Hereditary multiple exostoses is a familial disturbance in the growth of cartilaginous bone tissue, most marked at the diaphyso-epiphyseal junction of the long bones. Hereditary Multiple Exostoses (Hme) Support Group - NHS Hereditary multiple exostoses and enchondromatosis Resources: Hereditary multiple osteochondromas Hereditary multiple exostoses (HME) is an inherited genetic condition characterized by the presence of multiple exostoses (osteochondromas). A firm nodule develops from beneath the nail bed. Chondrosarcoma transformation in hereditary multiple exostoses: A ... EXT1 and EXT2 have been associated with both familial hereditary exostoses and spontaneous multiple hereditary exostoses. Hereditary Multiple Exostoses This relatively common, highly penetrant, autosomal dominant disorder features irregular bone excrescences that protrude from expanded metaphyses. Diagnosis is made with radiographs showing sessile or pedunculated lesions . Hereditary multiple exostosis | Radiology Case | Radiopaedia.org The big toenail is affected in three-quarters of cases. The gene changes resulting in Multiple Exostoses are fully penetrant (that is, anyone with the gene change has at least mild manifestations of the disease) but markedly variable in expression. Most individuals will have a causal change in one of two genes, EXT1(around 60%) or EXT2 The exostoses are categorized in two ways: sessile or pedunculated. . Hereditary multiple osteochondromas is a rare disorder that affects bone growth. Hereditary multiple exostoses (HME) is an autosomal-dominant disorder characterized by the development of benign tumours, multiple osteochondromas (exostoses), growing outward from the metaphyses of long bones.