Cardiac Troponin T (TNNT2) mutations are less prevalent in Indian hypertrophic cardiomyopathy patients

Abstract

We sought to determine the frequency of the genetic variations in the Troponin T (TNNT2) gene and its association in Indian cardiomyopathy patients. Sequencing of the entire TNNT2 gene in 162 Hypertrophic Cardiomyopathy (HCM) patients, along with 179 healthy controls, revealed a total of 15 variants. These included an A28V missense mutation, a novel Single-Nucleotide Polymorphism (SNP) (g.7239;G→A) predicted to disturb the splicing significantly, three SNPs, rs3729547 (C→T), rs3729843 (G→A), rs3729842 (C→T), which were in high linkage disequilibrium, and a 5bp polymorphism that skipped exon 4 during splicing, which was found to be significantly higher in HCM patients (del/del genotype, p = 0.00011; deletion allele, p = 0.00008). Further studies on the 5 bp polymorphism in 2092 randomly selected individuals belonging to 39 ethnic and endogamous populations from 19 states of India and representing the major linguistic Indian families, revealed that the South and the Northwest Indians have a high frequency of 5 bp deletions. The missense mutations in TNNT2 are responsible for 15%–20% of familial HCM by impairing the function of the heart muscle. However, other than the 5 bp polymorphism, our comprehensive study on the Indian HCM patients have lowered the occurrence and overall prevalence of supposedly more aggressive and worst disease causing percentage of missense mutations in TNNT2 dramatically.