COL9A1 and vitreoretinal degeneration: The main clinical characteristics of individuals affected with biallelic COL9A1 variants include moderate-to-severe sensorineural hearing loss, moderate-to-high myopia with vitreoretinopathy, and epiphyseal dysplasia, whereas COL9A2 variants are associated with high myopia, vitreoretinal degeneration, retinal detachment, hearing loss, and short stature.