Article

Identification of twelve mutations in cartilage oligomeric matrix protein (COMP) in patients with pseudoachondroplasia.

Department of Pediatrics, University of Texas Medical School at Houston, 77225-0708, USA.
American Journal of Medical Genetics (Impact Factor: 3.23). 01/1999; 80(5):510-3. DOI: 10.1002/(SICI)1096-8628(19981228)80:53.0.CO;2-F
Source: PubMed

ABSTRACT Pseudoachondroplasia (PSACH) is an autosomal dominant dwarfing condition characterized by disproportionate short stature, joint laxity, and early-onset osteoarthrosis. PSACH is caused by mutations in the gene encoding cartilage oligomeric matrix protein (COMP). We are reporting on mutations in COMP in 12 patients with PSACH, including ten novel mutations. Eleven of the mutations are in exons 17A, 17B, and 18A, which encode the calcium-binding domains, and one mutation is in exon 19, which encodes part of the carboxy-terminal globular domain. Two of the mutations identified are the common delGAC(1430-1444) in exon 17B, which accounts for 36% of identified PSACH mutations. This report increases the range of mutations in COMP that cause PSACH and provides additional evidence for the importance of the calcium-binding domains and the globular domain to the function of COMP.

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    ABSTRACT: Pseudoachondroplasia (PSACH) is a skeletal dysplasia characterized by disproportionate short stature, small hands and feet, abnormal joints and early onset osteoarthritis. PSACH is caused by mutations in thrombospondin-5 (TSP-5, also known as cartilage oligomeric matrix protein or COMP), a pentameric extracellular matrix protein primarily expressed in chondrocytes and musculoskeletal tissues. The thrombospondin gene family is composed of matricellular proteins that associate with the extracellular matrix (ECM) and regulate processes in the matrix. Mutations in COMP interfere with calcium-binding, protein conformation and export to the extracellular matrix, resulting in inappropriate intracellular COMP retention. This accumulation of misfolded protein is cytotoxic and triggers premature death of chondrocytes during linear bone growth, leading to shortened long bones. Both in vitro and in vivo models have been employed to study the molecular processes underlying development of the PSACH pathology. Here, we compare the strengths and weaknesses of current mouse models of PSACH and discuss how the resulting phenotypes may be translated to clinical therapies.