assigning its extracellular localization. The large number of introns suggests that genetic recombination may contribute to the instability of the gene, leading to diseases such as SVAS. The expression of tropoelastin mRNA is highly regulated under at least eight different transcription start sites. Tissue specific variants of elastin are produced by alternative splicing of the tropoelastin gene. There are at least 11 known human tropoelastin isoforms. these isoforms are under developmental regulation, however there are minimal differences among tissues at the same developmental stage. See also Cutis laxa Elastic fibers Elastin receptor Resilin: an invertebrate protein Williams syndrome References Further reading External links GeneReviews/NIH/NCBI/UW entry on Williams or Williams-Beuren Syndrome The Elastin Protein Microfibril Aging-related proteins Biomaterials Elastomers Extracellular matrix proteins Structural proteins