Abstract

Myotonic dystrophy type 1 is a chronic, slowly progressing, inherited multisystemic autosomal-dominant disease, caused by expansion of CTG repeats in DMPK gene. The purpose of the present study was to analyze molecular expansion profiling of CTG repeat, status of CpG methylation at DMPK gene locus, and to established relationship between CpG methylation and CTG repeat expansion size along with other clinical and biochemical parameters. Clinically suspected 21 DM1 subjects, 56 family members and 50 normal individuals were included in this study. Molecular diagnosis of CTG repeat expansion was performed by Myotonic Dystrophy Short PCR (MDSP) and Triplet primed-PCR (TP-PCR) and followed fragment analysis on ABI-310 Genetic Analyser. The CpG methylation was done by bisulphite conversion kit (Cells to CpGTM Bisulphite conversion kit, 4445555) and 7500 Fast RT-PCR. SPSS version 16 and Pearson correlation coefficient were used for statistical analysis. All clinically suspected 21 subjects had CTG repeat expansion. Among 56 family members, 16 were permutated, and 40 were normal for CTG repeat. Our previous findings (Kumar et al, 2016 and 2018) highlighted that pattern of CTG repeats differs according to ethnicity. Among positive DM1 samples (n=21), 13 samples were methylated. CpG methylation was significantly correlated only with CTG repeat expansion. This methylation may affect the disease environment and expression of neighbor gene which is responsible for disease pathogenesis.

Keywords

myotonic dystrophy type 1 (DM1), CTG repeat expansion, TP-PCR, RT-PCR, CpG methylation, bisulphate, myotonin protein kinase, muscular dystrophy,distal muscles