Sacroiliac erosion and fusion have typically been characterized in ankylosing spondylitis (AS) patients, and studies published before 2012 reported higher DKK1 expression; however, contradictory results have since emerged, and a comprehensive meta-analysis found no association of serum DKK1 with AS (Wu et al., 2018). The gene discussed is DKK1; the disease is ankylosing spondylitis.