EXT2 and hereditary multiple exostoses: Multiple hereditary exostoses (MHE), also known as hereditary multiple exostoses (HME), is a dominant, autosomal hereditary multifocal rare condition most commonly associated with mutations in two genes, exostosis-1 (EXT1) and exostosis-2 (EXT2), identified in 70-94% of cases, with a prevalence rate of 1 in 50,000 [1-4].