Abstract: SA-PO912

Influence of Vitamin D Receptor Polymorphisms on Biochemical Markers of Mineral Bone Disorders in South African Patients with CKD

Session Information

  • Mineral Disease: CKD-Bone
    November 04, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Mineral Disease

  • 1203 Mineral Disease: CKD-Bone

Authors

  • Waziri, Bala, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, Gauteng, South Africa
  • Naicker, Saraladevi, University of the Witwatersrand, Johannesburg, Gauteng, South Africa
Background

It remains unclear whether genetic factors may explain the reported variation in the levels of biochemical markers of chronic kidney disease mineral and bone disorders (CKD- MBD) across ethnic groups. Therefore, the aim of this study was to examine the influence of VDR polymorphisms on secondary hyperparathyroidism and its association with vitamin D levels in black and white South African study participants.

Methods

This was a cross sectional study involving 272 CKD stage 3- 5D patients and 90 healthy controls. The four common VDR polymorphisms (Bsm 1, Fok 1, Taq 1, and Taq 1) were genotyped using the polymerase chain reaction- restriction fragment length polymorphism (PCR –RFLP) method. In addition, the biochemical markers of CKD- MBD were measured to determine their associations with the four VDR polymorphisms.

Results

With the exception of Taq I polymorphism, the distribution of the VDR polymorphisms differs significantly between blacks and whites. In hemodialysis patients, the Bb genotype was significantly associated with moderate secondary hyperparathyroidism (OR, 0.3.12; 95 CI 1.11-8.83, p=0.03) and severe hyperparathyroidism (OR, 2.55; 95 CI 1.19-5.47, p=0.02). This was consistent with the observed higher levels of median PTH and mean phosphate in patients with Bb genotype. This candidate risk genotype (Bb) was over represented in blacks compared to whites (71.0 % versus 55.6 %, p <0.0001). In an unadjusted regression model, Fok Ff genotype was found to be significantly associated with the risk of developing severe vitamin D deficiency < 15ng/ml (OR, 1.89; 95 CI 1.17-3.07, p=0.01 ).

Conclusion

The VDR Bb genotype is an independent predictor of developing secondary hyperparathyroidism in patients with end stage renal disease. In addition, study participants with the Fok Ff genotype are at increased of developing severe 25(OH) D deficiency