WHAT CAUSES DE NOVO AUTISM? The father's increasing age is the major cause of de novo mutations in the population.

- Despite its reputation as the most highly heritable of all neuro-psychiatric diseases, autism appears in families with no history of the disorder. A new study led by Michael Wigler and Jonathan Sebat at Cold Spring Harbor Laboratory provides evidence that the sporadic, non-inherited form of autism may be genetically distinct from heritable autism. Published in “Science Express,” these findings may influence future autism research and diagnostic testing.

Using new high resolution array technology to detect mutations, Sebat and colleagues found that spontaneous deletions and duplications of genetic material, so-called copy number variation, were ten times more prevalent in sporadic cases of autism spectrum disorders than in healthy control subjects They found the spontaneous mutations in 14 of 195 people with autism spectrum disorders compared to two of 196 unaffected individuals. The results also implicate the anomalies as primary, rather than just contributory, causes of the disorder in most cases when they are present, according to the researchers.


"Our results show conclusively that these tiny glitches are frequent in autism, occurring in at least ten percent of cases, and primarily in the sporadic form of the disease, which accounts for 90 percent of affected individuals," said study co-author Jonathan Sebat. " But since each mutation is individually rare–few were seen more than once–the results suggest that many different sites in the genome likely contribute to autism. Therefore, although the presentation of various forms of autism may be similar, any combination of variations of 100 or more genes may be responsible.