A population-based study of IL4 polymorphisms in multiple sclerosis.

Previous studies have suggested a role for interleukin-4 gene (IL4) in susceptibility to multiple sclerosis (MS) as well as other autoimmune diseases. We screened the promoter region, exons 1-4 and their splice sites for polymorphisms and tested the association between novel polymorphisms E1(33)*C-->T and I3(2580)*C-->A, and the established 5'(-523)*C-->T and I3(709)*VNTR polymorphisms with susceptibility to, age of onset in, and course and severity of MS in sporadic cases. I3(709)*VNTR was associated with susceptibility to MS (p=0.004) due to a dearth of heterozygotes in patients (29/122; 23.8%) compared to controls (91/244; 37.3%). Homozygotes for the uncommon I3(709)*allele-2 may have increased susceptibility (p=0.044; OR=5.17, 95% CI: 0.83-54.95) as might carriers for the extended haplotypes 5'(-523)*T/E1(33)*T/I3(709)*allele-2/I3(2580)*C (p=0.003; OR: 3.75, 95% CI: 1.18-11.93) or 5'(-523)*C/E1(33)*C/I3(709)*allele-1/I3(2580)*A (p=0.004; OR: 4.22, 95% CI: 1.22-14.54). We could not confirm the previously reported association between carriage of I3(709)*allele-2 and older age of onset. However, we found a trend for association between the homozygous state for this allele and older age of onset.