We previously reported an association between the SH2D2A gene encoding TSAd and multiple sclerosis (MS). Here a total of 2128 Nordic MS patients and 2004 controls were genotyped for the SH2D2A promoter GA repeat polymorphism and rs926103 encoding a serine to asparagine substitution at amino acid position 52 in TSAd. The GA(16)-rs926103()A haplotype was associated with MS in Norwegians (OR 1.4, P=0.04). A similar trend was observed among Danes. In the independent Norwegian, Danish and Swedish sample sets the GA(16) allele showed a combined OR of 1.13, P=0.05. Thus, the present study shows that the SH2D2A gene may contribute to susceptibility to MS.