Using Exomechip genotype data available for 3,053 SLE cases and 13,687 controls of European ancestry, we observed that the three RA-protecting TYK2 variants P1104A, A928V, and I684S protected against SLE (Pomnibus = 6x10-18), with effect sizes similar to the effect sizes in RA (Fig 4A). Here, TYK2 is linked to rheumatoid arthritis.