Effect of age, gender and calciotropic hormones on the relationship between vitamin D receptor gene polymorphisms and bone mineral density

Abstract

Background/Objectives: Hypovitaminosis D is a major public health problem worldwide and unexpectedly more so in sunny countries. Vitamin D receptor (VDR) gene is associated with inter-individual variance in bone mineral density (BMD). Studies assessing the effect of VDR gene polymorphisms on BMD yielded conflicting results. The aim of this study was to assess the relationship between VDR polymorphisms and BMD in the Lebanese, across age groups and genders and to assess the effect of PTH and lean mass and vitamin D levels on such relationship. Subjects/Methods: In total, 203 subjects aged 65-85 years and 336 children aged 10-17 years. Polymorphisms in the VDR gene were assessed with the restriction enzymes BsmI, TaqI and ApaI. Bone mineral content, BMD and lean mass were measured using Dual-Energy X-ray Absorptiometry (DXA). The dominant hand strength was measured in children. Results: Heterozygote genotype was the most frequent in both age groups. There was no difference in the frequency distribution of genotypes between the young and the elderly. No relationship between VDR genotypes and lean mass was found in either age group. Heterozygote boys had the lowest parathormone (PTH) and heterozygote elderly women had the highest BMD at the spine and forearm. Conclusions: In the Lebanese, the relationship between VDR polymorphisms and BMD differs by age. Survival does not seem to differ by VDR genotype. However, further studies are needed to assess the effect of VDR gene polymorphisms on mortality per se and time to mortality, not evaluated in this study.

Vitamin D status in relation to obesity, bone mineral density, bone turnover markers and vitamin D receptor genotypes in healthy Saudi pre- and postmenopausal women

“…Allele and VDR genotypes frequencies obtained among Saudi pre-and postmenopausal women were very similar to that reported in other Caucasian [57][58][59] and Arabian [28,62] women with AG genotype being the most common. No differences were obtained in BMD values or BTMs among the genotypes; which is similar to previous reports [63][64][65][66][67] and controlling for serum 25(OH)D and/or menopausal status did not influence these findings.…”

Генетический Полиморфизм Рецептора Витамина D Определяет Его Метаболизм И эффективность

“…Однако значение полиморфизма гена РВД остает-ся неясным, противоречивым, вариабельным в зави-симости от пола, возраста, этнической группы, роста костной массы, ассоциации с паратгормоном, влия-ния кальция, образа жизни и уровня здоровья [19].…”

“…Тем более эти результаты отличаются при их сравнении на фоне бо-лее низкой МПКТ в Индии по сравнению с жителями Северной Америки или Европы [17]. [19].…”

Vitamin D and bone health outcomes in older age

“…The relationship of circulating blood levels of 25(OH)D to PTH is contentious. Some studies suggest that PTH reaches a plateau with increasing serum 25(OH)D concentration (62,63) , while others demonstrate an inverse relationship throughout the physiological range of 25(OH)D concentrations (45,(64)(65)(66)(67) . It is important to consider that the relationship between 25(OH)D and PTH may be influenced by the effects of many other factor including co-morbidities.…”

“…It is important to consider that the relationship between 25(OH)D and PTH may be influenced by the effects of many other factor including co-morbidities. advancing age, dietary Ca and phosphate intake, renal function, plasma vitamin-Dbinding protein, Mg concentration, IGF-1, testosterone, smoking and physical inactivity which may all have important roles in the development of secondary hyperparathyroidism (45,64,(66)(67)(68) . Moreover, comparisons between studies may be hampered by the use of different assays for 25(OH)D and PTH (69,70) .…”