Association between vitamin D receptor polymorphisms and multiple sclerosis： systematic review and meta-analysis of case-control studies

Vitamin D receptor （VDR） polymorphisms have been studied as potential contributors to multiple sclerosis （MS）. However, published studies differ with respect to study design and the significance of the effects detected. The aim of this study was to quantify the magnitude of the risk associated with the Taql, Bsml, Apal and Fold VDR polymorphisms in MS using a meta-analysis approach. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we conducted a systematic search and meta-analysis of the literature. Subgroup analyses were performed to detect potential sources of heterogeneity from the selected study characteristics. The stability of the summary risk was evaluated using sensitivity analyses. The meta-analysis included a total of 3300 cases and 3194 controls from 13 case- control studies. There were no significant associations found between Taql and Bsml polymorphisms and MS risk. The association between the Apal polymorphism and MS risk was significant in the homozygous and codominant models （P=0.013 and P=0.031, respectively）, suggesting that the AA Apal genotype might be a significant MS risk factor. Publication year and age significantly affected the association between Taql polymorphisms and MS （P=0.014 and P=0.010, respectively）, which indicates a protective effect of the major T allele. The AA Apal and FF Fold genotypes are significant risk factors for MS. The association between the Taql polymorphism and MS risk is significantly affected by study characteristics.

Characterization of Wheat Random Amplified Polymorphic DNA Markers Associated with the H11 Hessian Fly Resistance Gene

In Tunisia, the Hessian fly Mayetiola destructor Say is a major pest of durum wheat （Triticum durum Desf.） and bread wheat （T. aestivum L.）. Genetic resistance is the most efficient and economical method of control of this pest. To date, 31 resistance genes, designated H1-H31, have been identified in wheat. These genes condition resistance to the insect genes responsible for virulence. Using wheat cultivars differing for the presence of an individual Hessian fly resistance gene and random amplified polymorphic DNA （RAPD） analysis, we have identified a polymorphic 386-bp DNA marker （Xgmib1-1A.1） associated with the H11 Hessian fly resistance gene. Blast analysis showed a high identity with a short region in the wild wheat （T. monococcum） genome, adjacent to the leaf rust resistance Lr10 gene. A genetic linkage was reported between this gene （Lr10） and Hessian fly response in wheat. These data were used for screening Hessian fly resistance in Tunisian wheat germplasm. Xgmib1-1A.1-like fragments were detected in four Tunisian durum and bread wheat varieties. Using these varieties in Hessian fly breeding programs in Tunisia would be of benefit in reducing the damage caused by this fly.