A rare functional variant within the TYK2 gene (rs34536443) has been reported as protective in multiple sclerosis (MS) in recent studies. However, because of the low frequency of the minor allele (minor allele frequency=0.04), genome-wide significant association has been hard to establish. We genotyped 5429 Nordic MS cases and 6167 healthy controls for this TYK2 non-synonymous single-nucleotide polymorphism (ns-SNP), and combined the Nordic genotype data with raw genotypes from previous studies. The combined Nordic analysis showed significant association with MS (P=5 x 10(-4), odds ratio (OR) 0.78), and by mega-analysis of 10 642 MS patients, 10 620 controls and 2110 MS trios, the association at genome-wide significance level (P=5.08 x 10(-9), OR 0.77) was shown.
