Genetic Influence of ACTN3 Gene Polymorphism rs1815739 on Skeletal Class II Malocclusions with Mandibular Retrognathism

Abstract

ntroduction: Skeletal Class II malocclusion with mandibular retrognathism is a prevalent dentofacial anomaly influenced by both genetic and environmental factors. The ACTN3 gene, which plays a critical role in skeletal muscle structure and function, has been proposed to affect craniofacial growth.

Objectives: This study evaluated the association between the ACTN3 gene polymorphism   rs1815739 (C>T) and skeletal Class II malocclusion with mandibular retrognathism in an Indian population.

Methods: A case-control study was conducted involving 90 subjects aged 20 ± 1.5 years,                      comprising 45 individuals with skeletal Class II malocclusion (cases) and 45 with normal mandibular development (controls). Mandibular retrognathism was assessed using the SNB angle on lateral cephalograms. Genomic DNA was extracted from peripheral blood samples, and genotyping for rs1815739 was performed using Restriction Fragment Length Polymorphism-Polymerase Chain Reaction (RFLP-PCR). Statistical analyses included Chi-square test, odds ratio calculation, and Hardy-Weinberg equilibrium assessment.

Results: Genotype distribution in the control group was CC (22%), CT (46.7%), and TT (31.1%), whereas the case group showed CC (11.1%), CT (64.5%), and TT (24.4%). Allele frequencies for the C and T alleles were 0.45 and 0.55 in controls and 0.43 and 0.57 in cases, respectively. No statistically significant association was found between the rs1815739 polymorphism and skeletal Class II malocclusion (p > 0.05).

Conclusion: The findings indicated that no statistically significant association between the ACTN3 gene SNP rs1815739 and the skeletal Class II malocclusion with mandibular retrognathism, suggesting that rs1815739 is unlikely to be a major contributing factor in its etiology in the Indian population.