Identification of novel pathogenic variants of Calpain-3 gene in limb girdle muscular dystrophy R1.

BACKGROUND: Limb Girdle Muscular Dystrophy R1 (LGMDR1) is an autosomal recessive neuromuscular disease caused by mutations in the calpain-3 (CAPN3) gene. As clinical and pathological features may overlap with other types of LGMD, therefore definite molecular diagnosis is required to understand the progression of this debilitating disease. This study aims to identify novel variants of CAPN3 gene in LGMDR1 patients. RESULTS: Thirty-four patients with clinical and histopathological features suggestive of LGMD were studied. The muscle biopsy samples were evaluated using Enzyme histochemistry, Immunohistochemistry, followed by Western Blotting and Sanger sequencing. Out of 34 LGMD cases, 13 patients were diagnosed as LGMDR1 by immunoblot analysis, demonstrating reduced or absent calpain-3 protein as compared to controls. Variants of CAPN3 gene were also found and pathogenicity was predicted using in-silico prediction tools. The CAPN3 gene variants found in this study, included, two missense variants [CAPN3: c.1189T > C, CAPN3: c.2338G > C], one insertion-deletion [c.1688delinsTC], one splice site variant [c.2051-1G > T], and one nonsense variant [c.1939G > T; p.Glu647Ter]. CONCLUSIONS: We confirmed 6 patients as LGMDR1 (with CAPN3 variants) from our cohort and calpain-3 protein expression was significantly reduced by immunoblot analysis as compared to control. Besides the previously known variants, our study found two novel variants in CAPN3 gene by Sanger sequencing-based approach indicating that genetic variants in LGMDR1 patients may help to understand the etiology of the disease and future prognostication.

Differences among Indian and European pemphigus patients based on demographics, clinical parameters and propensity for relapse: results of a prospective bicontinental cohort study.

Limited studies have explored pemphigus variations among different ethnic groups residing in their respective geographical locations. This bicontinental study aimed to compare clinical and immunological parameters in Indian and European pemphigus patients in complete remission, off therapy, or on minimal therapy. 105 patients (India, n= 75; Bulgaria, n=15; Greece, n=15) with pemphigus vulgaris (PV) or pemphigus foliaceous (PF) in complete remission on minimal therapy (n=64) or complete remission off therapy (n=41) were recruited. Demographic, clinical, and immunological parameters were compared. Indian patients were significantly younger, the maximal disease severity during the preceding active disease phase was significantly lower, and treatment duration until complete remission was significantly shorter, compared to European patients. European patients had significantly higher anti-Dsg3 serum levels and higher IgG positivity rate based on direct immunofluorescence microscopy at baseline. Furthermore, European patients revealed higher CD19, CD19+ CD27+ cell counts, compared with patients from India. Of note, none of the European patients (n=30) relapsed within the study period, in contrast to 29/75 (38.6%) Indian patients. Treatment strategies differed significantly between the two cohorts, with more frequent utilization of rituximab to achieve remission in the Indian cohort, while prednisolone was more widely used for maintaining remission in the European cohort. The observed heterogeneity of pemphigus among patients of different ethnicities in terms of demographics, clinical parameters, and propensity for relapse may be due to genetic background or different treatment strategies.