Evaluation of Vitamin D Receptor Taq I (rs731236) and Bsm I (rs1544410) Gene Polymorphisms in Patients with Chronic Kidney Disease-mineral and Bone Disorder

Abstract

BACKGROUND: Chronic kidney disease-mineral and bone disorder (CKD-MBD) is one of the main culprits of increasing morbidity and mortality in patients with stage: 3–5 CKD. Association between Vitamin D receptor (VDR) genetic polymorphisms and CKD-MBD has been inconsistent. AIM: The aim of the study was to assess the association of VDR Taq I (rs731236) and Bsm I (rs1544410) gene polymorphisms with CKD; and with the development and progression of CKD-MBD. METHODS: Sixty adult (43–56 years.) Egyptian CKD-MBD male patients (CKD stages: 3–5 with estimated glomerular filtration rate <60 mL/min 1.73 m2) and 30 matched-pair healthy controls were recruited from Theodor-Bilharz Research Institute. Bsm I and Taq I polymorphisms of VDR gene were assessed using restriction fragment length polymorphism-polymerase chain reaction. RESULTS: CKD-MBD patients having Taq I “tt” mutant gene had a significant decrease in serum 25 hydroxy Vitamin D and a significant elevation of plasma intact parathyroid hormone levels. Having the homotypic “tt” gene variant of VDR Taq I increased the susceptibility to CKD-MBD (Odds ratio [OR]: 19.6, CI: 4.3–89.9 p < 0.01) compared to having the wild “TT” or heterotype “Tt” genotype. Moreover, presence of VDR Taq I “tt” genotype increases OR of having 25 hydroxy Vitamin D deficiency in CKD-MBD patients 7.25 times (CI = 2.21–23.80; p < 0.01). CONCLUSION: VDR Taq I (rs731236) “tt” genotype increases the susceptibility to CKD-MBD development and progression in Egyptian CKD patients. Moreover, the presence of Taq I “tt” genotype in CKD-MBD patients is independently associated with the risk of developing Vitamin D deficiency.