The known SLE susceptibility genes selected for genotyping included Fcγ receptor 2A (FCGR2A), cytotoxic T-lymphocyte-associated protein 4 (CTLA4), programmed cell death 1 (PDCD1), interferon regulatory factor 5 (IRF5), GTPase, IMAP family member 5 (GIMAP5), and tyrosine kinase 2 (TYK2). Here, TYK2 is linked to systemic lupus erythematosus.