

    Epidermolysis Bullosa Simplex (EBS) is a rare heritable skin fragility disorder, most commonly caused by dominant mutations in KRT5 and KRT14. EBS shows clinical heterogeneity with localised, intermediate and generalised severe forms, which tend to correlate with the location and nature of the disease causing mutations. We therefore aimed to identify the KRT5 and KRT14 mutations in patients diagnosed with EBS in Australia, and explore in depth the genotype to the phenotype correlations in patients with novel variants. Australian patients who were diagnosed with EBS after referral to the Australian National Diagnostic Laboratory for EB were offered mutation screening in the KRT5 and KRT14 genes. From this, 32 different mutations in KRT5 and KRT14 were identified within 39 of 52 pedigrees. Ten of these mutations from 9 different pedigrees were novel, a further fatal case caused by KRT5 E477K is reported and in addition the third reported case of digenic inheritance in EBS was also observed

  • Epidermolysis Bullosa Simplex dowling meara due to an arginine to cysteine substitution in exon 1 of keratin 14
    Australasian Journal of Dermatology, 2002
    Co-Authors: Champi Premaratne, S Klingberg, Ian A Glass, Kellie Wright, Dedee F Murrell
    Abstract:

    Epidermolysis Bullosa Simplex (EBS) is a blistering disorder affecting the basal layer of the epidermis usually inherited in an autosomal dominant fashion. Most cases are caused by mutations in the genes encoding keratin 5 (K5) and keratin 14 (K14) and are characterized by cytolysis within the basal layer of the epidermis. We report a patient manifesting the Dowling-Meara variant of EBS in whom we characterized a cytosine to thymine transition at codon 125 (R125C) in K14. This missense mutation is located at the amino terminus of the helical rod domain of the keratin 14 molecule, resulting in defective pairing with K5, thereby disrupting keratin tonofibril integrity.

  • keratin 14 point mutations at codon 119 of helix 1a resulting in different Epidermolysis Bullosa Simplex phenotypes
    Journal of Investigative Dermatology, 2001
    Co-Authors: Rebecca E Cummins, S Klingberg, Dedee F Murrell, Julie Wesley, Maureen Rogers, Yali Zhao
    Abstract:

    Epidermolysis Bullosa Simplex is a heterogeneous group of inherited bullous disorders due to mutations in keratins 5 and 14. We report two different mutations in keratin 14 at codon 119 of the helix initiation peptide, each with different phenotypic expression. One, a sporadic case that clinically resembles Dowling-Meara Epidermolysis Bullosa Simplex, resulted from conversion of methionine to threonine (M119T). The other, a multigeneration family with the Koebner phenotype, resulted from a previously unreported methionine to valine substitution (M119V). We suggest that loss of hydrophobicity during conversion of methionine to threonine is responsible for the more severe presentation of the first family, whereas maintenance of the hydrophobic nature of the amino acid with conversion to valine resulted in a less severe variant of Epidermolysis Bullosa Simplex. Although most prior mutations in the highly conserved boundary motif of the α-helix have resulted in the Dowling-Meara subtype, our findings confirm that it is not always possible to predict the Epidermolysis Bullosa Simplex severity on the basis of the location of the mutation along the keratin polypeptide. The specific amino acid substitution may be more critical in some cases.