Dystonin modifiers of junctional epidermolysis bullosa and models of epidermolysis bullosa simplex without dystonia musculorum.

The Lamc2jeb junctional epidermolysis bullosa (EB) mouse model has been used to demonstrate that significant genetic modification of EB symptoms is possible, identifying as modifiers Col17a1 and six other quantitative trait loci, several with strong candidate genes including dystonin (Dst/Bpag1). Here, CRISPR/Cas9 was used to alter exon 23 in mouse skin specific isoform Dst-e (Ensembl GRCm38 transcript name Dst-213, transcript ID ENSMUST00000183302.5, protein size 2639AA) and validate a proposed arginine/glutamine difference at amino acid p1226 in B6 versus 129 mice as a modifier of EB. Frame shift deletions (FSD) in mouse Dst-e exon 23 (Dst-eFSD/FSD) were also identified that cause mice carrying wild-type Lamc2 to develop a phenotype similar to human EB simplex without dystonia musculorum. When combined, Dst-eFSD/FSD modifies Lamc2jeb/jeb (FSD+jeb) induced disease in unexpected ways implicating an altered balance between DST-e (BPAG1e) and a rarely reported rodless DST-eS (BPAG1eS) in epithelium as a possible mechanism. Further, FSD+jeb mice with pinnae removed are found to provide a test bed for studying internal epithelium EB disease and treatment without severe skin disease as a limiting factor while also revealing and accelerating significant nasopharynx symptoms present but not previously noted in Lamc2jeb/jeb mice.

Diacerein 1% Ointment for the Treatment of Epidermolysis Bullosa Simplex: A Randomized, Controlled Trial.

BACKGROUND: In epidermolysis bullosa simplex (EBS), epithelial structural fragility results in blisters and erosions. Diacerein 1% ointment has been shown to reduce this blistering. OBJECTIVE: To evaluate the efficacy and safety of diacerein 1% ointment in the treatment of EBS. METHODS: A double-blind study of 54 patients with EBS were randomized to diacerein 1% or vehicle ointment once daily. The primary endpoint ( ≥60% reduction in body surface area of EBS) and the key secondary endpoint ( ≥2-point reduction in the Investigator’s Global Assessment) were evaluated at 8 weeks. RESULTS: There was no difference in the proportion of patients achieving either key efficacy endpoint between the diacerein 1% and vehicle groups (P>0.05). No difference in treatment emergent adverse events were noted between the groups. In post hoc analysis stratified by EBS subtypes, an IGA score of 0 or 1 was reported in 6 of 13 patients with severe EBS in the diacerein group (46.2%), compared with 2 of 13 patients with severe EBS in the vehicle group (15.4%); (relative risk= 3.08, 95% CI = 0.71, 13.4). CONCLUSIONS: Although there was no significant difference in outcomes between the groups, further study may elucidate the effects of diacerein on EBS lesions, especially in patients with severe EBS. Teng J, Paller AS, Bruckner AL, et al. Diacerein 1% ointment for the treatment of epidermolysis bullosa simplex: a randomized, controlled trial. J Drugs Dermatol. 2023;22(6):599-604. doi:10.36849/JDD.7108.

Novel compound heterozygous mutations in the PLEC gene in a neonate with epidermolysis bullosa simplex with pyloric atresia.

Epidermolysis bullosa (EB) is a heterogeneous group of inherited disorders characterized by the blistering of the skin and mucous membranes. Although the molecular basis of EB has been significantly elucidated, the precise phenotypes of the lethal types of EB have not been completely characterized. Herein, we report a severe case of EB with pyloric atresia (PA). The patient was a Japanese boy who not only had skin lesions but also various complications such as PA, dysphagia, hypotonia, infectious keratitis with corneal ulcer, obstructive uropathy and protein-losing enteropathy. Genetic analysis led to the identification of two novel compound heterozygous mutations in the last exon of the plectin (PLEC) gene. Based on this finding, EB simplex with PA was diagnosed. Immunostaining with anti-plectin antibodies revealed truncated plectin proteins lacking the C-terminus in the patient's skin. We also conducted a prenatal diagnosis in subsequent pregnancy. Our report further highlights the crucial role of plectin in many organs and provides valuable information regarding the phenotypes resulting from mutations in the PLEC gene.

Clinical heterogeneity in epidermolysis bullosa simplex with plectin (PLEC) mutations-A study of six unrelated families from India.

Epidermolysis bullosa simplex (EBS) with plectin mutations is a very rare subtype of EB usually associated with pyloric atresia (PA) or muscular dystrophy (MD). We report six unrelated children between ages 4 and 14 years from India with varied clinical manifestations. Only one had PA, and none has developed MD to date. All except the one with PA presented with early onset blistering along with laryngeal involvement in the form of hoarseness of voice and nail involvement. Patient with PA presented with aplasia cutis and died in the first week. Two patients had predominantly respiratory and gastrointestinal involvement with varying severity while two had features of myasthenic syndrome but no limb-girdle involvement and one patient phenocopied laryngo-onycho-cutaneous (LOC) syndrome. Using whole-exome sequencing, we identified novel mutations in PLEC. Histopathological analysis (Immunofluorescence antigen mapping) showed absence of staining to plectin antibodies. Our observations propose to append a phenotype of EBS, hoarseness of voice and nail dystrophy or LOC-like phenotype with plectin mutations. Long-term follow up is necessary to monitor for the development of muscular dystrophy.

A retrospective analysis of diagnostic testing in a large North American cohort of patients with epidermolysis bullosa.

BACKGROUND: Accurate diagnosis of epidermolysis bullosa (EB) has significant implications for prognosis, management, and genetic counseling. OBJECTIVE: To describe diagnostic testing patterns and assess diagnostic concordance of transmission electron microscopy (TEM), immunofluorescence mapping (IFM), and genetic analysis for EB. METHODS: A retrospective cohort included patients enrolled in the Epidermolysis Bullosa Clinical Characterization and Outcomes Database from January 1, 2004, to July 8, 2019. Tests concluding the same EB type (EB simplex, junctional EB, dominant dystrophic EB, and recessive dystrophic EB) were considered concordant; those concluding different EB types were considered discordant; and those with nonspecific/nondefinitive results were equivocal. RESULTS: A total of 970 diagnostic tests were conducted from 1984 to 2018 in 771 patients. Genetic analyses were performed chronologically later than IFM or TEM (P < .001). The likelihood of undergoing genetic analysis was greater for junctional EB and recessive dystrophic EB, and the same for dominant dystrophic EB as compared with EB simplex. TEM results in 163 patients were equivocal (55%), concordant (42%), and discordant (3%). IFM results in 185 patients were equivocal (54%), concordant (42%), and discordant (4%). LIMITATIONS: Retrospective design. CONCLUSIONS: Diagnostic testing has shifted in favor of genetic analysis. TEM and IFM frequently offer equivocal findings when compared to the specificity afforded by genetic analysis.

Epidermolysis Bullosa in Chinese Patients: Genetic Analysis and Mutation Landscape in 57 Pedigrees and Sporadic Cases.

Epidermolysis bullosa encompasses a group of inherited blistering skin disorders. The pathogenic mutations in 10-25% of patients with epidermolysis bullosa have not been identified by Sanger sequencing. The aims of this study were to identify the pathogenic sequence alterations in a large cohort of Chinese patients with epidermolysis bullosa and to clarify the relationship between clinical phenotypes and genotypes. Whole-exome sequencing was performed on 44 pedigrees and 13 sporadic cases. The results were further confirmed by Sanger sequencing. In total, 52 mutations, comprising 19 novel and 33 previously reported mutations, were identified in 5 genes, with a mutation detection rate of 100%. A relationship between subtypes and pathogenic genes was established: 12 cases of epidermolysis bullosa simplex were associated with mutations in KRT5/14 and PLEC; one case of junctional epidermolysis bullosa carried mutations in ITGB4; and 44 cases of dystrophic epidermolysis bullosa were caused by mutations in COL7A1. The results of this study support whole-exome sequencing as a promising tool in the genetic diagnosis of epidermolysis bullosa.

Locally advanced tongue squamous cell carcinoma in epidermolysis simplex bullosa patient: a therapeutic conundrum.

Epidermolysis bullosa simplex (EBS) is a debilitating condition affecting the skin and mucous membranes that is characterised by frequent ulceration and blistering on trivial trauma. In EBS, oral cavity mucosal injuries lead to a high propensity for developing squamous cell carcinomas. Locally advanced tongue carcinoma arising in this background presents a challenging therapeutic conundrum. To our knowledge, this is the first case of aggressive locally advanced tongue carcinoma that has developed sporadically in a patient with EBS and no family history. Routine screening of oral mucosal lesions will lead to early detection and timely management of this debilitating condition.

Spontaneous KRT5 Gene Mutation in Rhesus Macaques (Macaca mulatta): A Novel Nonhuman Primate Model of Epidermolysis Bullosa Simplex.

Epidermolysis bullosa simplex (EBS) is an inherited skin disorder characterized by increased skin and mucous membrane fragility. Most cases are caused by mutations in keratin 5 (KRT5) and keratin 14 (KRT14). Mutations of these genes result in cytoskeletal disruption of the basal keratinocytes. Gross and histopathologic findings of 2 clinically affected homozygous rhesus macaques with an insertion variant mutation in KRT5 are described and compared with 6 deceased phenotypically normal animals that were heterozygous for the KRT5 insertion variant. Animals that were homozygous for the KRT5 insertion variant were stillborn and had widespread loss of the epidermis. Microscopic examination confirmed severe ulceration and basal cell vacuolation with basilar vesicle formation in the remaining intact epidermis. Immunohistochemistry for cytokeratin 5 demonstrated lack of epidermal immunoreactivity in homozygotes. DNA sequencing identified a 34-base pair insertion variant in exon 5 of the KRT5 gene. To our knowledge, this is the first report of epidermolysis bullosa in rhesus macaques.