Significant association between Taq1 gene polymorphism in vitamin D receptor and chronic spontaneous urticaria in the Northeast of Iran

Abstract

ObjectiveChronic spontaneous urticaria (CSU) is defined as urticaria with an unknown etiology which persists for more than 6 weeks. CSU is an uncomfortable cutaneous condition that occurs due to an immune-mediated inflammatory reaction. Many studies have demonstrated that vitamin D deficiency and single-nucleotide polymorphisms in the vitamin D receptor (VDR) impact the immune response. In the current study, the frequency of the Taq1 polymorphism in the VDR gene were compared between patients with CSU and individuals without CSU.MethodsIn a case–control study, a group of CSU patients (n = 100) was compared with a group of healthy age- and gender-matched individuals as a control group (n =100) who visited our center between 2015 and 2017. After DNA extraction from EDTA-containing blood, polymerase chain reaction (PCR–RFLP) was used to determine the presence of the Taq1 polymorphism. Serum vitamin D levels were measured using ELISA method (Abcam, Cambridge, USA).ResultsGenotyping for Taq1 polymorphism showed that TT, Tt and tt genes frequency in the CSU group were 36%, 54%, and 10% respectively. The TT, Tt and tt genotypes had a distribution of 50%, 47% and 3% respectively in the control group. The mean serum vitamin D level in the CSU group was 19.88 ± 8.14 ng/ml, which was not significantly correlated with the Taq1 polymorphism (P = 0.841). There was a significant relationship between Taq1 gene polymorphism (tt genotype) and CSU (P = 0.038). Tt genotype increased the risk of CSU (odds ratio = 1.596), and inheritance of tt genotype increased the risk even further (odds ratio = 4.630).ConclusionThe frequency of Taq1 genotype polymorphism in the VDR gene was significantly higher in patients with CSU compared to the control group. The tt genotype polymorphism may be a risk factor for CSU.