Clinical and allelic heterogeneity in dystrophic epidermolysis bullosa- lessons from an Indian cohort.

BACKGROUND: Dystrophic epidermolysis bullosa (DEB) is due to variation in the COL7A1 gene. The clinical phenotype and severity depends on the type of variation and domain of the affected protein. OBJECTIVES: To characterize the spectrum of COL7A1 variations in a cohort of DEB patients from India, to correlate these findings with clinical phenotypes and to establish a genotype-phenotype correlation. METHODS: This was a retrospective, observational study involving patients with DEB diagnosed on the basis of clinical manifestations, Immuno-fluorescence antigen mapping (IFM) and genetic analysis. A genotype-phenotype correlation was attempted and observations were further explained using IFM on skin biopsies and molecular dynamic simulations. Descriptive statistics were performed using SPSS version 20.0 with P values of <0.05 considered significant. RESULTS: We report 68 unrelated Indian DEB patients classified as RDEB-Intermediate (RDEB-I), RDEB-Severe (RDEB-S) or DDEB based on the EB diagnostic matrix, immunofluorescence antigen mapping and genetic data. Of 68 DEB patients, 59 (86.76%) were inherited in a recessive pattern (RDEB) and 9 (13.24%) in a dominant pattern (DDEB). Limbal stem cell deficiency was seen in four cases of RDEB-S very early in the course of the disease. A total of 88 variants were detected of which 66 were novel. There were no hotspots and recurrent variations were seen in a very small group of patients. We found a high frequency of compound heterozygotes (CH) in RDEB patients born out of non-consanguineous marriage. RDEB patients older than two years who had oral mucosal involvement, and/or deformities, were more likely to have esophageal involvement. Genotype phenotype correlation showed a higher frequency of extracutaneous manifestations and deformities in patients with Premature Termination Codons (PTCs) than in patients with other variations. Molecular simulation studies in patients with missense mutations showed severe phenotype when they were localized in interrupted regions of GLY-X-Y repeats. CONCLUSION: This large study of DEB patients in South Asia adds to the continually expanding genetic database of this condition. This study has direct implications on management as this group of patients can be screened early and managed appropriately.

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.