Heterozygous COL17A1 variants are a frequent cause of amelogenesis imperfecta.

BACKGROUND: Collagen XVII is most typically associated with human disease when biallelic COL17A1 variants (>230) cause junctional epidermolysis bullosa (JEB), a rare, genetically heterogeneous, mucocutaneous blistering disease with amelogenesis imperfecta (AI), a developmental enamel defect. Despite recognition that heterozygous carriers in JEB families can have AI, and that heterozygous COL17A1 variants also cause dominant corneal epithelial recurrent erosion dystrophy (ERED), the importance of heterozygous COL17A1 variants causing dominant non-syndromic AI is not widely recognised. METHODS: Probands from an AI cohort were screened by single molecule molecular inversion probes or targeted hybridisation capture (both a custom panel and whole exome sequencing) for COL17A1 variants. Patient phenotypes were assessed by clinical examination and analyses of affected teeth. RESULTS: Nineteen unrelated probands with isolated AI (no co-segregating features) had 17 heterozygous, potentially pathogenic COL17A1 variants, including missense, premature termination codons, frameshift and splice site variants in both the endo-domains and the ecto-domains of the protein. The AI phenotype was consistent with enamel of near normal thickness and variable focal hypoplasia with surface irregularities including pitting. CONCLUSION: These results indicate that COL17A1 variants are a frequent cause of dominantly inherited non-syndromic AI. Comparison of variants implicated in AI and JEB identifies similarities in type and distribution, with five identified in both conditions, one of which may also cause ERED. Increased availability of genetic testing means that more individuals will receive reports of heterozygous COL17A1 variants. We propose that patients with isolated AI or ERED, due to COL17A1 variants, should be considered as potential carriers for JEB and counselled accordingly, reflecting the importance of multidisciplinary care.

Junctional Epidermolysis Bullosa in Sprague Dawley Rats Caused by a Frameshift Mutation of Col17a1 Gene.

Junctional epidermolysis bullosa is an intractable cutaneous disorder in humans causing skin fragility and blistering due to mutations in genes encoding essential molecules adhering epidermis and dermis including collagen XVII. However, the pathogenesis still remains to be not fully understood perhaps because of a lack of appropriate animal models. In this study, we report novel mutant rats experiencing junctional epidermolysis bullosa, which was confirmed to be caused by a frameshift mutation of Col17a1 gene, as a rat model for investigating the underlying mechanism of pathogenesis. The mutant rats completely lacked the expression of collagen XVII and had blisters leading to infantile deaths as a homozygous condition, although their skin was apparently normal at birth by light microscopic evaluation except that immunohistochemical examination could not detect collagen XVII in any organs. These observations suggest that collagen XVII is not essential for the development of skin during the prenatal period but is indispensable for keeping epidermal-dermal connections stable after birth. Subsequent electron microscopic examinations further revealed an absence of hemidesmosomal inner plaques being composed of BP230, a binding partner of collagen XVII, and plectin in Col17a1-null newborns, albeit mRNA expressions of these molecules seemed to be unaffected at least during the fetal period. These results suggest that the lack of collagen XVII induces attenuation of hemidesmosomal inner plaques, which in turn destabilizes the epidermis-dermis connection and results in deterioration of epidermal physiology with formation of blisters after birth.

Patients suffering from dystrophic epidermolysis bullosa are prone to developing autoantibodies against skin proteins: A longitudinal confirmational study.

Epidermolysis bullosa (EB) is a heritable skin blistering disease caused by variants in genes coding for proteins that secure cell-cell adhesion and attachment of the epidermis to the dermis. Interestingly, several proteins involved in inherited EB are also associated with autoimmune blistering diseases (AIBD). In this study, we present a long-term follow-up of 15 patients suffering from recessive dystrophic or junctional EB. From these patients, 62 sera were analysed for the presence of autoantibodies associated with AIBD. We show that patients suffering from recessive dystrophic EB (RDEB) are more susceptible to developing autoantibodies against skin proteins than patients suffering from junctional EB (70% vs. 20%, respectively). Interestingly, no correlation with age was observed. Most patients showed reactivity to Type XVII collagen/linear IgA bullous dermatosis autoantigen (n = 5; 33%), followed by BP230 (n = 4; 27%), Type VII collagen (n = 4; 27%) and laminin-332 (n = 1; 7%). The pathogenicity of these autoantibodies remains a subject for future experiments.

Laryngo-Onycho-Cutaneous Syndrome (LOCS).

Shabbir Syndrome or commonly known as Laryngo-onycho-cutaneous syndrome (LOCS) is an autosomal recessively inherited syndrome, caused due to mutations in the laminin alpha-3 (LAMA3) gene. This syndrome affects the epidermal layer and results in granulation formation in the eyes, larynx, and nails. One of the most dreadful complications of this syndrome can be due to granulation formation in the larynx or sub-glottis region resulting in laryngeal stenosis and death. According to the latest Online Mendelian Inheritance in Man (OMIM) classification, LOCS has been reclassified as a subtype of Junctional epidermolysis bullosa (JEB). But it is still considered a rare syndrome with limited cases reported worldwide. In this case report, we have discussed a case of a four year old, Pakistani boy, who presented with stridor, fragile skin, and granulation of nails, with no family history of LOCS.

Paired nicking-mediated COL17A1 reframing for junctional epidermolysis bullosa.

Junctional epidermolysis bullosa (JEB) is a debilitating hereditary skin disorder caused by mutations in genes encoding laminin-332, type XVII collagen (C17), and integrin-α6ß4, which maintain stability between the dermis and epidermis. We designed patient-specific Cas9-nuclease- and -nickase-based targeting strategies for reframing a common homozygous deletion in exon 52 of COL17A1 associated with a lack of full-length C17 expression. Subsequent characterization of protein restoration, indel composition, and divergence of DNA and mRNA outcomes after treatment revealed auspicious efficiency, safety, and precision profiles for paired nicking-based COL17A1 editing. Almost 46% of treated primary JEB keratinocytes expressed reframed C17. Reframed COL17A1 transcripts predominantly featured 25- and 37-nt deletions, accounting for >42% of all edits and encoding C17 protein variants that localized accurately to the cell membrane. Furthermore, corrected cells showed accurate shedding of the extracellular 120-kDa C17 domain and improved adhesion capabilities to laminin-332 compared with untreated JEB cells. Three-dimensional (3D) skin equivalents demonstrated accurate and continuous deposition of C17 within the basal membrane zone between epidermis and dermis. Our findings constitute, for the first time, gene-editing-based correction of a COL17A1 mutation and demonstrate the superiority of proximal paired nicking strategies based on Cas9 D10A nickase over wild-type Cas9-based strategies for gene reframing in a clinical context.

Phenotypic variability in LAMA3-associated amelogenesis imperfecta.

OBJECTIVE: Amelogenesis imperfecta (AI) is defined as inherited enamel malformations. LAMA3 (laminin alpha-3) encodes a critical protein component of the basement membrane (laminin-332). Individuals carrying heterozygous LAMA3 mutations have previously been shown to have localized enamel defects. This study aimed to define clinical phenotypes and to discern the genetic etiology for four AI kindreds. MATERIALS AND METHODS: Whole-exome analyses were conducted to search for sequence variants associated with the disorder, and micro-computed tomography (µCT) to characterize the enamel defects. RESULTS: The predominant enamel phenotype was generalized thin enamel with defective pits and grooves. Horizonal bands of hypoplastic enamel with chalky-white discoloration and enamel hypomineralization were also observed and demonstrated by µCT analyses of affected teeth. Four disease-causing LAMA3 mutations (NM_198129.4:c.3712dup; c.5891dup; c.7367del; c.9400G > C) were identified. Compound heterozygous MMP20 mutations (NM_004771.4:c.539A > G; c.692C > T) were also found in one proband with more severe enamel defects, suggesting a mutational synergism on disease phenotypes. Further analyses of the AI-causing mutations suggested that both α3A (short) and α3B (long) isoforms of LAMA3 are essential for enamel formation. CONCLUSIONS: Heterozygous LAMA3 mutations can cause generalized enamel defects (AI1A) with variable expressivity. Laminin-332 is critical not only for appositional growth but also enamel maturation.

A Novel Fluorescence-Based Screen of Gene Editing Molecules for Junctional Epidermolysis Bullosa.

Junctional epidermolysis bullosa (JEB) is a severe blistering skin disease caused by mutations in genes encoding structural proteins essential for skin integrity. In this study, we developed a cell line suitable for gene expression studies of the JEB-associated COL17A1 encoding type XVII collagen (C17), a transmembrane protein involved in connecting basal keratinocytes to the underlying dermis of the skin. Using the CRISPR/Cas9 system of Streptococcus pyogenes we fused the coding sequence of GFP to COL17A1 leading to the constitutive expression of GFP-C17 fusion proteins under the control of the endogenous promoter in human wild-type and JEB keratinocytes. We confirmed the accurate full-length expression and localization of GFP-C17 to the plasma membrane via fluorescence microscopy and Western blot analysis. As expected, the expression of GFP-C17mut fusion proteins in JEB keratinocytes generated no specific GFP signal. However, the CRISPR/Cas9-mediated repair of a JEB-associated frameshift mutation in GFP-COL17A1mut-expressing JEB cells led to the restoration of GFP-C17, apparent in the full-length expression of the fusion protein, its accurate localization within the plasma membrane of keratinocyte monolayers as well as within the basement membrane zone of 3D-skin equivalents. Thus, this fluorescence-based JEB cell line provides the potential to serve as a platform to screen for personalized gene editing molecules and applications in vitro and in appropriate animal models in vivo.

Successful kidney transplantation in a patient with neonatal-onset ILNEB.

BACKGROUND: ILNEB constitute an autosomal recessive disorder caused by homozygous or compound heterozygous mutation of the gene for the ITGA3. To date, 8 ILNEB patients have been reported, but all 6 neonatal-onset ILNEB patients suffered early death within 2 years. The most common cause of death among previously reported ILNEB patients was exacerbation of the respiratory condition. METHODS: In this study, we describe a case of ILNEB with neonatal onset in a female patient and the genetic and histopathological testing performed. RESULTS: Our patient had a compound heterozygous mutation in ITGA3. Compared to previously reported patients, this patient exhibited milder clinical and histopathological characteristics. After experiencing a life-threatening respiratory infection at 8 months old, the patient started periodic subcutaneous immunoglobulin treatment once every 1-2 weeks for nephrotic-range proteinuria-induced secondary hypogammaglobulinemia. At the age of 3 years, proteinuria gradually increased with severe edema despite strict internal management. Therefore, our patient underwent unilateral nephrectomy and insertion of a peritoneal dialysis catheter followed by another unilateral nephrectomy. One month later, she underwent an ABO-compatible living-donor kidney transplantation at the age of 4 years. CONCLUSIONS: Our patient is a neonatal-onset ILNEB patient who survived for more than 2 years and underwent successful kidney transplantation.

Personalized Development of Antisense Oligonucleotides for Exon Skipping Restores Type XVII Collagen Expression in Junctional Epidermolysis Bullosa.

Intermediate junctional epidermolysis bullosa caused by mutations in the COL17A1 gene is characterized by the frequent development of blisters and erosions on the skin and mucous membranes. The rarity of the disease and the heterogeneity of the underlying mutations renders therapy developments challenging. However, the high number of short in-frame exons facilitates the use of antisense oligonucleotides (AON) to restore collagen 17 (C17) expression by inducing exon skipping. In a personalized approach, we designed and tested three AONs in combination with a cationic liposomal carrier for their ability to induce skipping of COL17A1 exon 7 in 2D culture and in 3D skin equivalents. We show that AON-induced exon skipping excludes the targeted exon from pre-mRNA processing, which restores the reading frame, leading to the expression of a slightly truncated protein. Furthermore, the expression and correct deposition of C17 at the dermal-epidermal junction indicates its functionality. Thus, we assume AON-mediated exon skipping to be a promising tool for the treatment of junctional epidermolysis bullosa, particularly applicable in a personalized manner for rare genotypes.

Efficacy of gentamicin 0.3% solution of oral erosions healing in patients with severe generalized recessive dystrophic epidermolysis bullosa and its impact on the expression of type VII collagen.

INTRODUCTION: Epidermolysis bullosa (EB) is a rare genetic skin disorder inherited either in autosomal recessive (AR) or autosomal dominant (AD) manner and characterized by blistering of the skin and mucous membranes. According to a subtype of EB, the oral manifestations and dental involvement vary in frequency and in severity. The most severe dental problems occur in patients with junctional epidermolysis bullosa (JEB) and severe generalized dystrophic epidermolysis bullosa (RDEB) and involve enamel erosion and development of blisters followed by painful oral wounds. Oral mucosa lesions decrease patients' quality of life and may contribute to difficulties in nutrition leading to cachexia. AIM: Assessment of efficacy of gentamicin 0.3% solution in the healing and preventing of oral erosions in patients with RDEB and evaluating its impact on the expression of type VII collagen. MATERIAL AND METHODS: The study included four female patients with RDEB, aged 16-42 who show different mutations in the COL7A1 gene and were administered the mouth rinse two times daily with a solution of 0.3% gentamycin for 4 consecutive weeks. Prior to and at the end of the study, the samples from oral mucosa were collected to estimate the expression of type VII collagen by immunofluorescence test. RESULTS: The clinical improvement of oral wounds healing and reduced number of new blisters and mucous membrane soreness as well as partial re-expression of type VII collagen was observed in all studied patients. CONCLUSIONS: Topical gentamicin therapy of oral cavity in RDEB patients resulted in clinical improvement of mucosal lesions and re-expression of collagen type VII.

Attenuation of Severe Generalized Junctional Epidermolysis Bullosa by Systemic Treatment with Gentamicin.

Severe generalized junctional epidermolysis bullosa (JEB), a lethal genodermatosis, is mainly caused by premature termination codons (PTCs) in one of the three genes encoding the anchoring protein laminin-332. Only symptomatic treatment has been established; overcoming PTCs by aminoglycosides may represent an interesting alternative. This retrospective study aimed at assessing for the first time the clinical effects of systemic gentamicin application in infants with severe generalized JEB. Five patients, homozygous or compound-heterozygous for PTCs in the gene LAMB3, were treated with gentamicin which was administered intravenously or by intramuscular injection at doses of 7.5 mg/kg/d for three weeks. Skin biopsies were investigated by immunofluorescence analyses. Clinical effects of the medication were recorded with a parent questionnaire and by assessing weight-for-age charts. Gentamicin application was well tolerated, long hospitalization was not required. Low levels of laminin-332 could be detected in a skin sample obtained after treatment. Gentamicin had a positive impact on skin fragility and daily life in four patients but did not influence weight gain and failed to reverse the lethal course of the disease. Gentamicin injections should be considered regularly in cases of severe generalized JEB caused by PTCs as they may attenuate JEB symptoms without impeding quality of life.

A Nonlethal Case of Junctional Epidermolysis Bullosa and Congenital Pyloric Atresia: Compound Heterozygosity in a Patient with a Novel Integrin Beta 4 Gene Mutation.

We report a case of nonfatal junctional epidermolysis bullosa and pyloric atresia in a newborn. We identified a substitution (c.914C>T) for the integrin ß4 gene that has been associated with favorable outcome. A novel mutation (c.2011T>G) of unknown significance was also found in this patient who is now thriving.

Treatment of chronic infected post-oncological wounds with a dermal matrix: two case studies.

The reconstruction of complex wounds in patients with comorbidities in the lower extremities is a challenging problem for surgeons. Skin grafting is frequently used to cover large skin defects, but it has several limits, including unwanted outcomes resulting from scars, poor elasticity and limitations in joint movement due to contractures. Locoregional flaps, particularly in the lower limbs, have limited application due to the size of the defect. Tissue engineering of the skin has offered major improvements in the coverage of large defects. Dermal matrix can be applied in order to generate a new dermis that allows good re-epithelialisation or skin grafting at a later stage. The reconstruction of large lower limb defects is more complicated in the case of chronic wounds showing no tendency to heal due to chronic infection. For all surgeons, it is very important to prevent the formation of a biofilm or manage it when it is already established before undertaking surgical procedures that involve a dermal matrix. We report our reconstruction strategy of chronic infected neoplastic ulcers of the lower extremities with a dermal matrix and our postoperative dressing protocol.

Epidermolysis Bullosa with Pyloric Atresia and Aplasia Cutis in a Newborn Due to Homozygous Mutation in ITGB4.

BACKGROUND: Epidermolysis bullosa with pyloric atresia (EB-PA) is an autosomal recessive disorder due to mutations in ITGA6 and/or ITGB4, resulting in altered expression of α6ß4 integrin. EB-PA can also occur with aplasia cutis. CASE REPORT: We present a newborn with EB-PA and aplasia cutis, born of consanguineous parents, with a homozygous c.3793+1G>A mutation affecting ITGB4, previously described only in the heterozygous state with other mutations. CONCLUSION: The previously unreported homozygous c.3793+1G>A mutation affecting ITGB4 causes a severe form of junctional epidermolysis bullosa with pyloric atresia and aplasia cutis.

A stop-gain in the laminin, alpha 3 gene causes recessive junctional epidermolysis bullosa in Belgian Blue cattle.

Four newborn purebred Belgian Blue calves presenting a severe form of epidermolysis bullosa were recently referred to our heredo-surveillance platform. SNP array genotyping followed by autozygosity mapping located the causative gene in a 8.3-Mb interval on bovine chromosome 24. Combining information from (i) whole-genome sequencing of an affected calf, (ii) transcriptomic data from a panel of tissues and (iii) a list of functionally ranked positional candidates pinpointed a private G to A nucleotide substitution in the LAMA3 gene that creates a premature stop codon (p.Arg2609*) in exon 60, truncating 22% of the corresponding protein. The LAMA3 gene encodes the alpha 3 subunit of the heterotrimeric laminin-332, a key constituent of the lamina lucida that is part of the skin basement membrane connecting epidermis and dermis layers. Homozygous loss-of-function mutations in this gene are known to cause severe junctional epidermolysis bullosa in human, mice, horse, sheep and dog. Overall, our data strongly support the causality of the identified gene and mutation.

Successful therapeutic transplantation of revertant skin in epidermolysis bullosa.

BACKGROUND: Epidermolysis bullosa (EB) is a group of genetic blistering diseases. Despite many efforts, treatment for EB remains symptomatic. Revertant mosaicism, coexistence of cells carrying disease-causing mutations with cells in which the inherited mutation is genetically corrected by a spontaneous genetic event (revertant cells) in 1 individual, can be found in EB. The naturally corrected revertant keratinocytes provide an opportunity for autologous cell therapy. OBJECTIVE: We sought to locally treat EB by transplantation of revertant skin. METHODS: Persistent ulcers in a patient with non-Herlitz junctional EB caused by mutations in the LAMB3 gene were treated by transplantation of split-thickness biopsy specimens from one of his revertant patches. RESULTS: All transplanted biopsy specimens were accepted and complete re-epithelialization occurred within 14 days. During 18 months of follow-up, the patient never experienced blisters or wounds in the grafted area, nor in the healed donor site. Immunofluorescence and DNA sequencing showed that acceptor sites healed with transplanted revertant keratinocytes. LIMITATIONS: Punch grafting allows only limited expansion of revertant skin. CONCLUSIONS: We demonstrate that phenotypical and genotypical correction of skin in patients with revertant mosaicism by expansion of revertant skin might be a promising therapeutic option for cutaneous manifestations of EB.

Junctional Epidermolysis Bullosa Associated Laryngeal Stenosis: A Case Report and Review of Literature.

Introduction: Introduction: Junctional Epidermolysis Bullosa (JEB) is a rare subtype of the Epidermolysis Bullosa which itself is a rare genetic disorder. While mucosal involvement of pharynx and oesophagus has been reported, laryngeal involvement is rare. Case Report: A 7-month-old male child who was known to have Junctional Epidermolysis Bullosa presented to the emergency department with respiratory distress associated with a stridor which was eventfully found to have multiple level laryngeal stenosis. Conclusions: Longitudinal cohort studies are required to determine the long-term outcome and the anticipated behavior of epidermolysis bullosa in patients with laryngeal manifestation to avoid unnecessary surgical interventions.