| Hereditary multiple exostoses (HME) is an autosomal dominant disease characterized by the formation of cartilage-capped prominences (exostoses) that develop from the juxta-epiphyseal regions of the long bones. Pelvis and ribs are also the most frequently affected bones, vertebrae, sternums, carpus, tarsus are rarely affected. The exostoses are either sessile or pedunculated and they vary widely in size and number. They can be present at birth and continue to appear and grow throughout childhood and into puberty. They can cause multiple and severe complications. The most severe complication is malignant transformation of an exostosis into a chondrosarcoma. The most common clinical problems associated with HME include pain and cosmetic complaints. Additionally, lesions may cause disrupted osseous growth, bowing of the long bones, angulation of the joints, and decreased ranged of joint motion. The most commondeformities described in children with HME include short stature, limb length discrepancies, valgus deformities of the knee and ankle, asymmetry of the pectoral and pelvic girdles, bowing of the radius with ulnar subluxation of the carpus, subluxation of radial head, and relative shortening of the metatarsals, metacarpals, and phalanges. Skeletal defects may lead to associated soft tissue problems, including tendon, nerve, or vascular irritation and injury. Up to now, the sexual mobidity about HME had reported differently, and the pedigrees over five generations also reported rarely, so analyze the loci of exostoses, collect clinical data, find rules, it can be benefit for investigating the genotype-phenotype correlation in HME.Most HME cases are linked to two main loci, EXT1 and EXT2. Both possess the N-acetyglucosamine and D-glucuronic acid transferase activities representative of an HS-polymerase which involved in the catalysis of biosynthesis of heparan sulfate proteoglycans (HSPGs), a key component of cartilage. EXT mutations in HME may act by disrupting the negative feedback loop of chondrocyte differentiation, resulting in abnormal and ectopic skeletal development. EXTL mutation had not found in any HME cases. Except that mutations had found in EXT1 and EXT2, some new mutations may be found in these areas. To detect the pathogenic genes of HME, EXT1 and EXT2 genes in the pedigree have been studied, find novel mutations, which can be good for elucidating the etiology of HME, diagnosing HME inantepartum and genetic counseling.Part oneThe clinical and imaging observation of hereditary multipleexostosisIn this study, two HME pedigrees which have been clinically and pathologically confirmed were studied. Plain X-ray film was performed in all patients. The results are the following: (1) In the 31 patients diagnosed with hereditary multiple exostosis, 16 (51.6%) were male and 15 (48.4%) were female. (2)Their mean age was 38 (5 to 81). 3 patients, who are young and locate in the pedigrees of 4th, 5th generation, had the severest symptomatic lesions. The distribution of symptomatic lesions was analyzed for all patients. The most common location of exostosis was juxta-epiphyseal regions of the long bones. One case was found in pelvis, rib, vertebrae, respectively and three cases were found in scapula. However, none exostosis was found in skull.The present results indicated that There was no gender difference in the incidence of HME and the clinical phenotypes of HME are passed down more severely from generation to generation with the selective feature in the location of exostosis.Part two...
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