Increased expression of CXCL12–CXCR4 has been identified in a number of diseases such as systemic lupus erythematous (SLE), ankylosing spondylitis (AS), osteoarthritis, mycosis fungoid (MF) and Inflammatory bowel disease (IBD) (Maj et al., 2015; Schimanski et al., 2011; Xu et al., 2007). The gene discussed is CXCL12; the disease is ankylosing spondylitis.