Collagen Type X is associated with hypertrophic chondrocytes of avian and mammalian growth plate tissues during the endochondral growth of long bones. It is a component of normal articular cartilage in adult human, growing pig and newborn rat, and it is also present during any disruption of normal metabolic status of articular cartilage that occur with osteoarthritis. Collagen Type X is composed of three identical a 1 (X) chains, each containing a triple-helical region flanked by a short N-terminal sequence and a larger non-collagenous C-terminal (NC1) domain. Mutations in COL10A1, the gene encoding for Collagen Type X, are associated with metaphyseal dysplasia type Schmid (SMCD) and other related forms of metaphyseal dysplasia. SMCD is characterized by short-limbed dwarfism, an outward "flaring" of the lower rib cage, bowed legs, leg pain and a hip deformity that causes the thigh bone to angle toward the center of the body.