Asporin, ASPN belongs to a family of leucine-rich repeat (LRR) proteins associated with the cartilage matrix. The name asporin reflects the unique aspartate-rich N terminus and the overall similarity to decorin.Higher levels in osteoarthritic articular cartilage, aorta, uterus. Moderate expression in small intestine, heart, liver, bladder, ovary, stomach, and in the adrenal, thyroid, and mammary glands. Low expression in trachea, bone marrow, and lung.
Variation in the poly-Asp region of ASPN is associated with osteoarthritis susceptibility type 3 (OS3) ; also known as osteoarthritis of knee/hip. Osteoarthritis is a common disease that produces joint pain and stiffness together with radiologic evidence of progressive degeneration of joint cartilage.