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).
SLE protection was associated with TYK2 risk infection variants affecting residually its catalytic domain, rs12720356 (OR = 0.308; p = 0.041) and rs34536443 (OR = 0.370; p = 0.034), but not with rs2304256, rs12720270, and rs280500.
Second, we show that the same three TYK2 variants protect against systemic lupus erythematosus (SLE, Pomnibus = 6 x 10(-18)), and provide suggestive evidence that two of the TYK2 variants (P1104A and A928V) may also protect against inflammatory bowel disease (IBD; P(omnibus) = 0.005).