Vitamin D receptor gene FokI polymorphisms inXuence bone mass in adolescent football (soccer) players

Abstract

The genetic inXuence on bone mineralization during adolescence is unclear possibly due to modifying factors such as skeletal maturation and lifestyle. We evalu ated the inXuence of polymorphisms of the vitamin D receptor (VDR) gene on longitudinal changes in bone mass, bone- and calcium-related hormones in 46 adolescent soc cer players (11.8–14.2 years). Total body bone mineral content (TBMC) and density (TBMD) were measured at baseline and after 6 months. Insulin-like growth factor-I (IGF-1), testosterone, intact parathyroid hormone, and activity of plasma bone alkaline phosphatase were mea sured at baseline and after 3 months. The inXuence of FokI or TaqI VDR genotypes on changes in the outcome vari ables were analyzed by univariate ANOVA with adjust ment for chronological age, skeletal age and body weight at baseline. At baseline, boys with Ff genotype had higher TBMC, TBMD, TBMD Z-score compared to those with FF genotype (P < 0.05). After 3 months, Ff boys also had higher increment in plasma IGF-1 (P < 0.05). FokI poly morphism did not inXuence changes in bone mass measure ments after 6 months, although diVerences detected at baseline remained signiWcant after 6 months. There were no diVerences in the outcome variables according to TaqI genotypes. This study demonstrates that FokI polymor phisms aVect bone mass in Brazilian adolescent soccer players and suggests that the FokI eVect on bone minerali zation occurs during bone maturation, possibly at the initial pubertal stages.