Hereditary multiple exostoses (HME) is a skeletal disorder characterized by the development of multiple benign cartilage-capped bone tumors (osteochondromas), typically arising from the metaphyses of long bones during childhood. Affected individuals may develop skeletal deformities, limb-length discrepancies, pain, restricted joint mobility, and have a small lifetime risk of malignant transformation to chondrosarcoma.

This panel currently includes EXT2, a key gene involved in heparan sulfate biosynthesis and normal growth plate development. Pathogenic variants in EXT1 and EXT2 are the major causes of hereditary multiple exostoses, and the absence of EXT1 from this panel should be considered when interpreting a negative result.

This panel is recommended for patients with a clinical diagnosis or strong suspicion of hereditary multiple exostoses, particularly when multiple osteochondromas are present without features suggestive of a broader skeletal dysplasia. Because EXT1 is not included, additional testing may be warranted in appropriate clinical settings.