Exostoses Like Protein 2 (EXTL2)

In patients with multiple exostoses, mutations in 2 different genes have been found: EXT1 on 8q and EXT2 on 11p. In addition, linkage has demonstrated a third locus, EXT3, on 19p as the site of mutations causing multiple exostoses. The family of EXT genes was extended by the identification of an EXT-like gene (EXTL1) showing a high degree of homology with the EXT genes.EXTL2 was found to consist of 5 exons encoding a ubiquitously expressed 330-amino acid protein. In addition, a putative pseudogene, EXTL2P, was identified. By Northern blot analysis, they detected a 3.4-kb transcript in all tissues tested except leukocyte, where the gene was hardly transcribed. Its expression was relatively constant among tissues, but was weak in liver, lung, and thymus.