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Study: Twins correlated for hallux valgus, but this link may not be due to shared genetics
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An association exists between twins in the development of hallux valgus, but there is no indication that this association is the result of shared genetics, according to recently published findings.
Researchers sent a cross-sectional survey to 74 monozygotic (MZ) and 56 dizygotic (DZ) female twin dyads registered with the Twin Research Program at the Royal Melbourne Hospital.
Investigators found hallux valgus was reported in a total of 70 participants (27%). Of the 130 pairs of twins, concordance of hallux valgus was seen in 19 participants (15%). Twelve (16%) were MZ pairs and seven (12.5%) were DZ pairs. The projected concordance for those with no familial connection was 7%. An unadjusted analysis revealed a casewise concordance of 0.57 for MZ pairs and of 0.50 for DZ pairs. Although these exceeded the 7% expected concordance with no familial association, there was no significant disparity between these findings.
In addition, MZ pairs had a correlation of 0.50 and DZ pairs had a correlation of 0.33, a difference which was not statistically significant. In an analysis that adjusted for the prevalence of hallux valgus for age, twins were found to be correlated and concordant.
Regular use of footwear with a constrictive toe-box in the fourth decade of life correlated with hallux valgus. While this risk factor was correlated in MZpairs, it was not correlated in DZ pairs. A significant difference was noted in these correlations.
[We] confirmed that [hallux valgus] HV is a familial condition, but found no evidence that this association was due to genetic factors. We also found that the key equal environments assumption of the classic twin model did not apply to a newly identified risk factor for this condition, bringing into doubt previous estimates of heritability based on that model,” the researchers wrote. “Our finding that shared environmental factors are important in the risk of HV, and that the use of footwear with a constrictive toe-box during the fourth decade of life is a specific environmental risk factor, could be particularly important.” – by Jennifer Byrne
Disclosure s : The researchers report no relevant disclosures.
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