Prevalence and functional significance of 25-hydroxyvitamin D deficiency and vitamin D receptor gene polymorphisms in Asian Indians.
BACKGROUND
Recent studies show a wide prevalence of hypovitaminosis D in Asian Indians.


OBJECTIVE
The objective was to assess the functional significance of 25-hydroxyvitamin D [25(OH)D] deficiency, vitamin D receptor (VDR) gene, and parathyroid hormone (PTH) gene polymorphisms in relation to bone mineral density (BMD) in urban Asian Indians.


METHODS
Serum total calcium, inorganic phosphorus, alkaline phosphatase, 25(OH)D, intact PTH, and BMD at lumbar spine, proximal femur, and forearm were measured in 105 adult subjects. The genotyping related to VDR (BsmI, FokI, and TaqI) and PTH (BstBI and DraII) gene single-nucleotide polymorphisms was carried out by polymerase chain reaction-restriction fragment length polymorphism analysis.


RESULTS
The mean serum 25(OH)D concentration in the whole cohort was 9.8 +/- 6.0 ng/mL, which was inversely related with serum intact PTH values (P = 0.042). Ninety-nine (94.3%) of the 105 subjects had vitamin D deficiency with 25(OH)D concentrations < 20 ng/mL. The age- and body mass index (BMI)-adjusted BMD value at the hip was higher in subjects with serum 25(OH)D values > 9.0 ng/mL than in those with values < or = 9.0 ng/mL (0.893 +/- 0.114 compared with 0.839 +/- 0.112 g/cm2, respectively; P = 0.001). The mean forearm and spine BMD values in subjects with TT (VDR, TaqI) or bb (PTH, BstBI) genotypes were significantly higher than the values in subjects with Tt genotype and BB or Bb genotype, respectively.


CONCLUSIONS
Functionally significant 25(OH)D deficiency affecting BMD at the hip region is prevalent in urban Asian Indians. However, variation in BMD at the spine and forearm is related to VDR and PTH gene polymorphisms rather than to vitamin D status, at least in this hypovitaminotic D population.
Vupputuri
Madhava Rao
MR
Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, India.
Goswami
Ravinder
R
Gupta
Nandita
N
Ray
Debarti
D
Tandon
Nikhil
N
Kumar
Neeta
N
D000328:Adult; D015992:Body Mass Index; D005260:Female; D005838:Genotype; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D010281:Parathyroid Hormone / Q000235:genetics*; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D015995:Prevalence; D018167:Receptors, Calcitriol / Q000235:genetics*; D014505:Urban Population; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000453:epidemiology*
D010281:Parathyroid Hormone; D018167:Receptors, Calcitriol; D014807:Vitamin D; C104450:25-hydroxyvitamin D