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Wednesday, October 19, 2011

Zeroing in on the genetic causes of autism

Two groups have created new mouse models of autism spectrum disorder (ASD) diseases by adding or subtracting specific genes or chromosome regions. 

ASD clearly has a very strong genetic component.  Several genes and groups of genes have been implicated in the development of autism, both by identifying genetic changes in people and by replicating those changes in mice.  In particular, copy number (the number of times the same gene is repeated throughout the genome) of some genes seems to be critical for proper brain development.

Researchers from Cold Spring Harbor Laboratory, Stanford, Wharton University and the Hospital for Sick Children, Toronto have been studying a region of chromosome 16 that is often deleted in humans with ASD.  They bred mice with comparable deletions and found that the mice exhibited many behaviors consistent with autism.

Another group from Harvard increased the copy number of a gene (Ube3a) found on chromosome 15.  People with more than the usual number of Ube3a genes display symptoms of ASD.  Mice bred with triple the dosage of this gene exhibited autistic traits, such as repetitive behavior.

Clearly, there is no single cause of ASD. Many genes have been implicated in this disorder, including genes on chromosomes 15, 16 and X.  However, as we study mouse models for the disease, we may be closer to finding treatments.