IDENTIFICATION AND CHARACTERIZATION OF A NOVEL MEMBER OF THE EXT GENEFAMILY, EXTL2

Recently, two homologous genes, EXT1 and EXT2, with a putative tumor s uppressor function have been described. Mutations in both genes are re sponsible for multiple exostosis syndrome (EXT), an autosomal dominant condition characterized by the presence of multiple osteochondromas, bony excrescences that sometimes undergo malignant transformation to c hondrosarcoma. This family of EXT genes has been extended by the ident ification of an EXT-like (EXTL) gene showing a high degree of homology with the EXT genes. We report here a second EXT-like gene (EXTL2) whi ch is homologous to the EXT and EXTL genes. EXTL2 consists of 5 exons encoding an ubiquitously expressed protein of 330 amino acids. In addi tion, a putative pseudogene, EXTL2P was also identified. The EXTL2 gen e was assigned to chromosome 1p11-p12, whereas EXTL2P was mapped on ch romosome 2q24-q31.