Endocrine Abstracts

Introduction: Polymorphisms of genes involved in the growth process are an important cause of growth hormone deficiency (isolated form). Isolated growth hormone deficiency can be caused by genetic defects in about 10% of patients, in 34% of cases it is a consequence of familial pathology, and 4% are sporadic cases. 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 locatedon chromosome 12q13.1.

Aim: To study the Taql polymorphism of the VDR gene in children with GH-deficiency.

Material and methods: Determination of the Taql polymorphism of the VDR gene (rs731236) was performed in 36 prepubertal GHD children by polymerase chain reaction followed by analysis of the length of the restriction fragments when detected by agarose gel electrophoresis.

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 from1:1, which indicates the preservation of allele frequencies in the Ukrainian population.

Conclusions: A significant number of GHD children (55.56%) have heterozygous T/C genotype of Taql polymorphism (rs731236) against the background of significantly lower levels of IGF-1 and stimulated GH in comparison with these indicators in children carrying homozygous C/C genotype. Hypovitaminosis D was detected in all patients with somatotropic insufficiency: deficiency - in children with homozygous T/T genotype (42.08±15.70 nmol/l), and vitamin D deficiency - in carriers of heterozygous T/C genotype (56.24±18.60 nmol/l) and homozygous C/C genotype (68.25±16.87 nmol/l).