Gal-9 and its receptor, T cell immunoglobulin domain and mucin domain-3 (Tim-3), are able to induce apoptosis of T cells in the pathogenesis of RA by regulating immune responses by T helper type 1 (Th1) and T helper type 17 (Th17) cells9–11. The gene discussed is HAVCR2; the disease is rheumatoid arthritis.