Genome wide association studies have linked a SNP (rs34536443) within <i>TYK2</i> encoding a Proline to Alanine substitution at amino acid 1104, to protection from multiple autoimmune diseases including systemic lupus erythematosus (SLE) and multiple sclerosis (MS).
These findings suggest that the rs34536443 variant effect on multiple sclerosis susceptibility might be mediated by deviating T lymphocyte differentiation toward a Th2 phenotype.
The highest association was at marker rs2304256 (odds ratio (OR) = 0.86; 95%CI = 0.82-0.90) in the TYK2 gene, which has previously been associated with systemic lupus erythematosus and multiple sclerosis.