Because of the association short-HAVCR1 with RA, a Th1- and Th17-mediated disease, and long-HAVCR1 with atopy, a Th2-mediated disease, it is likely that the HAVCR1 156ins/del in exon 4 are capable of polarizing immune responses. The gene discussed is HAVCR1; the disease is rheumatoid arthritis.