Because BTLA was relatively recently described in the literature, there are only a few studies that address BTLA gene polymorphisms, and most have investigated its role in susceptibility to autoimmune diseases, such as rheumatoid arthritis (Lin et al. 2006; Oki et al. 2011), systemic lupus erythematosus and type 1 diabetes mellitus (Inuo et al. 2009) and only one in risk of cancer (Fu et al. 2010). Here, BTLA is linked to systemic lupus erythematosus.