Smith-Magenis Syndrome Traced to Single Gene Mutation

A study has shown that the retionic acid induced 1 (RAI1) gene located on chromosome 17p11.2 is responsible for the developmental disorder known as Smith-Magenis syndrome (SMS). The study was published March 24, 2003, in the online edition of Nature Genetics.

SMS, which occurs in approximately one of every 25,000 births, is a chromosome microdeletion syndrome characterized by a distinct series of physical, developmental and behavioral features, including varying levels of mental retardation, cranio-facial abnormalities, sleep disturbances and self-injurious behaviors.

Since SMS is normally associated with a chromosomal deletion that includes many genes, it was assumed that more than one gene contributed to the disorder. However, in the current study investigators from Michigan State University (East Lansing, USA) found that the syndrome could be traced to the mutation of a single gene.

"The result of this mutation is that the protein cannot be formed properly,” explained senior author Dr. Sarah Elsea, an assistant professor in the departments of pediatrics and human development and zoology at Michigan State University. "Individuals with SMS have one normal functioning RAI1 protein from one chromosome, but from the other chromosome they are not getting this protein function at all. I think that in the future, if we understand what this gene, this protein, does and how it interacts with other proteins in the cell, we might be able to develop some kind of drug therapy that might help deal with the behaviors a little better.”



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