Our results also showed that several enzymes that catalyze the biosynthesis of sulfated glycosaminoglycans (GAGs) of proteoglycans, including CHST1, EXTL3 and SLC26A2, were differentially methylated in the advanced stage of human disc degeneration compared to those in the early stage. The gene discussed is SLC26A2; the disease is intervertebral disk degenerative disorder.