Form Of Junctional Epidermolysis Bullosa Research Articles

Epidermolysis Bullosa-A Kindler Syndrome Case Report and Short Literature Review.

Epidermolysis bullosa (EB) represents a group of rare disorders, genetically determined, characterized by skin fragility, blister formation and erosions due to minimal trauma. Depending on the ultrastructural level of skin cleavage, above or below the basement membrane, epidermolysis bullosa can be classified into four major types: simplex, junctional, dystrophic and Kindler Syndrome. In the junctional form of EB, the cleavage level is at the dermo-epidermal junction and the targeted proteins are laminin, type XVII collagen and integrins. The dystrophic form of EB is characterized by cleavage in the dermal layer, collagen VII being the targeted protein. In Kindler EB, multiple levels of cleavage have been described. The mutated gene is FERMT1. Another classification of this disease refers to phenotypic aspects such as extracutaneous lesions, severity, and distribution. The management of epidermolysis bullosa includes supportive wound treatments as well as nutritional support. We present a case of epidermolysis bullosa presented at birth, in a newborn with no family history of bullous skin conditions. The clinical presentation revealed extensive denuded areas and significant skin fragility as well as mucous and nail involvement. Prenatal diagnosis is very hard to achieve due to increased genetic heterogeneity of the disease. The short-term results were good. The importance of prenatal testing and possibilities of diagnosis are reviewed in this article. EB is a devastating disease. The presented case had a favorable evolution, with good short-term results. Significant morbidity can result from secondary infections of blisters and complications of the extracutaneous manifestations.

Transgenic Epidermal Cultures for Junctional Epidermolysis Bullosa — 5-Year Outcomes

SummaryInherited junctional epidermolysis bullosa is a severe genetic skin disease that leads to epidermal loss caused by structural and mechanical fragility of the integuments. There is no established cure for junctional epidermolysis bullosa. We previously reported that genetically corrected autologous epidermal cultures regenerated almost an entire, fully functional epidermis on a child who had a devastating form of junctional epidermolysis bullosa. We now report long-term clinical outcomes in this patient. (Funded by POR FESR 2014–2020 — Regione Emilia-Romagna and others.)

The natural history of laryngo-onycho-cutaneous syndrome: A case series of six pediatric patients and literature review.

Laryngo-onycho-cutaneous syndrome (LOC) is a rare subtype of junctional epidermolysis bullosa (JEB), featuring aberrant granulation tissue formation in the skin, larynx, and eyes. So far, three mutations including the specific (founder) mutation in exon 39 of LAMA3 (c.151dup) have been identified, but sparse data exists regarding the natural history, the genotype-phenotype correlation, and its differentiation from other JEB types. We reviewed our pediatric EB database to identify English children with clinical and genetically diagnosed LOC within the last 15years. Their demographic, clinical, and laboratory data were examined. We searched three databases for case reports of LOC between January 1986 and November 2020 and extracted clinical and molecular details. We identified 6 LOC patients, all female (mean age 5.4years). Periungual hypergranulation and skin fragility were the earliest presenting signs (0-3months), followed by laryngeal stenosis, symblepharon (mean onset 10.7 and 11.8months, respectively), and dental abnormalities. Five children developed anemia at an average of 19.2months. We identified 22 published studies in English with 31 cases. This study delineates the disease course of LOC and highlights the overlap with some forms of JEB. Classical signs/symptoms including anemia appear early in life. Genetic analysis revealed three new LOC-associated variants and underscores the finding that interpretation of skin immunolabeling and molecular diagnostics can be challenging. We provide recommendations on management of this complex syndrome.

Cells from discarded dressings differentiate chronic from acute wounds in patients with Epidermolysis Bullosa

Impaired wound healing complicates a wide range of diseases and represents a major cost to healthcare systems. Here we describe the use of discarded wound dressings as a novel, cost effective, accessible, and non-invasive method of isolating viable human cells present at the site of skin wounds. By analyzing 133 discarded wound dressings from 51 patients with the inherited skin-blistering disease epidermolysis bullosa (EB), we show that large numbers of cells, often in excess of 100 million per day, continually infiltrate wound dressings. We show, that the method is able to differentiate chronic from acute wounds, identifying significant increases in granulocytes in chronic wounds, and we show that patients with the junctional form of EB have significantly more cells infiltrating their wounds compared with patients with recessive dystrophic EB. Finally, we identify subsets of granulocytes and T lymphocytes present in all wounds paving the way for single cell profiling of innate and adaptive immune cells with relevance to wound pathologies. In summary, our study delineates findings in EB that have potential relevance for all chronic wounds, and presents a method of cellular isolation that has wide reaching clinical application.

Recurrent urinary retention: An unusual presentation of laryngo-onycho-cutaneous syndrome

Laryngo-onycho-cutaneous (LOC) first described by Shabbir in 1986 in Muslim families from Punjab is a rare autosomal recessive disorder characterized by increased skin and mucous membrane fragility associated with exuberant granulation. The 4th International Consensus Meeting on “Diagnosis and Classification of Epidermolysis Bullosa” classifies it as a localized form of Junctional Epidermolysis Bullosa (JEB-LOC Syndrome) with mutations in α3 chain of Laminin 332. While laryngeal, ocular, and cutaneous involvement in these cases has been widely reported, urinary tract involvement is relatively rare. We report a case of JEB-LOC syndrome in a child from South India with extensive urethral involvement.

Analysis of the functional consequences of targeted exon deletion in COL7A1 reveals prospects for dystrophic epidermolysis bullosa therapy.

Genetically evoked deficiency of collagen VII causes dystrophic epidermolysis bullosa (DEB)-a debilitating disease characterized by chronic skin fragility and progressive fibrosis. Removal of exons carrying frame-disrupting mutations can reinstate protein expression in genetic diseases. The therapeutic potential of this approach is critically dependent on gene, protein, and disease intrinsic factors. Naturally occurring exon skipping in COL7A1, translating collagen VII, suggests that skipping of exons containing disease-causing mutations may be feasible for the treatment of DEB. However, despite a primarily in-frame arrangement of exons in the COL7A1 gene, no general conclusion of the aptitude of exon skipping for DEB can be drawn, since regulation of collagen VII functionality is complex involving folding, intra- and intermolecular interactions. To directly address this, we deleted two conceptually important exons located at both ends of COL7A1, exon 13, containing recurrent mutations, and exon 105, predicted to impact folding. The resulting recombinantly expressed proteins showed conserved functionality in biochemical and in vitro assays. Injected into DEB mice, the proteins promoted skin stability. By demonstrating functionality of internally deleted collagen VII variants, our study provides support of targeted exon deletion or skipping as a potential therapy to treat a large number of individuals with DEB.

First successful preimplantation genetic diagnosis of epidermolysis bullosa with pyloric atresia: Case study of a novel c.4505-4508insACTC mutation

Epidermolysis bullosa (EB) is an inherited blistering disorder characterized by the fragility of the skin and mucous membranes [1–4]. The disease can be traumatic and lethal especially for newborns and infants however non-lethal variants were reported [5]. Epidermolysis bullosa is categorized in three major groups: EB simplex(EBS), junctional EB (JEB) and dysthrophic EB (DEB) [3, 4, 6] . EB with pyloric atresia (EBPA) is classified as a form of JEB. EBPA; which is inherited in an autosomal recessive manner is characterized by fragile skin and congenital atresia of the gastrointestinal tract (especially pylorus) [7–9]. α6β4 integrin levels are shown to be reduced or absent in EBPA patients. α6β4 of hemidesmosomes attaches the keratinocyte to the basal membrane and is encoded by ITG A6 and ITGB4 genes [8, 10–13] Sequencing analysis shows that ITGB4 accounts for%80, ITGA6 accounts for%5 of EBPA patients [14]. Another binding protein of hemidesmosomes, Plectin also interacts with α6β4. Plectin is encoded by PLEC1 gene and as sequencing analysis shows; accounts for the%15 of EBPA patients [15, 16]. Recently, more than a hundred disease causing mutations for EBPA have been described. [1, 10, 11, 17–23]. In this case study we report an in vitro fertilization (IVF)- preimplantation genetic diagnosis (PGD) cycle with a novel mutation of ITGB4 (c.4505-4508insACTC) to a family with a history of 3 deceased children diagnosed as EBPA. A singleton pregnancy was confirmed at 7-week gestation by ultrasonography. After an uneventful pregnancy period, a healthy baby was born.

Early intra-amniotic gene transfer using lentiviral vector improves skin blistering phenotype in a murine model of Herlitz junctional epidermolysis bullosa

Mutations of the LAMB3 gene cause a lethal form of junctional epidermolysis bullosa (JEB). We hypothesized that early intra-amniotic gene transfer in a severe murine model of JEB would improve or correct the skin phenotype. Time-dated fetuses from heterozygous LAMB3(IAP) breeding pairs underwent ultrasound guided intra-amniotic injection of lentiviral vector encoding the murine LAMB3 gene at embryonic day 8 (E8). Gene expression was monitored by immunohistochemistry. The transgenic laminin-β3 chain was shown to assemble with its endogenous partner chains, resulting in detectable amounts of laminin-332 in the basement membrane zone of skin and mucosa. Ultrastructually, the restoration of ∼60% of hemidesmosomal structures was also noted. Although we could correct the skin phenotype in 11.9% of homozygous LAMB3(IAP) mice, none survived beyond 48 h. However, skin transplants from treated E18 homozygous LAMB3(IAP) fetuses maintained normal appearance for 6 months with persistence of normal assembly of laminin-332. These results demonstrate for the first time long-term phenotypic correction of the skin pathology in a severe model of JEB by in vivo prenatal gene transfer. Although survival remained limited due to the limitations of this mouse model, this study supports the potential for treatment of JEB by prenatal gene transfer.

Zebrafish: A Model System to Study Heritable Skin Diseases

Heritable skin diseases represent a broad spectrum of clinical manifestations due to mutations in ∼500 different genes. A number of model systems have been developed to advance our understanding of the pathomechanisms of genodermatoses. Zebrafish (Danio rerio), a freshwater vertebrate, has a well-characterized genome, the expression of which can be easily manipulated. The larvae develop rapidly, with all major organs having developed by 5-6 days post-fertilization, including the skin, consisting of the epidermis comprising two cell layers and separated from the dermal collagenous matrix by a basement membrane. This perspective highlights the morphological and ultrastructural features of zebrafish skin, in the context of cutaneous gene expression. These observations suggest that zebrafish provide a useful model system to study the molecular aspects of skin development, as well as the pathogenesis and treatment of select heritable skin diseases.

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

ABSTRACTEpidermolysis 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. Immunofluorescence 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.

Autosomal dominant junctional epidermolysis bullosa

Epidermolysis bullosa (EB) encompasses a heterogeneous group of inherited skin disorders associated with trauma-induced blistering. The junctional forms of EB (JEB), Herlitz JEB, non-Herlitz JEB and JEB associated with pyloric atresia have all been attributed to autosomal recessive inheritance. We describe a 7-year-old girl with defective dental enamel, trauma-induced blistering and subsequent scarring. Her mother, a carrier of the mutation p.G627V in the collagen XVII gene (COL17A1) had evidence of hypoplastic dental enamel without skin blistering. Her grandmother had non-Herlitz JEB as a result of a compound heterozygous mutation in COL17A1 (p.G627V and c.3514ins25). To explore the molecular, ultrastructural and immunofluorescence findings of the first case of dominant JEB. Mutational analysis of COL17A1 was performed on the proband's genomic DNA. In addition, transmission electron microscopy and immunofluorescence microscopy were performed on a nonlesional skin biopsy from the proband and an unrelated healthy control. Direct sequencing revealed a heterozygous glycine substitution mutation, p.G627V, in COL17A1. No discernible morphological abnormalities were found on transmission electron microscopy; however, immunofluorescence microscopy revealed findings of an altered distribution pattern for type XVII collagen epitopes close to the dermal-epidermal junction. This report describes the first case of dominant JEB. Although some heterozygous mutations in COL17A1 are known to cause dental abnormalities none were associated with skin fragility. The dominant-negative interference between the proband's mutated type XVII collagen and the wild-type allele appears to render the skin prone to trauma-induced blister formation. Alternatively, other undisclosed modifying genetic or epigenetic factors might explain why the patient gets blistering whereas her mother, who has the same COL17A1 mutation, has no skin fragility.

Discovery of Basement Membrane Zone Ultrastructural Entities by Electron Microscopy

Early studies using transmission electron microscopy of the human skin, performed in the 1950s and 1960s, revealed some of the key landmarks of the basement membrane zone of the dermal–epidermal junction (DEJ). However, it was not until later, with higher resolution imaging, that the full structural complexity of the DEJ became much clearer and better understood. Briggaman and Wheeler (1975a, b) provided the first comprehensive review of the numerous ultrastructural components of the DEJ, accompanied by a terminology that is still in current use. We were then introduced to the concept of a structural, and as we now know, functional, interrelationship between hemidesmosomes, anchoring filaments and anchoring fibrils, which are now recognized as major constituents of the ‘anchoring complex’ linking basal keratinocytes to the basement membrane and superficial dermis. Although electron microscopy studies of the DEJ have been valuable in defining key steps in processes such as normal development, ageing and carcinogenesis, a major application has been in the studies of blistering disorders, both hereditary and acquired. Pearson (1962) delineated the differences between the primary levels of skin separation in the three main types of hereditary epidermolysis bullosa, and others drew attention to disorders of anchoring fibrils in the dystrophic forms of the disease (Briggaman and Wheeter, 1975a,b; Anton-Lamprecht and Hashimoto, 1976; Tidman and Eady, 1985) when the association between anchoring fibrils and type VII collagen was still unknown. Yet these observations provided an important clue to the later discovery that mutations of type VII collagen, an anchoring fibril component, cause dystrophic epidermolysis bullosa. Other research underscored the importance of structural abnormalities of hemidesmosomes in both the Herlitz (Hashimoto et al., 1976) and non-Herlitz (Tidman and Eady, 1986) forms of junctional epidermolysis bullosa. Localizing antigens in the DEJ at the ultrastructural level has been of lasting interest, especially in studies of autoimmune or congenital bullous disorders. Preliminary research (for example, Schreiner and Wolff, 1970) used horseradish peroxidase to provide an insoluble marker to localize immunoglobulin deposition in lupus erythematosus. However, it was much later, when colloidal gold was introduced to immunoelectron microscopy, that precise molecular localization became possible. Thus, for the first time, we could see convincingly that type VII collagen localized to anchoring fibrils (Sakai et al., 1986) and that kalinin (now known as laminin 5) (Rousselle et al., 1991) was associated with anchoring filaments. The immunolocalization of intracellular proteins, such as bullous pemphigoid antigen 1, was more problematic, initially requiring permeabilization of the cell membrane to allow access of the labelling antibody (Westgate et al., 1985). However, a new approach entailing freeze substitution and post-embedding (or on-section) labelling enabled both intracellular and extracellular antigen labelling with good membrane preservation (Shimizu et al., 1989). Whereas one study (Keene et al., 1987) elegantly demonstrated that anchoring fibrils form an extensive network beneath the lamina densa and link with small discrete ‘anchoring plaques’, another (Shimizu et al., 1997) found that nearly all anchoring fibrils insert at both ends in the lamina densa. These contrasting findings have probably come about because of major differences in skin sample processing and the mode of gold labelling. The former used a pre-embedding en-bloc labelling method, and the latter a post-embedding technique, as described above.

Genetic Manipulation of Skin Stem Cells: Success, Hope, and Challenges Ahead

Gene therapy has been suggested as a potential cure for patients with disabling genetic diseases. The possibility of using gene transfer to treat diseases of the skin was suggested nearly 20 years ago by a report demonstrating that human keratinocyte stem cells1 could be genetically manipulated ex vivo using recombinant retroviruses.2 These early studies led to painstaking efforts by many groups, such as those led by De Luca, to develop gene transfer strategies with clinical potential to treat skin disease.3 The successful transplantation of keratinocyte stem cells genetically corrected ex vivo to treat a rare form of junctional epidermolysis bullosa (JEB) by Mavilio et al.4 unambiguously demonstrates the feasibility of gene therapy in the skin. The new work lends credence to the opinion that gene therapy may soon be part of our therapeutic arsenal and that it may eventually allow us to improve the lives of patients suffering from this horrendous skin disease.

Laminin-5-deficient human keratinocytes: Defective adhesion results in a saltatory and inefficient mode of migration

Laminin-5 is a major adhesion protein of the skin basement membrane and crucially involved in integrin-mediated cell substrate attachment of keratinocytes, which is important for hemidesmosomal anchorage as well as for keratinocyte migration during epidermal wound healing. To investigate its role in keratinocyte migration, we analyzed laminin-5-deficient cells of patients with a lethal variant of junctional epidermolysis bullosa. Normal migrating keratinocytes adopted monopolar morphology with a distinct front lamella and employed a continuous mode of translocation. In contrast, laminin-5-deficient cells assumed a stretched bipolar shape with two lamella regions and migrated in a discontinuous, saltatory manner characterized by significantly decreased directional persistence and reduced migration velocity. The distinct morphology as well as the migratory phenotype apparently resulted from a defect in the formation of cell substrate adhesions that were completely missing in the cell body and less stable in the lamella regions. Accordingly in normal keratinocytes, a bipolar shape and a saltatory migration mode were inducible by blocking laminin-5-mediated substrate adhesion. Our findings clearly point to an essential role of laminin-5 in forming dynamic cell substrate adhesion during migration of epidermal keratinocytes and provide an explanation for the cellular mechanisms that underlie the lethal form of junctional epidermolysis bullosa.

Síndrome de Bart asociado a epidermólisis ampollosa hereditaria letal (Herlitz)

We present the case of a newborn with congenital absence of skin in the anterior part of the left leg that shortly after developed bulla and erosions in hands, feet, ears, buttocks and mouth. The cutaneous biopsy and ultrastructural and immunohistochemical studies showed a subepidermal bulla in the lamina lucida, absence of hemidesmosomes and marked decrease of laminin 5, thus establishing the diagnosis of Bart syndrome associated to the Herlitz form of lethal junctional epidermolysis bullosa. Bart syndrome consists of congenital and localized absence of skin, nail abnormalities and mucoc-cutaneous bullae. It is usually associated to dystrophic epidermolysis bullosa. The Herlitz form of junctional epidermolysis bullosa is a rare variant, usually lethal that is produced by mutations in the genes coding for the anchor protein laminin 5. To our knowledge this is the second case that reports an association between Bart syndrome and lethal junctional epidermolysis bullosa and the first in which the results of immunofluorescence mapping are published.

Targeted Skipping of a Single Exon Harboring a Premature Termination Codon Mutation: Implications and Potential for Gene Correction Therapy for Selective Dystrophic Epidermolysis Bullosa Patients

This study examined the feasibility of antisense oligoribonucleotide (AON) therapy for dystrophic epidermolysis bullosa (DEB). AON was designed to induce skipping of a targeted exon containing a premature termination codon mutation, resulting in restoration of the open reading frame. We targeted exon 70 of COL7A1, as a recurrent mutation 5818delC in Japanese DEB patients was localized to exon 70. We found that one AON induced effective skipping of normal exon 70 containing 16 amino acids. Attachment and migration analyses showed that recombinant collagen without contribution of exon 70 was similar in effect to normal type VII collagen. Next, we synthesized mutation-specific AON by deleting cytosine at 5818. Introduction of this AON into DEB keratinocytes harboring 5818delC showed that the AON induced skipping of exon 70 in the abnormal 5818delC allele. Furthermore, 6.2% of DEB keratinocytes started to express type VII collagen in vitro after application of the mutation-specific AON. Injection of the AON into rat model grafted with DEB keratinocytes and fibroblasts induced a low amount of type VII collagen expression. We conclude that skipping of targeted exons using mutation-specific AON may show potential for future gene therapy for DEB patients.

Prenatal diagnosis of inherited epidermolysis bullosa in a patient with no family history: a case report and literature review

The junctional form of epidermolysis bullosa (EB) is a recessively inherited mechanobullous disease in which minimal trauma results in blister formation at the dermal-epidermal junction. A rare form associated with pyloric atresia (JEB-PA) is a severe clinical subtype leading to rapid demise after birth, thus justifying prenatal diagnosis. The case characterized by abnormal ultrasound findings at 35 weeks of gestation (gastric dilatation associated with polyhydramnios) of a patient with no family history is reported. Postabortion skin biopsies were analyzed by immunofluorescence that revealed marked reduction of integrin alpha6beta4 in accordance with the diagnosis of JEB-PA. Amniotic fluid contained excess total protein (4 MoM), abnormally high AFP (20.4 MoM) related to skin lesions and abnormally elevated digestive enzyme suggestive of fetal vomiting of bile. The electrophoretic pattern of cholinesterases was unusual (additional slow band). Maternal serum AFP was 3.14 MoM and free beta-hCG 13.1 MoM. Because of these concomitant findings, JEB-PA was suspected. The case under study was atypical because of late clinical manifestations of the disease: polyhydramnios, gastric enlargement. As maternal serum AFP at 15 weeks may be normal, it was suggested that discovery of polyhydramnios during the second or the third trimester should prompt biochemical analysis of amniotic fluid, such as AFP and GGTP assay in all cases.

Novel and recurrent mutations in the laminin-5 genes causing lethal junctional epidermolysis bullosa: molecular basis and clinical course of Herlitz disease

Herlitz disease (H-JEB), the lethal form of junctional epidermolysis bullosa, is a rare genodermatosis presenting from birth with widespread erosions and blistering of skin and mucosae because of tissue cleavage within the epidermal basement membrane. Mutations in any of the three genes encoding the alpha3, beta3 and gamma2 chains of laminin-5 underlie this recessively inherited disorder. Here, we report the molecular basis and clinical course of H-JEB in 12 patients. Two novel nonsense mutations in the gene LAMA3 (E281X and K1299X) and a novel frame-shift mutation in the gene LAMB3 (1628insG) leading to a premature termination codon were identified by DNA sequencing and confirmed by restriction fragment length polymorphism analysis. In the four patients affected, neither the resulting truncated polypeptide chains nor assembled laminin-5 protein were detectable by immunofluorescence. Three patients were found to be heterozygous for the known hotspot mutation R635X and the recurrent mutations Q373X or 29insC in the gene LAMB3, whereas five others were homozygous for R635X. Significant variations in the disease progression and survival times between 1 and 30 months in this group of H-JEB patients emphasised the impact of modifying factors and the importance of immunostaining or mRNA assessment as parallel diagnostic methods. Interestingly, the only patients who survived for longer than 6 months were four females carrying the mutation R635X homozygously. In one of them, the clinical course may have been improved by treatment with artificial skin equivalents. These data may stimulate further investigation of genotype-phenotype correlations and facilitate mutation analysis and genetic counselling of affected families.

Rapid Decay of α6 Integrin Caused by a Mis-Sense Mutation in the Propeller Domain Results in Severe Junctional Epidermolysis Bullosa with Pyloric Atresia

Genetic mutations in alpha6beta4 integrin cause junctional epidermolysis bullosa with pyloric atresia, a genodermatosis characterized by blistering of the skin and pyloric occlusion. The lethal form of junctional epidermolysis bullosa with pyloric atresia has been mainly associated with the presence of premature termination codons in the mRNA encoding either the alpha6 or beta4 subunit causing rapid decay of the mutated transcript and absence of alpha6beta4 integrin. In this study, we disclose the genetic background of lethal junctional epidermolysis bullosa with pyloric atresia in a patient presenting absent expression of alpha6 integrin despite normal steady-state level of the alpha6beta4 mRNA. Screening for mutation in the alpha6 gene detected a homozygous base pair substitution (286 C-to-T), which results in the substitution of a serine with a leucine residue (S47L). The amino acid substitution S47L localizes in the first beta-strand of the seven-bladed beta-propeller structure of the extracellular head of alpha6 integrin, and triggers a rapid proteolysis of the aberrant polypeptides involving the lysosomal degradation pathway. This study provides new insight into the pathogenic effect of a mis-sense mutation affecting a functional domain of a protein, and identifies a critical peptide sequence of the beta-propeller domain conserved among the alpha integrin cell receptors.

Targeted Inactivation of Murine Laminin γ2-Chain Gene Recapitulates Human Junctional Epidermolysis Bullosa

Junctional forms of epidermolysis bullosa (JEB) are associated with mutations in six distinct genes expressed in the cutaneous basement membrane zone; these include LAMA3, LAMB3, and LAMC2, which encode laminin 5 subunit polypeptides, the alpha3-, beta3-, and gamma2-chains, respectively. Here we generated a mouse model for JEB by inactivating the laminin gamma2-chain gene by targeted frameshift deletion of exon 8 in Lamc2. Heterozygous mice were phenotypically normal, whereas the majority of Lamc2-/- mice showed blistering phenotype on days 1 to 2 and died within 5 days of birth. The Lamc2-/- mice demonstrated absent expression of laminin gamma2-chain on the basement membrane zone as well as attenuated expression of alpha3- and beta3-chains of laminin. Transmission electron microscopy revealed rudimentary, poorly developed hemidesmosomes. The epidermis of the Lamc2-/- mice revealed induced apoptosis in the basal cells of the blistered skin, suggesting that cell-matrix adhesion provided by laminin 5 plays a role in cell survival in vivo. Cultured Lamc2-/- keratinocytes demonstrated slightly positive staining with gamma2-chain-specific antibodies, which could be explained by the presence of a transcript with partial restoration of the reading frame owing to alternative splicing in vitro. These cells proliferated in different matrices and attached to type IV collagen and Matrigel as efficiently as the wild-type keratinocytes, whereas their attachment on plastic and laminin was significantly weaker. In summary, Lamc2-/- mouse recapitulates human JEB and provides novel insight into the role of laminin 5 in keratinocyte biology.