Plain language summary
Vitamin D is a vitamin that is involved in several immune processes within the body. It acts on immune cells through binding to vitamin D receptors (VDR) and modulating their activity. However genetic variations in VDRs is apparent amongst individuals, with the four most common being TaqI, ApaI, FokI and BsmI. The presence of any of these variations has been associated with the development of several different diseases. This systematic review and meta-analysis aimed to determine whether any of these variations in the VDR was associated with the development of Hashimoto’s thyroiditis (HT), a disease whereby the immune system does not recognise and attacks the body’s own tissues. The results showed that only the FokI variation was associated with the development of HT and only in individuals with Asian heritage. It was concluded that the FokI variation of the VDR is associated with an increased risk of HT in Asians but not Caucasians, however how this occurs is not fully understood. This study could be used by healthcare professionals to understand that genetic variations on the VDR may be indicative of risk of developing HT in individuals from Asian descent.
Abstract
Four VD receptor (VDR) gene polymorphisms (TaqI, ApaI, FokI and BsmI) have been reported to influence Hashimoto's thyroiditis (HT) risk. However, individual studies have produced inconsistent results. We conducted a comprehensive meta-analysis of eleven case-control studies to better understand roles of the four polymorphisms in HT development. The results showed only FokI polymorphism was significantly associated with the risk of HT (F vs f: OR = 1.44, 95% CI = 1.09-1.91, P = 0.010; FF vs Ff + ff: OR = 1.72, 95% CI = 1.09-2.70, P = 0.019). Subgroup analyses demonstrated the significant effect was only present in Asian population (F vs f: OR = 1.45, 95% CI = 1.07-1.95, P = 0.016; FF vs ff: OR = 1.64, 95% CI = 1.03-2.59, P = 0.036; FF + Ff vs ff: OR = 1.34, 95% CI = 1.00-1.80, P = 0.047; FF vs Ff + ff: OR = 1.64, 95% CI = 1.03-2.64, P = 0.039), but not in Caucasian. For TaqI, ApaI and BsmI polymorphisms, no significant association was found in any model comparison. Based on the current literature, it appears that only VDR FokI polymorphism is associated with HT risk in Asian population, but not in Caucasians; and the TaqI, ApaI and BsmI polymorphisms have not positive association neither in the overall population, nor when stratified by ethnicity. Further well-designed studies with larger sample sizes and different ethnic population are needed to clarify the present findings.
Methodological quality
Jadad score
:
Not applicable
Allocation concealment
:
Not applicable
