The finding in a subset of osteochondromas of cytogenetic aberrations, mainly 8q deletions, as well as biallelic inactivation of the EXT1 (located in 8q24) or EXT2 (located in 11p11) gene in cells of the cartilage cap supports a neoplastic nature of the tumors (1). The gene discussed is EXT2; the disease is Osteochondroma.