Next-generation sequencing through multigene panel testing for the diagnosis of hereditary epidermolysis bullosa in Chinese population.

Epidermolysis bullosa (EB) is a heritable blistering disorder. We performed a next-generation sequencing-based multigene panel test and successfully predicted 100% of the EB types, including, 36 EB simplex (EBS), 13 junctional EB (JEB), 86 dystrophic EB (DEB), and 3 Kindler EB. Chinese JEB and recessive DEB (RDEB) patients have relatively mild phenotypes; for severe type separately accounts for 45.5% and 23.8%, respectively. We identified 96 novel and 49 recurrent pathogenic variants in 11 genes, although we failed to detect the second mutation in one JEB and five RDEB patients. We identified one novel p.E475K mosaic mutation in the clinically normal mother of one out of 13 EBS patients with KRT5 mutations, one recurrent p.G2034R mosaic mutation, and one novel p.G2043R mosaic mutation in the clinically normal relatives of two out of 19 dominant DEB patients. This study shows that next-generation technology could be an effective tool in diagnosing EB.

The Role of Collagen IV and Cytokeratin 5/6 Immunohistochemistry in Identifying Subtypes of Hereditary Epidermolysis Bullosa.

Hereditary epidermolysis bullosa (EB) constitute a genodermatosis group with variable clinical severity. Biopsies diagnosed as EB in the last 4 years were retrieved from the database of the king Khalid University Hospital and military hospital lab at Saudi Arabia. The current study was performed to examine the diagnostic usefulness of immunohistochemistry, as compared with electron microscopic examination, for subclassification of HEB. Fourteen cases were studied. Collagen IV immunostain was located above the blister in all dystrophic EB cases, and below the blister in all cases of epidermolytic and junctional EB. Cytokeratin 5/6 was visible above the blister in all cases of dystrophic and junctional types EB. In 2 out of 4 cases of epidermolytic EB, cytokeratin 5/6 was seen only above the cleft, whereas 1 case revealed positivity above and below the blister. One epidermolytic EB case showed scattered fragments of keratinocytes inside the blister.

Inherited epidermolysis bullosa: new diagnostic criteria and classification.

Epidermolysis bullosa (EB) is a group of inherited, mechanobullous disorders caused by mutations in various structural proteins in the skin. There have been several advances in the classification of EB since it was first introduced in the late 19th century. We now recognize four major types of EB, depending on the location of the target proteins and level of the blisters: EB simplex (epidermolytic), junctional EB (lucidolytic), dystrophic EB (dermolytic), and Kindler syndrome (mixed levels of blistering). This contribution will summarize the most recent classification and discuss the molecular basis, target genes, and proteins involved. We have also included new subtypes, such as autosomal dominant junctional EB and autosomal recessive EB due to mutations in the dystonin (DST) gene, which encodes the epithelial isoform of bullouspemphigoid antigen 1. The main laboratory diagnostic techniques-immunofluorescence mapping, transmission electron microscopy, and mutation analysis-will also be discussed. Finally, the clinical characteristics of the different major EB types and subtypes will be reviewed.

Categorizing immunoflourescence mapping in epidermolysis bullosa with pyloric atresia: Use as a broad prognostic indicator.

Epidermolysis bullosa with pyloric atresia is a form of junctional epidermolysis bullosa associated with gastrointestinal abnormalities, which may include pyloric atresia. Genotype phenotype correlation is poorly understood and prognosis is difficult, if not impossible, to predict. Immunoflourescence mapping is an ideal candidate for developing a broad prognostic indicator for epidermolysis bullosa with pyloric atresia without the need for genetic mutation analysis. However, the tool developed in this paper does have limitations due to the small number of cases available and the effects of deleterious mutations in highly conserved cysteine residues on the predicted length of survival.

Genetic abnormalities and clinical classification of epidermolysis bullosa.

Genetic abnormalities for different subtypes of epidermolysis bullosa (EB) have been described. In dominant simplex type EB, mutations of the K5 or K14 gene lead to disruption of basal cells and the formation of bullae. The recessive simplex types include EB with muscular dystrophy due to abnormal plectin, EB without muscular dystrophy in patients homozygous for K14 gene abnormalities, and skin fragility syndrome, with formation of acantholytic vesicles within the epidermis due to PKP1 gene mutations. In junctional EB, mutations of the laminin 5, type XVII collagen, and alpha 6 beta 4 integrin genes have been reported. Dystrophic type EB is associated with various abnormalities of the type VII collagen gene. A new classification of EB based on these genetic abnormalities has been proposed. However, some concern has been voiced regarding the clinical utility of a classification based solely on genetic abnormalities. Although the reasons are unclear, identical genetic abnormalities have been known to be associated with different clinical features. A classification including a component based on clinical features would therefore be preferable. This article describes recently discovered genetic abnormalities and offers a new classification scheme for EB.

Laminin 5 mutations in junctional epidermolysis bullosa: molecular basis of Herlitz vs. non-Herlitz phenotypes.

Junctional epidermolysis bullosa (JEB) is a group of heritable blistering diseases in which tissue separation occurs within the lamina lucida of the cutaneous basement membrane zone. Clinically, two broad subcategories have been recognized: The Herlitz variant (H-JEB; OMIM 226700) is characterized by early demise of the affected individuals, usually within the first year of life, while non-Herlitz (nH-JEB; OMIM 226650) patients show a milder phenotype with life-long blistering, yet with normal lifespan. In this study, we have examined a cohort of 27 families, 15 with Herlitz and 12 with non-Herlitz JEB, for mutations in the candidate genes, LAMA3, LAMB3, and LAMC2, encoding the subunit polypeptides of laminin 5. The mutation detection strategy consisted of PCR amplification of all exons in these genes, followed by heteroduplex scanning and nucleotide sequencing. We were able to identify pathogenic mutations in both alleles of each proband, the majority of the mutations being in the LAMB3 gene. Examination of the mutation database revealed that most cases with Herlitz JEB harbored premature termination codon (PTC) mutations in both alleles. In non-Herlitz cases, the PTC mutation was frequently associated with a missense mutation or a putative splicing mutation in trans. In three cases with putative splicing mutations, RT-PCR analysis revealed a repertoire of splice variants in-frame, predicting the synthesis of either shortened or lengthened, yet partly functional, polypeptides. These observations would explain the relatively mild phenotype in cases with splicing mutations. Collectively, these findings, together with the global laminin 5 mutation database, contribute to our understanding of the genotype/phenotype correlations explaining the Herlitz vs non-Herlitz phenotypes.

[Syndromes 13. Epidermolysis bullosa]. / Syndromen 13. Epidermolysis bullosa.

Epidermolysis Bullosa is characterised by blister formation of skin and mucous membranes. Three major varieties of epidermolysis bullosa (EB) are reviewed including their dental and oral aspects: EB simplex, junctional EB and dystrophic EB. Marked oral involvement of the soft and hard tissues can produce potentially devastating alterations in anatomy and function. Oral debilitation is limited primarily to the recessive dystrophic EB type due to soft tissue scarring following blister formation. Microstomia, ankyloglossia and obliteration of the oral vestibule are typical features of dystrophic EB. In other cases enamel hypoplasia and cementum disorders can be present. Epidermolysis bullosa has considerable impact on oral health and dental care.

Extent of laminin-5 assembly and secretion effect junctional epidermolysis bullosa phenotype.

Junctional epidermolysis bullosa (JEB) is an autosomal recessive skin blistering disease with both lethal and nonlethal forms, with most patients shown to have defects in laminin-5. We analyzed the location of mutations, gene expression levels, and protein chain assembly of the laminin-5 heterotrimer in six JEB patients to determine how the type of genetic lesion influences the pathophysiology of JEB. Mutations within laminin-5 genes were diversely located, with the most severe forms of JEB correlating best with premature termination codons, rather than mapping to any particular protein domain. In all six JEB patients, the laminin-5 assembly intermediates we observed were as predicted by our previous work indicating that the alpha3beta3gamma2 heterotrimer assembles intracellularly via a beta3gamma2 heterodimer intermediate. Since assembly precedes secretion, mutations that disrupt protein-protein interactions needed for assembly are predicted to limit the secretion of laminin-5, and likely to interfere with function. However, our data indicate that typically the most severe mutations diminish mRNA stability, and serve as functional null alleles that block chain assembly by resulting in either a deficiency (in the nonlethal mitis variety) or a complete absence (in lethal Herlitz-JEB) of one of the chains needed for laminin-5 heterotrimer assembly.

Antigenic expression of integrin alpha 6 beta 4 in junctional epidermolysis bullosa.

Integrin alpha 6 beta 4 is a major component of hemidesmosomes, considered to play a central role in the adhesion of basal epidermal cells to the underlying dermis. It is therefore of considerable interest in the study of the aetiology of inherited blistering disorders. We have examined the immunohistochemical characteristics of skin from 16 patients with epidermolysis bullosa using two antibodies directed against epitopes on the beta 4 subunit of alpha beta 4 integrin (G71, 3E1), one antibody directed against an epitope on the alpha 6 subunit (GoH3), GB3 an antibody for nicein, and LH7.2, an anticollagen type VII antibody. All 10 patients with junctional epidermolysis bullosa showed markedly reduced or no immunoreactivity with G71. These patients included two with GB3-positive junctional epidermolysis bullosa associated with pyloric atresia, and four with other subtypes. By contrast, five patients with dystrophic epidermolysis bullosa and one patient with epidermolysis bullosa simplex showed normal immunoreactivity with G71. In this study, G71 is shown to have a high specificity and sensitivity for the diagnosis of junctional epidermolysis bullosa. Immunoreactivity with 3E1 and GoH3 was normal in most patients, consistent with published reports showing normal immunoreactivity with other beta 4 and alpha 6 subunit antibodies. The data suggest a modification of the beta 4 subunit of integrin alpha 6 beta 4 at the dermo-epidermal junction in junctional epidermolysis bullosa.