There was up‐regulation of SLAM family receptors, CD229 and of CD352 (NTB‐A, SLAMF6) in T cells from patients with SLE compared with healthy controls.17 However, among the 11 SLE patients studied, there was a lower correlation between expression and disease severity for CD229 compared with CD352.17 The association between CD229 expression levels and SLE susceptibility is not straightforward. Here, LY9 is linked to systemic lupus erythematosus.