Diagnosis Of Epidermolysis Bullosa Simplex Research Articles

Whole exome sequencing in a sample of Peruvian patients diagnosed with epidermolysis bullosa.

Epidermolysis bullosa (EB) is a complex and heterogeneous dermatological disease. Four main types of EB have been described, each of them with distinct characteristics: EB simplex (EBS), dystrophic EB (DEB), junctional EB (JEB) and Kindler EB (KEB). Each main type varies in its manifestations, severity, and genetic abnormality. We sought mutations in 19 genes known to cause EB and 10 genes associated with other dermatologic diseases in 35 Peruvian pediatric patients of a rich Amerindian genetic background. Whole exome sequencing and bioinformatics analysis was performed. Thirty-four of 35 families revealed an EB mutation. Dystrophic EB was the most frequently diagnosed type, with 19 (56%) patients, followed by EBS (35%), JEB (6%), and KEB (3%). We found 37 mutations in seven genes; 27 (73%) were missense mutations; 22 (59%) were novel mutations. Five cases changed their initial diagnosis of EBS. Four were reclassified as DEB and one as JEB. Inspection into other non-EB genes revealed a variant, c.7130C>A, in the gene FLGR2, which was present in 31 of the 34 patients (91%). We were able to confirm and identify pathological mutations in 34 of 35 patients.

488 Ground reaction forces(GRF) in patients with epidermolysis bullosa simplex(EBS) during walking

In EBS mutations in proteins encoding KRT5 & KRT14 result in abnormalities affecting the structural stability of basal keratinocytes. This causes blisters and keratoderma on the hands and feet which cause significant pain and difficulty walking. However, the impact on gait has not yet been studied. We aimed to study how people with EBS walk, and if they adopt any strategy to modify the distribution of forces under their feet. Adults with a diagnosis of EBS were asked to walk barefoot at a spontaneous speed.

Immunofluorescence mapping, electron microscopy and genetics in the diagnosis and sub-classification of inherited epidermolysis bullosa: a single-centre retrospective comparative study of 87 cases with long-term follow-up.

Epidermolysis bullosa (EB) comprises a heterogeneous group of skin fragility disorders, classified in four major types based on skin cleavage level, i.e. EB simplex (EBS), junctional EB (JEB), dystrophic EB (DEB), Kindler EB, and in more than 30 subtypes defined by the combination of laboratory and clinical data, including disease course. Our aims were to address whether, in the age of genomics, electron microscopy (TEM) has still a role in diagnosing EB, and whether the genotype per se may be sufficient to sub-classify EB. A thoroughly characterized single-centre EB case series was retrospectively evaluated to compare the power of TEM with immunofluorescence mapping (IFM) in establishing the EB type, and the ability of TEM, IFM and genetics to predict selected EB subtypes, i.e. severe dominant EBS (DEBS), severe JEB, severe recessive DEB (RDEB) and DEB self-improving, using genetic and final diagnosis, respectively, as gold standard. The series consisted of 87 patients, including 44 newborns, with a median follow-up of 54months. Ninety-five mutations were identified in EB-associated genes, including 25 novel variants. Both IFM and TEM were diagnostic in about all cases of JEB (21/21 for both) and DEB (43/44 for IFM, 44/44 for TEM). TEM sensitivity was superior to IFM for EBS (19/20 vs. 16/19). As to EB subtyping, IFM performed better than genetics in identifying severe JEB cases due to laminin-332 defect (14/14 vs. 10/14) and severe RDEB (eight/nine vs. seven/nine). Genetics had no role in self-improving DEB diagnosis; it almost equalled TEM in predicting severe DEBS (eight/nine vs. nine/nine) and enabled to discriminate dominant from recessive non-severe DEB phenotypes and to identify special subtypes, e.g. DEBS with KLHL24 mutations. Transmission electron microscopy remains relevant to the diagnosis of EBS. IFM and genetics are essential and complementary tools in the vast majority of EB cases.

Bullous diseases caused by KRT1 gene mutations: from epidermolytic hyperkeratosis to a novel variant of epidermolysis bullosa simplex.

IntroductionMutations in the KRT1 gene encoding keratin 1 cause epidermolytic hyperkeratosis characterized by blistering in the neonatal period followed by ichthyotic hyperkeratosis in childhood and adolescent life. We observed a spectrum of clinical manifestations of blistering disorders caused by different mutations in the same KRT1 gene.AimTo analyse the phenotypic spectrum of blistering disorders caused by the KRT1 mutations.Material and methodsFour patients with an epidermal barrier defect manifesting as blistering with the KRT1 mutations were included to the study. The clinical course of the disease was analysed, histology, immunofluorescence and electron microscopic examinations were performed.ResultsAn adult patient with severe ichthyosis with p.Asn188Lys mutation in exon 1 of KRT1 who occasionally develops blisters in adolescence represents epidermolytic hyperkeratosis, a newborn child who died 4 days after birth due to disruption of the epidermal barrier (extensive blister and erosions) with mutation p.Ser193Pro in the KTR1 gene and two adult sisters harbouring heterozygous mutation c.591+1A>G in the KRT1 gene who present superficial blisters induced by mild trauma from the birth up to adolescent life without ichthyosis suggesting the diagnosis of epidermolysis bullosa simplex. Histopathology in all adult patients showed cytoplasm disruption in keratinocytes of the stratum spinosum with keratohyalin granule-like structures and, on the ultrastructural level, the presence of keratin clumping confirming the pathology of keratin intermediate filaments.ConclusionsThis study extends the knowledge of the clinical spectrum for the KRT1 gene mutations. This is the first description of familial dominant epidermolysis bullosa simplex linked to the KRT1 mutation.

Novel keratin 5 mutation in a family with epidermolysis bullosa simplex.

The aim of the present study was to identify the causative gene defects associated with epidermolysis bullosa simplex (EBS) in a pedigree. The diagnosis of EBS was confirmed in two patients from that pedigree based on the clinical manifestations, histopathological examination of the skin and family history. Blood samples were collected from 6 family members and 100 heathy controls, and genomic DNA and RNA were extracted. Mutation analysis of the keratin 5 gene (KRT5) was conducted using polymerase chain reaction (PCR) direct sequencing and PCR-restriction fragment length polymorphism. In the pedigree, the results of PCR direct sequencing revealed a heterozygous missense mutation in codon 202 of exon 2 of KRT5 (c.605T>A), which led to an amino acid change (p.L202Q) in the patients with EBS but was absent from the unaffected family members and 100 population controls. In conclusion, a novel missense mutation in the KRT5 gene was identified that had a pathogenic role in EBS in the population studied, which enriches the germline mutation spectrum of the KRT5 gene.

Clinical heterogeneity in recessive epidermolysis bullosa due to mutations in the keratin 14 gene, KRT14

Epidermolysis bullosa simplex (EBS), the most common subtype of EB, is usually inherited as an autosomal dominant trait caused by mutations in either the keratin 5 (KRT5) or keratin 14 (KRT14) genes. Recessive EBS (R-EBS) is extremely rare. We present the first Australian patient diagnosed with R-EBS, to our knowledge, and a comprehensive review of genotypes and phenotypes of R-EBS reported cases. The female proband, of Turkish descent with consanguineous parentage, was referred to us at the age of 8 years. Clinically, she had a severe phenotype including generalized blisters, mucosal involvement and EB naevi. Immunofluorescence mapping and electron microscopy were consistent with a diagnosis of EBS. Staining for Keratin 14 (K14) was negative. The basal layer, however, reacted with monoclonal antibodies to keratins 6 (K6) and 16 (K16). Mutation screening from genomic DNA showed that the proband was homozygous for the truncation mutation Y204X in exon 3 of KRT14, and both unaffected parents were heterozygous for a single KRT14 Y204X mutation. The phenotype of our patient is reported in more detail and with longer follow-up than those of others published in the literature. The proband's phenotype was severe as an infant but improved with age, suggesting that an alternative keratin is pairing with K5 in her skin to compensate for the loss of K14--a novel biological compensatory mechanism. It is interesting that K6 and K16 were expressed, as these are normally positive in hyperproliferative skin disorders.

Kindler Syndrome

Kindler syndrome (KS) is a rare genetic disorder that is characterized by blistering in infancy, followed by the onset of poikiloderma and photosensitivity in childhood. The recently elucidated molecular pathogenesis involves mutations in KIND1, a gene encoding the protein kindlin-1, which is involved in the attachment of the actin cytoskeleton to the extracellular matrix in basal keratinocytes. We describe a child with the neonatal diagnosis of epidermolysis bullosa simplex who developed poikiloderma and skin fragility at 6 years of age. His skin showed diminished staining with anti-kindlin-1 antibody, and genetic analysis revealed that he was a compound heterozygote with a previously unreported mutation in KIND1. Ultrastructural clues to the diagnosis of KS were present in a biopsy specimen that was obtained when the patient was 10 months old, before he developed poikiloderma and photosensitivity. In this case, a combination of a known mutation (R271X) and a newly described mutation (1755delT) in the KIND1 gene produced loss of function in kindlin-1, leading to the clinical features of KS. Ultrastructural findings characteristic of KS were evident years before the onset of poikiloderma and sun sensitivity. In infancy, electron microscopy can enable early, accurate diagnosis of KS.

Epidermolysis Bullosa Simplex: Recurrent and De Novo Mutations in the KRT5 and KRT14 Genes, Phenotype/Genotype Correlations, and Implications for Genetic Counseling and Prenatal Diagnosis

Epidermolysis bullosa simplex (EBS) is a mechano-bullous disorder characterized by intraepidermal blistering within the basal keratinocytes as a result of trauma to the skin. As part of the DNA diagnostics program, our laboratory has analyzed a cohort of 57 patients with the initial referral diagnosis of EBS. Among these patients, 18 were found to harbor heterozygous mutations in the keratin 5 or keratin 14 genes, KRT5 and KRT14, respectively, whereas in 14 cases, the disease was associated with mutations in both alleles of the plectin gene. Among the keratin mutations, 12 were distinct and six were novel, and in most cases there was no family history of a blistering disease. Prenatal diagnosis of eight pregnancies with keratin gene mutations, at risk for EBS either because one of the parents was affected (three cases) or history of a previously affected child as a result of a de novo mutation (five cases), predicted two fetuses being affected and six being normal. No recurrence of the de novo mutations in these pregnancies was disclosed. Collectively, the data suggest that a significant number of cases diagnosed as EBS are due to plectin mutations, and many cases result from de novo mutations in KRT5 and KRT14 genes. These findings have implications for genetic counseling and prenatal diagnosis for EBS.

Epidermolysis Bullosa Simplex Associated with Pyloric Atresia Is a Novel Clinical Subtype Caused by Mutations in the Plectin Gene ( PLEC1)

Epidermolysis bullosa (EB) is an inherited mechano-bullous disorder of the skin, and is divided into three major categories: EB simplex (EBS), dystrophic EB, and junctional EB (JEB). Mutations in the plectin gene (PLEC1) cause EBS associated with muscular dystrophy, whereas JEB associated with pyloric atresia (PA) results from mutations in the alpha6 and beta4 integrin genes. In this study, we examined three EB patients associated with PA from two distinct families. Electron microscopy detected blister formation within the basal keratinocytes leading to the diagnosis of EBS. Surprisingly, immunohistochemical studies using monoclonal antibodies to a range of basement membrane proteins showed that the expression of plectin was absent or markedly attenuated. Sequence analysis demonstrated four novel PLEC1 mutations. One proband was a compound heterozygote for a nonsense mutation of Q305X and a splice-site mutation of 1344G-->A. An exon-trapping experiment suggested that the splice-site mutation induced aberrant splicing of the gene. The second proband harbored a heterozygous maternal nonsense mutation, Q2538X and homozygous nonsense mutations R1189X. Analysis of the intragenic polymorphisms of PLEC1 suggested that R1189X mutations were due to paternal segmental uniparental isodisomy. These results indicate that PLEC1 is a possible causative gene in this clinical subtype, EBS associated with PA. Furthermore, two patients out of our three cases died in infancy. In terms of clinical prognosis, this novel subtype is the lethal variant in the EBS category.

Plectin deficient epidermolysis bullosa simplex with 27-year-history of muscular dystrophy

Epidermolysis bullosa simplex associated with muscular dystrophy is caused by plectin deficiency. To report clinical, immunohistochemical, ultrastructural and molecular features of a 52-year-old Japanese patient affected with this disease, whose muscular disease had been followed-up for 27 years. We performed histopathological study, immunofluorescence, electron microscopic study and mutation detection analysis for plectin. The patient developed blisters and erosions followed by nail deformity on the traumatized regions from birth. The skin lesions were continuously developed to date. The histopathological study showed subepidermal blister. Electron microscopic study showed blister formation inside the basal cells at the level just above the attachment plaque of hemidesmosome. Immunofluorescence showed complete loss of staining to plectin. The mutation analysis using protein truncation test and DNA sequencing revealed a C-to-T transition at nucleotide position 7006 of the plectin cDNA sequence, which lead a novel homozygous nonsense mutation (R2319X). From the above results, the diagnosis of epidermolysis bullosa simplex associated with muscular dystrophy was made. Slight muscular dystrophy was noticed at the age of 25 years. The muscular dystrophy gradually progressed and she could not walk at the age of 46 years. However, she can still breathe and swallow by herself. This is the patient of this disease with the longest follow-up, and may indicate the slow progress of muscular condition of this disease.

Genetic Diagnosis of Epidermolysis Bullosa Simplex in the Department of Dermatology, Kurume University School of Medicine

Genetic Diagnosis of Epidermolysis Bullosa Simplex in the Department of Dermatology, Kurume University School of Medicine

Immunohistochemical detection of keratin with the monoclonal antibody MNF116 is useful in the diagnosis of epidermolysis bullosa simplex.

Epidermolysis bullosa simplex (EBS) is an uncommon genetic skin disease characterized by fragility of the basal keratinocytes and propensity to develop blisters. While a panel of antibodies against type IV collagen, laminin, and bullous pemphigoid antigen has been used to identify cases of EBS in frozen sections, we have found that a monoclonal antibody detecting cytokeratin in basal keratinocytes is useful in paraffin sections. Formalin-fixed, paraffin-embedded tissues from 12 patients with EBS were studied with the following monoclonal antibodies: MNF116 (DAKO, Carpinteria, CA), CAM 5.2 (Becton Dickinson, San Jose, CA), and AE1-AE3 mixture (Boehringer Mannheim Corp, Indianapolis, IN). Histologically, all the cases had focal vacuolization of the basal cell layer, with areas of dermal-epidermal separation. MNF116 was strongly positive in the basal keratinocytes, including the vacuolated ones, and demonstrated the presence of fragments of keratinocytes attached to the floor of the blister. CAM 5.2 stained sweat ducts only. AE1-AE3 was weakly positive in the basal cells, and almost completely negative on the fragmented basal cell keratinocytes. We consider that the immunostain with MNF116 in tissues fixed routinely in formalin and embedded in paraffin is helpful for the direct demonstration of the level of splitting in EBS.

Severe Infantile Epidermolysis Bullosa Simplex

We encountered eight patients with epidermolysis bullosa (EB) simplex of the Dowling-Meara type, who presented in infancy with severe blistering and were originally clinically thought to have recessive dystrophic EB. One infant died in the neonatal period, and the others have had reduced blistering with advancing age. However, in two of the three older patients, the development of severe disabling hyperkeratosis of the palms and soles has been a prominent feature. The correct diagnosis of EB simplex was initially not made in five patients, because, on routine histologic examination, the blister was apparently subepidermal. Electron microscopy confirmed the correct diagnosis of EB simplex by demonstration of basal cell cytolysis. There was clumping of tonofilaments in seven patients. Immunofluorescence demonstrated a cleft above the basal layer in three cases. The findings of severe extensive blistering at birth that improves with age, milia formation, acral distribution with herpetiform groups of blisters in older children, intraoral lesions, absence of scarring, and intraepidermal clefting due to basal cell cytolysis and clumping of tonofilaments within these basal cells as seen on electron microscopic examination present a subtype of EB simplex similar to that described by Dowling and Meara. This has been recognized in the European but not in the American literature and is probably more frequent than has been previously reported.