Influence of genotype and perioral musculature on maxillary and mandibular development.

Objectives: To determine whether there is an association between skeletal jaw position and perioral musculature, and if genotypes can predict skeletal growth.

Materials and methods: A prospective study on 42 patients over 1 year was performed. The study included 22 females and 20 males with and average age of 28.5 years. Lip strength was compared to radiographic cephalometric measurements. Allelic and genotypic frequencies from polymorphisms rs678397 and rs1815739 in ACTN3 and rs10850110 in MYO1H were compared to each variable. Chi-square and Fisher exact tests were used to determine if differences were statistically significant (alpha = 0.05).

Results: The data showed significant differences between rs678397 genotype and allele frequencies and SNA angle (P = .01; P = .003, respectively); between rs1815739 allele frequency and SNA angle (P = .01); between rs678397 allele frequency and ANB angle (P = .049); between rs678397 genotype and allele frequencies and lip strength in females (P = .045; P = .02); and between rs678397 allele frequency and overall lip strength (P = .049), after mean strength values used as cut off being customized by sex.

Conclusions: Polymorphisms in ACTN3 are associated with weak lips and larger SNA and ANB angles.