Aggrecanases are known to be responsible for aggrecan degradation in articular cartilage in diseases such as OA and rheumatoid arthritis (RA) [13], and cleave the aggrecan core protein at several specific sites; one is between Glu373 and Ala374 which generates the G1-NITEGE fragment [14,15]. The gene discussed is ACAN; the disease is rheumatoid arthritis.