Studies regarding the genetic variations of BTLA have mainly focused on its role in cancer (for example, lymphocytic leukemia [27] and breast cancer [28]) and susceptibility to autoimmune diseases (for example, rheumatoid arthritis [29, 30], systemic lupus erythematosus and type 1 diabetes mellitus [31]). The gene discussed is BTLA; the disease is systemic lupus erythematosus.