Exostosin-2 is one of two glycosyltransferases involved in the chain elongation step of heparan sulfate biosynthesis. Mutations in this gene cause the type II form of multiple exostoses.By positional cloning and use of a chromosome 11-specific fetal brain cDNA library, Stickens et al. (1996) identified the putative EXT2 gene, which was predicted to encode a 718-amino acid protein with a molecular mass of 82 kD. Both protein and DNA sequence-based algorithms detected significant similarity with the product of the EXT1 gene, suggesting that the 2 genes are evolutionarily and functionally related. Northern blot analysis detected a major 3.5-kb mRNA transcript and a minor band of 3.7 to 4.0 kb in most tissues.EXT2 gene may be expressed as a complex set of alternatively spliced forms.