Background: Otosclerosis is a common conductive hearing loss resulting from abnormal bone metabolism. The c.788C>T variant in the transforming growth factor-beta 1 gene is associated with otosclerosis in all studied populations, except the Indian population. In this study, we predicted the functional effects of reported variants in transforming growth factor-beta 1 and analyzed the c.788C>T variant in a case–control cohort from India and in the genomes present in public databases.Methods: Clinically confirmed otosclerosis cases (n = 120) and controls (n = 120) were recruited and genotyped by polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing. In addition, Ensembl 1000 Genome, Ensembl NHLBI Exome, GnomAD, and Genome Asia 100K human genome databases were analyzed for allele frequency.Results: Among the 3 variants studied, a significant functional effect was observed only for the c.788C>T variant. This variant was found in 1 case but absent in all others and controls. Odds ratio, 95% CI, and P-value under the dominant model were 1.00, 0.0197-50.8116, and 1.00, respectively. Analysis of genomic databases showed a frequency of 0-11.21% and 0-1.25% for the c.788C>T variant and the individuals homozygous for this variant, respectively.Conclusion: We did not find any genetic association between the c.788C>T variant and otosclerosis in the South Indian population; however, it was not monomorphic as had previously been reported from the Odisha population of Eastern India. Moreover, contrary to an earlier report that the c.788C>T variant was never found in a homozygous condition, homozygous individuals were found in the European, Asian, Latin American, and Ashkenazi Jews populations.
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