Any multiple epiphyseal dysplasia in which the cause of the disease is a mutation in the COL9A3 gene. The disease is epiphyseal dysplasia, multiple, 3 (MONDO_0010964, a Monarch Disease Ontology identifier). Also known as: COL9A3 multiple epiphyseal dysplasia (disease), epiphyseal dysplasia, multiple, 3, with or without myopathy, epiphyseal dysplasia, multiple, type 3, multiple epiphyseal dysplasia (disease) caused by mutation in COL9A3.