Hemidesmosomal variants of epidermolysis bullosa

Abstract: Epidermolysis bullosa (EB), a heterogeneous group of genodermatoses, is characterized by fragility and blistering of the skin, associated with characteristic extracutaneous manifestations. Based on clinical severity, constellation of the phenotypic manifestations, and the level of tissue separation within the cutaneous basement membrane zone, EB has been divided into distinct subcategories. Traditionally, these include the simplex, junctional and dystrophic variants of EB. Recent attention has been drawn to variants of EB demonstrating tissue separation at the level of hemidesmosomes, ultrastructurally recognizable adhesion complexes within the cutaneous basement membrane zone. Clinically, these hemidesmosomal variants manifest either as generalized atrophic benign epidermolysis bullosa (GABEB), EB with pyloric atresia, or EB with late-onset muscular dystrophy, Elucidation of basement membrane zone components by molecular cloning and development of mutation detection strategies have revealed that the hemidesmosomal variants of EB result from mutations in the genes encoding the subunit polypeptides of the 180-kD bullous pemphigoid antigen/type XVII collagen, the α₆β₄ integrin, or plectin, respectively. Collectively, these data add to the understanding of the molecular complexity of the cutaneous basement membrane zone in EB, as attested by the fact that mutations in 10 different genes can underlie different variants of EB. Elucidation of mutations in different forms of EB has direct application to genetic counseling and DNA-based prenatal testing in families with EB.     

Clinical evaluation of patients with epidermolysis bullosa: Review of the literature and case reports

Epidermolysis bullosa (EB) is a relatively rare inherited disorder, which includes blister and vesicle formation on the skin and mucous membranes as a result of trauma or heat. There are different forms of this disorder. Mild manifestations are relatively uncomfortable, usually involving the knees, elbows, and fingers. Severe forms of this disease compromise normal functioning of multiple organs, which may result in premature death. The lack of a specific treatment to cure EB makes genetic counseling and prenatal diagnosis of primary importance to control this disorder. Three case histories of persons with dystrophic recessive epidermolysis bullosa are reported, focusing on appropriate dental care for patients with EB.     

Identification of the LAMB3 hotspot mutation R635X in a Hungarian case of Herlitz junctional epidermolysis bullosa

Abstract The Herlitz type of junctional epidermolysis bullosa (H-JEB) is a serve blistering disease affecting the skin and mucous membranes, which is usually lethal within the first year of life. The laminin 5 genes have been implicated as candidate genes for most patients with H-JEB. Recently two hotspot mutations were delineated in the LAMB3 gene, known as R42X and R635X, and have been noted in over 50% of mutant LAMB3 alleles. Here, we present a case of H-JEB of Hungarian origin with a neonatal lethal outcome. Monoclonal antibody staining showed a lack of expression of the laminin 5β3 chain, as a possible result of a mutation in one of the laminin 5 genes. Screening of the family identified the previously described mutation R635X in exon 14 of LAMB3 in each of the parents and one healthy sibling in the heterozygous form, while proband was homozygous for R635X, and the other sibling proved to be genotypically normal. These results underscore the widespread prevalence of R635X in H-JEB cases form around the world.     

中毒性表皮松解症的护理

目的 总结中毒性表皮松解症（TEN）患者的护理经验，提高护理质量，有效地促进患者康复。方法 对我院皮肤科2000～2004年收治的15例TEN患者，从皮肤、眼部并发症以及各重要系统并发症的护理及营养支持，感染控制，心理支持等方面进行总结。结果 15例患者中13例痊愈出院，2例分别继发肺部感染和感染综合征死亡。结论 细致到位的护理在TEN患者的治疗过程中起到了重要作用，能有效的促进患者康复。     

Transplantation of autologous single hair units heals chronic wounds in autosomal recessive dystrophic epidermolysis bullosa: A proof-of-concept study

Autosomal recessive dystrophic epidermolysis bullosa (RDEB) is characterized by recurrent mucocutaneous blistering with non-healing ulcers which are often complicated by squamous cell carcinoma (SCC). Despite having as high as 80% death rate from SCC, RDEB still does not have an effective treatment. We report on the efficacy of single follicular unit extract (FUE) grafting to heal chronic ulcers of intermediate RDEB in a 54-year-old woman with extensive chronic wounds covering around 30% of the body surface area. On Day 17 post first graft session, the area of treated ulcers on her right upper back was reduced by 80%. Immunofluorescence study revealed positive type VII collagen expression along the epidermal and follicular basement membrane zone in the donor and recipient sites. A few grafted follicles continued to grow hair on the recipient sites. A total of 360 FUEs were grafted in nine sessions over five years, resulting in healing of most treated ulcers and reduced significantly her time for daily wound dressing. Importantly, FUE grafting using patient's own scalp follicles does not require any laboratory manipulation. It is safe and easy to perform. Autologous follicular grafting appears efficacious for healing of recalcitrant wounds and provides an innovative solution for RDEB patients with such wounds.     

Inherited blistering skin diseases: underlying molecular mechanisms and emerging therapies

Abstract

A key function of human skin is the formation of a structural barrier against the external environment. In part, this is achieved through the formation of a cornified cell envelope derived from a stratified squamous epithelium attached to an epithelial basement membrane. Resilient in health, the structural integrity of skin can become impaired or break down in a collection of inherited skin diseases, referred to as the blistering genodermatoses. These disorders arise from inherited gene mutations in a variety of structural and signalling proteins and manifest clinically as blisters or erosions following minor skin trauma. In some patients, blistering can be severe resulting in significant morbidity. Furthermore, a number of these conditions are associated with debilitating extra-cutaneous manifestations including gastro-intestinal, cardiac, and ocular complications. In recent years, an improved understanding of the molecular basis of the blistering genodermatoses has led to better disease classification and genetic counselling. For patients, this has also advanced translational research with the advent of new clinical trials of gene, protein, cell, drug, and small molecule therapies. Although curing inherited blistering skin diseases still remains elusive, significant improvements in patients’ quality of life are already being achieved.     

Plectin and human genetic disorders of the skin and muscle

Abstract Recent progress in understanding the molecular organization of the cutaneous basement membrane zone (BMZ) has revealed an intricate network of structural proteins necessary for stable association of the epidermis to the underlying dermis. Molecular genetics of the cutaneous BMZ has also revealed that defects in as many as nine distinct genes within the dermal-epidermal junction which result in different forms of epidermolysis bullosa (EB). a group of heritable mechano-bullous disorders. We have recently demonstrated that a variant of EB associated with late-onset development of muscular dystrophy (EB-MD. MIM no. 226670) results from mutations in the gene encoding plectin (PLEC1). a cytoskeleton associated attachment protein present in the hemidesmosomal inner plaque and the sarcolemma of the muscle. Consequently, mutations in this multi-functional gene/protein system can result in phenotypic manifestations of EB-MD both in the skin and the muscle. In this overview, we will summarize the domain organization of plectin and the structure of the corresponding gene (PLEC1). as well as the genetic basis of EB-MD in families studied thus far. Elucidation of the molecular basis of this subtype of EB adds to our understanding of the structural and functional complexity of the cutaneous BMZ.     

Clinical Criteria for Differentiating between Recessive and Dominant Forms of Dystrophic Epidermolysis Bullosa,Elaborated from an Analysis of 119 Cases

We attempted to establish clinical criteria which differentiated between recessive dystrophic epidermolysis bullosa (RDEB) and dominant DEB (DDEB), since these two groups show prominent differences in prognosis, genetic recurrence risk and response to some types of treatment. The total of 119 cases examined consisted of our own 9 cases (2 of RDEB and 7 of DDEB) and 110 cases (26 of RDEB and 84 of DDEB) collected from the medical literature. They were analyzed by calculating the sensitivity and specificity of ten clinical features. We concluded that, syndactyly, presence of complications, dental lesions, remission-less course, and oral lesions are strongly indicative of RDEB (more than 70% specific). Intractable skin ulcer is suggestive of RDEB (more than 55% specific). Nail lesions, scar and atrophy, milia and pigmentation are not helpful in the differentiation because of their commonality. The proposed criteria are simple, reliable, and practical, providing us with a useful tool for differentiation of RDEB and DDEB in daily practice.     

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.