pseudoachondroplasia

A skeletal dysplasia characterized by short-limb dwarfism with leg deformities associated with genu varum or genu valgum and ligamentous laxity, allowing the joints to telescope; normal appearing head and face. Autosomal dominant inheritance [MIM*177150 and MIM*177170] caused by mutation in the cartilage oligomeric matrix protein gene (COMP) on 19p. SYN: pseudoachondroplastic spondyloepiphysial dysplasia.

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pseu·do·achon·dro·pla·sia (soo″do-a-kon″dro-plaґzhə) [pseudo- + achondroplasia] an autosomal dominant osteochondrodysplasia caused by mutation in the COMP gene (locus: 19p13.1), which encodes cartilage oligomeric protein, important for organization of collagen fibers in the extracellular matrix of chondrocytes. It is a form of dwarfism in which limbs are short but head size and facial features are normal; there are knee and other skeletal deformities and joint hypermobility, and osteoarthritis beginning in early adulthood. The mutation is allelic with that causing one of the forms of multiple epiphyseal dysplasia (q.v.).