Vitamin D level, lipid profile, and vitamin D receptor and transporter gene variants in sickle cell disease patients from Kurdistan of Iraq

Abstract

Introduction: Sickle cell disease (SCD) patients are susceptible to the development of vitamin D deficiency (VDD). Vitamin D through binding to vitamin D receptor (VDR) exerts its function and affects gene transcription in target tissues. VDR gene variants affect bone mineral density. Methods: In a case-control study, 101 SCD patients including 61 sickle cell anemia (SCA), 39 S/β-thalassemia, and 1 HbS/HbD (SD) along with 110 healthy individuals from Kurdistan of Iraq were studied. The lipid profile, vitamin D level, FokI, and TaqI variants of VDR and group-specific component (GC) were detected using the standard enzymatic method, the immunodiagnostic systems limited EIA kit and PCR-RFLP methods, respectively. Results: Around 93% and 82% of SCA and S/β-thalassemia patients, respectively, had VDD compared to 83% of healthy individuals. Severe VDD (<10 ng/ml) was detected in 78.7% of patients with HbSS. Plasma levels of total cholesterol, HDL-C, and LDL-C in SCD patients were significantly lower compared to controls. Vitamin D levels were negatively correlated to TG and positively correlated to total cholesterol and HDL-C. The frequencies of the C allele of FokI were 81.7% (p = 0.003), 80.3% (p = 0.034), and 84.6% (p = 0.011) in all SCD, SCA, and S/β-thalassemia patients, respectively, compared to 69.1% in controls. However, no significant difference was detected comparing the frequencies of VDR TaqI and GC polymorphisms between SCD patients and controls. Conclusion: In the present study, we found hypocholesterolemia, high prevalence of VDR FokI C allele, and low vitamin D levels among children and adults with SCD from Kurdistan of Iraq.