Association of FTO genotype with obesity and bone health among community-dwelling adults ; Goto Island study on bone health

Abstract

Bone mass is tuned by various factors, including aging, menopause, low body weight, and genetic variations. Here, we showed an independent association between a genotype on the fat mass- and obesity-associated FTO gene (#610966 on OMIM) and bone loss after adjusting for age and body mass index (BMI). A cross-sectional study was nested in a prospective observational study of 1,828 participants (median age: 69 [62-76] years in men and 68 [61-75] years in women) residing in a rural city in western Japan (Goto Island study). Participants were recruited during medical checkups in 2014 and 2016 from the community-dwelling population. The bone mass of the calcaneus was evaluated using quantitative ultrasound. The single nucleotide polymorphism (SNP) rs1421085 was genotyped using a hydrolysis probe. The chi-squared test was used to deter-mine whether the variants were in equilibrium in this population. There were differences in medians of BMI among the geno-types (24.3 in CC, 23.0 in CT, and 22.6 in TT, P = 0.01), but not in those of bone mass. There was a significant association between the minor allele (C) and being overweight in a gene dosage-dependent manner (BMI > 25, OR per allele =1.52, 95% CI = 1.07-2.14, P = 0.02 in men, OR = 1.48, 95% CI = 1.16-1.95, P = 0.01 in women). Logistic regression analysis showed a significant protective association in male carriers of the minor allele against low bone mass (QUS T-score less than -2.0) after adjusting for age and BMI in men aged 65-75 years (OR = 0.50, 95% CI = 0.27-0.96, P = 0.036), with no significant association in women.