Structural component of hyaline cartilage and vitreous of the eye. Defects in COL9A2 are the cause of multiple epiphyseal dysplasia type 2 (EDM2). EDM is a generalized skeletal dysplasia associated with significant morbidity. Joint pain, joint deformity, waddling gait, and short stature are the main clinical signs and symptoms. EDM is broadly categorized into the more severe Fairbank and the milder Ribbing types. EDM2 inheritance is autosomal dominant. Defects in COL9A2 may be a cause of susceptibility to intervertebral disc disease (IDD); also known as lumbar disk herniation (LDH). IDD is one of the most common musculo-skeletal disorders and the predominant cause of low-back pain and unilateral leg pain. Defects in COL9A2 are the cause of Stickler syndrome type 5 (STL5). An autosomal recessive form of Stickler syndrome, an inherited disorder that associates ocular signs with more or less complete forms of Pierre Robin sequence, bone disorders and sensorineural deafness. STL5 is characterized by high myopia, vitreoretinal degeneration, retinal detachment, mild to moderate sensorineural hearing loss, short stature in childhood, and absence of cleft palate and Pierre Robin sequence. Belongs to the fibril-associated collagens with interrupted helices (FACIT) family. Note: This description may include information from UniProtKB.