Objective: To study association of VDR gene Fok1 polymorphism locus on bone mass accrual in adolescent girls.
Methods: An intervention trial was carried out in 102 girls aged 816 years (Pune, India). All girls received 500 mg elemental calcium (daily) and 30 000 IU of vitamin D3 quarterly for 1 year. Outcome variables were measured at baseline and end of the year. Serum levels of ionised calcium (iCa), inorganic phosphorous, parathyroid hormone (PTH) and 25-hydroxy vitamin-D were measured (25(OH)D). Bone mineral content (BMC), bone area (BA), bone mineral density (BMD) and lean body mass (LBM) were measured at total body by DXA. Percentage increase in BMC, BA and BMD was calculated. Polymorphisms (FF, Ff, ff) of VDR gene at Fok1 locus were detected using SYBR Green quantitative PCR.
Results: Overall prevalence of Fok1 genotypes were 43.1 Ff, 9.8 ff and 47.1% FF. There were no significant differences in percentage change in serum parameters during the intervention period between groups (P>0.05). At baseline, FF genotype had significantly lower BMD as compared to ff and Ff genotype (P<0.05) and significantly lower BA as compared to ff genotype (P<0.05). A significant increase in BMC, BA, BMD and LBM was observed post supplementation in all the three Fok1 polymorphism groups (P value<0.05). However, there were no significant differences in the percentage increase in BMC (Ff (17.9%); ff (18.1%); FF (17.4%)), BA (Ff (11.6%); ff (11.2%); FF (11.8%)), BMD (Ff (5.4%); ff (6.3%); FF (4.9%)) and LBM (Ff (8.4%); ff (9.2%); FF (10.7%)) (P>0.05) (Fig).
Conclusion: Girls with FF genotype had significantly lower bone indices as compared to ff and Ff genotypes. VDR gene polymorphism as defined by Fok1 genotype had no positive influence on bone mass accrual in study girls.
22 Jun 2013 - 25 Jun 2013