Genetic variants in IL2RA and IL7R affect multiple sclerosis disease risk and progression

Multiple sclerosis (MS) is a common demyelinating neurodegenerative disease with a strong genetic component. Previous studies have associated genetic variants in IL2RA and IL7R in the pathophysiology of the disease. In this study, we describe the association between IL2RA (rs2104286) and IL7R (rs6897932) in the Canadian population. Genotyping 1,978 MS patients and 830 controls failed to identify any significant association between these variants and disease risk. However, stratified analysis for family history of disease and disease course identified a trend towards association for IL2RA in patients without a family history (p = 0.05; odds ratio = 0.77) and a significant association between IL7R and patients who developed progressive MS (PrMS) (p = 0.002; odds ratio = 0.73). Although not statistically significant, the effect of IL2RA (rs2104286) in patients without a family history of MS indicates that the genetic components for familial and sporadic disease are perhaps distinct. This data suggests that the onset of sporadic disease is likely determined by a large number of variants of small effect, whereas MS in patients with a family history of disease is caused by a few deleterious variants. In addition, the significant association between PrMS and rs6897932 indicates that IL7R may not be disease-causing but a determinant of disease course. Further characterization of the effect of IL2RA and IL7R genetic variants in defined MS subtypes is warranted to evaluate the effect of these genes on specific clinical outcomes and to further elucidate the mechanisms of disease onset and progression.