Their research, published in the October edition of the American Journal of Human Genetics, suggests that the suspected risk gene may contribute as much as 30 percent of the underlying genetic cause of ADHD and may also be involved in a separate childhood onset disorder, autism.

Pinpointing a gene with a major role in ADHD will help researchers and clinicians better understand the biology of this disorder and likely lead to the development of improved diagnosis, treatment and early intervention.

We know there are about 35,000 genes in the human genome. By highlighting this region on chromosome 16, we have narrowed our search for a risk gene underlying ADHD to some 100 to 150 genes, said Susan Smalley, principal investigator of the study and co-director of the Center for Neurobehavioral Genetics at the UCLA Neuropsychiatric Institute.

Still, we must wait for independent replication of our results to confirm these findings, said Smalley, also a professor of psychiatry and biobehavioral sciences at the David Geffen School of Medicine at UCLA. Ultimately, we must identify the specific risk gene from among the 100 to 150 genes in this region before we can move to the next level of using such findings to help individuals with ADHD.

By studying families in which there are two or more ADHD siblings, the investigators were able to scan the entire human genome, containing some 35,000 genes, to focus in on specific regions likely to contain a gene contributing to ADHD.

In their initial scan, several regions showed modest support for a risk gene; however, in a follow-up study of one region on chromosome 16, evidence of a risk gene was striking with favorable odds of 10,000 to 1. Surprisingly, independent stu
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Contact: Dan Page
dpage@support.ucla.edu
310-794-2265
University of California - Los Angeles
22-Oct-2002