Association of Serum Vitamin D Level with its Receptor Gene Polymorphism BSML in Beta Thalassemia Major Patients from...

Background Vitamin D deficiency is commonly identified in beta thalassemia major patients, related to iron accumulation.Vitamin D mediates its action upon binding to vitamin D receptor (VDR), a classical nuclear receptor. Several single nucleotide gene polymorphisms has been identified in VDR gene among which Bsml is commonly studied for its association with bone mineralisation and osteoporosis. Objective To explore the association between the Vitamin D Receptor Polymorphism (BsmI) and serum levels of Vitamin D, ionised Calcium, alkaline phosphatase in patients with beta thalassemia major. Method VDR gene was studied for Bsml polymorphisms from purified DNA in thirty six beta thalassemic patients (cases) - fourteen male and twenty two females, and thirty three controls after amplification by PCR followed by restriction digestion using appropriate restriction enzymes. Allelic differences between two groups were assessed by chi square and odds ratio test. Any potential link between the polymorphic variations and vitamin D status were assessed by post hoc ANOVA with bonferroni correction among the three genotypes. Result The distribution of BB genotype was significantly higher among the case groups (thalassemic group, χ2 = 9.77, p= 0.008). The odds ratio for the allele B was significantly higher in thalassemia group for a range of 1.97 to 5.94 for 95 percent cofidence interval (χ2 =10.4, p=0.0013). Serum Vitamin D, ionised Calcium were significantly low (p < 0.001) and Alkaline phosphatase (p < 0.001), was significantly high in thalassemics (cases). The genotype BB group had significantly low Vitamin D (p=0.001) and ionised Calcium (p < .001) compared to Bb and bb. The bb genotype had the highest levels of Vitamin D and ionised Calcium among the three genotypes. Conclusion The thalassemic patients are prone to Vitamin D deficiency and the superimposed predominance of BB genotype in them may be a risk factor for osteoporosis and cardiac dysfunction. Moreover, the study indicated genotype bb to have a probable protective role against Vitamin D deficiency in beta thalassemic patients.