Osteoarthritis (OA) is the most common degenerative jointdisease.In 1999, two members of the A Disintegrin and Metalloproteinase withThrombospondin Motifs (ADAMTS) family of metalloproteinases, ADAMTS4and ADAMTS5, or aggrecanases, were identified as the enzymes responsiblefor aggrecan degradation in cartilage. The gene discussed is ACAN; the disease is osteoarthritis.