TaqI polymorphism of the vitamin D receptor gene in children with growth hormone deficiency

Abstract

Background. The nuclear receptor for vitamin D mediates most of the biological functions of this vitamin. It belongs to the steroid hormone receptor family, the gene for which (vitamin D receptor — VDR) is located on chromosome 12q13.1. Genetic variability has been reported in the VDR gene, in which more than 470 single nucleotide polymorphisms have been identified. One of the most common polymorphisms in the VDR gene is rs731236 (TaqI). The purpose was to study the TaqI polymorphism of the VDR gene in children with growth hormone deficiency (GHD). Materials and methods. The TaqI polymorphism of the VDR gene (rs731236) was determined using the polymerase chain reaction, followed by analysis of the length of restriction fragments detected by agarose gel electrophoresis in 28 prepubescent children with GHD. Results. In the group of patients with GHD, the proportion of heterozygotes for T/C TaqI polymorphism of the VDR gene (rs731236) is 1.28 times higher than among healthy individuals. There were 0.68 and 0.90 times fewer patients carrying T/T and C/C genotypes than in the control group. The presence of a homozygous TT genotype increases the risk of developing GHD, but not significantly (odds ratio (OR) = 1.89, 95% confidence interval (CI) 0.66–5.39; p = 0.23), and the presence of a homozygous CC genotype is protective (OR = 0.75, 95% CI 0.17–3.22; p = 0.70). When analyzing alleles in patients with GHD, the following data were obtained: carriage of the T allele for the polymorphic loci TaqI rs731236 of the VDR gene is associated with the risk of GHD (OR = 1.24, 95% CI 0.65–2.36; p = 0.52) but not significantly. The ratio of allele (pТ = 0.554, qС = 0.446) frequencies practically does not differ from 1 : 1, which indicates the preservation of allele frequencies in the Ukrainian population. Conclusions. In children with GHD, the proportion of the T/C genotype is 1.28 times higher than in the group of healthy persons. The presence of a homozygous TT genotype increases the risk of developing GHD but not significantly (OR = 1.89, 95% CI 0.66–5.39; p = 0.23). Carriage of the T allele for the polymorphic locus TaqI rs731236 of the VDR gene is associated with the risk of the growth hormone deficiency (OR = 1.24, 95% CI 0.65–2.36; p = 0.52) but not significantly.