Pseudoachondroplasia (pseudoachondroplasia) - Gen COMP.
Pseudoachondroplasia is an inherited disorder of bone growth. It is believed to be related to another disorder of bone growth called achondroplasia, but without the characteristic facial features of the disease. All affected individuals have short stature. The average height of adult males with this disorder is 120 centimeters, and the average height of adult women is 116 centimeters. This feature is not evident at birth, but, however, from two years old, his growth rate falls below the standard growth curve. Other features of the disease include short arms and legs, a contoneado walk, joint pain in childhood, evolving in osteoarthritis, hyperextensibility hands, knees and ankles and a limited range of motion in the elbows and hips . Some individuals have legs directed outward or inward. Sometimes, one leg swings out and the other inwardly. Some affected people have scoliosis or lordosis.
This process is due to mutations in the gene cause COMP, located on the short arm of chromosome 19 (19p13.1). This gene encodes a protein that is essential for normal cartilage development and for conversion to bone. The most cartilage is subsequently converted into bone, cartilage except that covers and protects the ends of bones and is present in the nose and external ears. This protein is normally found in the spaces between the cartilage - forming cells called chondrocytes, which interacts with other proteins.
They have been identified about 60 mutations in the gene causing pseudoachondroplasia COMP. COMP mutations cause gene results in production of an abnormal protein that can not be transported outside the cell, accumulating inside chondrocytes and ultimately leading to early cell death. The premature death of chondrocytes prevents normal growth of bones , causing bone abnormalities observed in the disease. A particular mutation is found in about 30 percent of affected individuals. The D469del 469delD or mutation results in the deletion of a single amino acid called aspartic acid, in the COMP protein. Most other mutations in the gene involve substitution of one amino acid for another amino acid in the protein COMP. Mutations in the gene also result in accumulation of the protein COMP in the endoplasmic reticulum and eventual death of chondrocytes.
Pseudoachondroplasia is inherited as an autosomal dominant, which means that a copy of the altered gene in each cell is sufficient to cause the disorder. In some cases, an affected person inherits the mutation from an affected parent. Most cases result from new mutations in the gene and occur in people with no history of disease in your family.
Tests in IVAMI: in IVAMI perform detection of mutations associated with pseudoachondroplasia, by complete PCR amplification of exons COMP gene, and subsequent sequencing.
Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).