BACKGROUND: Optimal peak bone mass is closely related to sufficient andappropriately timed androgen release. However, attainment of peak bone mass in men, as in women, is undergenetic control, as well as being subject to hormonal and mutational effects. With increasing recognitionof osteoporosis and related fractures in men, it is of interest to consider whether there is relationshipbetween bone density and vitamin D receptor (VDR) polymorphisms, as described in women.
MATERIAL ANDMETHODS: To assess the influence of allelic variation in the VDR gene on vertebral bone density in menwith idiopathic hypogonadrotrophic hypogonadism (IHH), 27 patients (mean age 21.4 +/- 0.4 yrs) and 25age-and-BMI matched healthy males (mean age 21.2 +/- 0.3) were genotyped using three restriction enzymes(Apa I, Bsm I, and Taq I). Vertebral bone mineral density was measured using dual energy X-ray absorptiometry(DEXA).
RESULTS: As expected, vertebral bone density was reduced significantly in patients with IHH (p< 0.001). Despite weak evidence for an association between Apa I polymorphism and vertebral bone densityin the IHH group (r = 0.454, p = 0.017 and r2 = 0.20), VDR genotype was not associated with vertebralbone density in either group. When analyzing homozygous haplotypes, the probability of carrying the favorableBAt haplotype was greater in the control group (OR = 2.000 vs. 0.500).
CONCLUSION: We conclude that VDRgenotype has no influence on vertebral bone density in men with IHH. Thus, allelic variation in the VDRcannot help define those at increased risk for osteoporosis and related fractures among such patients.

Keywords: VDR polymorphism, bone mineral density, IHH