Parathyroid hormone (PTH) plays a crucial role in calcium metabolism and skeletal development via altering vitamin D level. Besides, hypersecretion of PTH is implicated in the etiology of osteoporosis. In this study, we analyzed association between promoter region sequence variants of PTH gene and circulating 25-hydroxy-vitamin D (25(OH)D) level. Genotypes of PTH SNPs rs1459015, rs10500783 and rs10500784 and circulating serum 25(OH)D level of healthy adults (N=386) of different nationalities living in Riyadh were determined and relation between the different PTH allelic variants and corresponding mean 25(OH)D values were obtained using Analysis of Variance (ANOVA) and Bonferroni post-hoc test for multiple comparisons. We observed a high prevalence of vitamin D deficiency (<50 nmol/l) among all nationals which ranged from 59% among Indians to 82% among Yemeni. Comparison of the means of 25(OH)D levels corresponding to different genotypes of PTH SNPs indicated that the T allele of SNP rs1459015 was associated with higher 25(OH)D level in the Sudanese (P=0.03), while the T allele of SNP rs10500783 was associated with higher 25(OH)D level in Saudis (P=0.03). Analysis of results also indicated that the Sudanese carriers of the CC genotype of SNP rs1459015 had a higher risk of suffering from vitamin D deficiency (P=0.02). In conclusion, our study indicated significant association between specific PTH gene promoter region variants and altered levels of 25(OH)D and vitamin D deficiency among specific nationals.
Keywords: 25(OH)D; Parathyroid hormone; osteoporosis; single nucleotide polymorphism; vitamin D.