Background: The genetic polymorphisms of vitamin D receptor (VDR) have an association with thalassemia development, additionally to the environmental elements that elicited the disorder in the genetically predisposed individuals. As well, VDR functions responsible for the regulation of bone metabolism, such its part in immunity. Aim: The sitting study intended to inspect the association between thalassemia disease and the genetic polymorphisms of VDR among the Iraqi population then compared these findings to other findings of thalassemia patients in other different ethnic populations. Materials and methods: The restriction enzymes Bsm-I and Fok-I were applied to determine the genetic polymorphisms frequencies of VDR by a Polymerase Chain Reaction – Random Fragment Length Polymorphisms (PCR-RFLP) techniques of the targeted parts (rs2228570 and rs1544410) in 70 Iraqi patients suffering from thalassemia (18 males and 52 females) and 75 Iraqi healthy participants as a control group (18 males and 52 females). Also, the comparison between the present findings of VDR genetic polymorphisms in Iraqi thalassemia patients and other previous findings for thalassemia patients in different ethnic populations for the selected VDR Bsm-I and Fok-I sites were done. Results: The present findings manifested a significant difference of VDR Bsm-I and Fok-I genetic polymorphisms frequency (rs2228570 and rs1544410) in the thalassemia patient's group contrasted to the healthy control group. In VDR rs2228570, the AA genotype and A allele frequency were significantly increased in the patients' group contrasted to the healthy control group (44.29 vs. 8.0%, OR: 9.14, 95% CI: 3.53–23.68, p: 4.1 × 10−7; 69.0 vs. 27.0%, OR: 6.02, 95% CI: 3.27–11.06, p: 3.9 × 10−9, respectively). while, the results of VDR genetic polymorphisms rs1544410 manifested that the CC and CT genotyping and C allele frequency were significantly increased among the patient's group contrasted to the healthy control group (28.75 vs. 6.67%, OR: 5.60, 95% CI: 1.98–15.81, p: 7.2 × 10−4; 57.14 vs. 24.0, OR: 4.22, 95% CI: 2.08–8.55, p: 8.1 × 10−5; and 57.0 vs. 19.0%, OR: 6.39, 95% CI: 3.0–10.66, p: 3.9 × 10−9, respectively). Also, it manifested the genetic polymorphisms variance of VDR rs2228570 and rs1544410 between the Iraqi thalassemia patients and other ethnic thalassemia patients. The results showed different variants among the Iraqi thalassemia patients' polymorphisms and other ethnic thalassemia patients' polymorphisms. Conclusions: The present results demonstrated a significant association between the genetic polymorphisms of VDR and thalassemia disease, the AA genotype and A allele frequency was significantly increased among the thalassemia patients' group compared to the controls in VDR Bsm-I polymorphism (rs2228570). While the CC and CT genotypes and C allele frequency were significantly increased among the thalassemia patients' group compared to the controls in VDR Fok-I polymorphism (rs1544410). As well, it indicates the variance of VDR Bsm-I and Fok-I genetic polymorphisms frequencies between the Iraqi thalassemia patients and other thalassemia patients from different ethnic populations.
