Type 2 deiodinase Thr92Ala polymorphism is associated with a reduction in bone mineral density: A community-based korean genome and epidemiology study

Abstract

Objective: Type 2 deiodinase (DIO2)-mediated thyroid hormone synthesis stimulates osteoblast activity and increases the expression of osteoblast differentiation markers, but there are no large cohort studies to identify the role of the DIO2 polymorphism in bone mineral density in humans. Methods: To investigate the hypothesis that individuals with the DIO2 gene polymorphism are susceptible to osteoporosis, we assessed the polymorphism of the DIO2 gene in 7,524 Koreans drawn from the large-scale Ansan-Anseong cohort of the Korean Genome and Epidemiology Study. All of the participants underwent genotyping of the DIO2 Thr92Ala polymorphism (rs225014). Results: A total of 6,022 participants were recruited; 1991 (33.0%) were homozygous for the Thr allele, 2,967 (49.3%) were heterozygous (Thr/Ala), and 1064 (17.7%) were homozygous for the Ala allele. The effects of the DIO2 Thr92Ala polymorphism on axial speed of sound (SOS) and the T-score in the tibia and radius were assessed, with age, gender, oestrogen status, body mass index (BMI), serum calcium, 25-hydroxyvitamin D, and parathyroid hormone (PTH) included as covariables. Female subjects carrying the DIO2 Thr92Ala polymorphism had significantly lower SOS and T-scores than control participants. Cox regression analysis revealed a significant relationship between the DIO2 polymorphism and diagnosis of osteoporosis in female participants. Conclusion: DIO2 Thr92Ala polymorphism is associated with decreased SOS and T-scores in the tibia of female subjects independent of other clinical parameters, where this indicates a potential functional role of DIO2 in the maintenance of bone mineral density.