Association of genetic polymorphisms in vitamin D receptor (ApaI, TaqI and FokI) with vitamin D and glycemic status in type 2 diabetes patients from Southern India

Abstract

Objectives To evaluate the association of VDR polymorphisms (FokI, TaqI and ApaI) with vitamin D levels and glycemic status in type 2 diabetes patients from Southern India. Methods In this observational study, genotype frequencies and vitamin D levels of 200 cases (type 2 diabetes patients) were compared with 300 controls (unrelated anonymised stored samples of healthy volunteers) from south India. Serum 25 (OH) D levels were measured by immunoassay technique, glycated hemoglobin (HbA1c) was measured using HPLC and genotyping of VDR polymorphisms were carried out using Real time Polymerase Chain Reaction (RT PCR). Results About 69.2% of type 2 diabetes patients were found to have vitamin D deficiency. FokI polymorphism showed variations in serum 25 (OH) D levels, with AA and AG genotypes having significantly lower serum 25 (OH) D levels as compared to GG [13.24 (8.4) ng/ml, 15.02 (7.07) ng/ml and 20.67 (13.64) ng/ml respectively]. There was no difference in HbA1c levels with respect to the vitamin D levels and VDR polymorphisms. Conclusions AA and AG genotypes of FokI polymorphisms are associated with low serum 25 (OH) D levels. However there was no association between VDR polymorphisms and glycemic status in south Indian type 2 diabetes patients.

Impact of vitamin D receptor polymorphisms in selected metabolic disorders

“…Another study indicates that the T allele of the rs7975232 is associated with the onset of T2D, while the G allele can be regarded as a protective allele [22]. On the other hand, other studies have not shown a relationship between rs7975232 genotypes and T2D [23][24][25].…”

“…Another published paper indicates that individuals with T2D and the C allele of rs2228570 may have an increased risk of periodontitis [28]. In contrast, some investigations show no significant association between rs2228570 and T2D [23,29] or glycemic status [23,39]. Also, a study in Malaysian patients with T2D with good or poor glycemic control indicated that rs2228570 was not associated with T2D.…”

“…A study in a small group of patients with T2D indicates that the T allele of rs731236 may be associated with T2D [22]. Another indicates that rs731236 is not related to glycemic status [23,25,39] but may be related to vitD insufficiency in the South African population [39].…”