No evidence of association of the rare nsSNP rs35667974 in IFIH1 with multiple sclerosis

Studies suggest that different autoimmune diseases share a common genetic background, in particular, an overlap between Multiple Sclerosis (MS) and type 1 diabetes (T1D) susceptibility loci has been established. A recent study found that four rare SNPs in the IFIH1 (interferon induced with helicase C domain 1) were significantly associated with T1D.To establish if these SNPs were also involved in MS susceptibility, we chose to examine the non-synonymous SNP rs35667974/Ile923Val which displayed the strongest effect in T1D and was also shown to lead to a loss of IFIH1 function in an in vitro study. We have performed the first association study to test if this rare variant is involved in MS susceptibility in a very large sample consisting of 3037 MS patients and 10,657 healthy controls recruited from Italy and the UK. This study has 99% power to demonstrate an association at the 5% level with this rare variant. Our analysis shows that the nsSNP rs35667974/Ile923Val does not have a role in susceptibility to MS.