Autism: UCSF zeroes in on rare chromosome defect
Friday, March 30, 2012
Christopher Mahar, a 14-year-old from Oregon whose autism may be caused by a rare chromosome defect, prepares for a scan at UCSF to follow his brain activity.
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When her son was diagnosed with a rare chromosome defect three years ago, it was something of a relief for Theresa Mahar.
Finally, she had an explanation. Christopher, now 14, had obvious developmental delays and intellectual disabilities. He had behavior problems and struggled in school. He'd been assigned so many diagnoses over the years - almost all of them related to autism - that it was sometimes hard to keep up.
Then a genetic test revealed the defect to chromosome 16 - one of the 23 chromosomes that make up every person's DNA - and it explained, perhaps, the cause of Christopher's autism.
"It's something to hold on to," Theresa Mahar said. "It's something to blame."
Mahar and her family came to San Francisco from Hillsboro, Ore., this week to participate in an unusual study at UCSF - to map in great detail the brains of people who have a defect to chromosome 16.
The study is one of the first in which autism researchers are narrowing their focus into one of the few known causes of the disorder. That's important, scientists say, because autism is such a difficult condition to define - the symptoms can vary widely from patient to patient, and the causes are often impossible to determine.
Different mechanisms
Autism may be a collection of similar conditions, rather than one single disorder, researchers say. That means that studying patients with autism as it's now defined often produces mixed results - the brain scan of a child with one genetic cause of autism may look very different from the scan of an autistic child with no genetic cause.
"It may be that there are different mechanisms depending on the underlying biology of autism," said Dr. Elliott Sherr, who heads the study at UCSF. "If you study a group and they have the same biology and underlying genetics, in theory that should clean things up a bit."
The study at UCSF is part of a five-center clinical trial funded by the private Simons Foundation. Researchers plan to study at least 200 volunteers with the chromosome 16 defect.
Both Christopher and his father, Robert Mahar, have the same defect. In their case, a tiny section of the chromosome known as the 16p11.2 segment is duplicated. Robert Mahar is not diagnosed with autism, but he struggled in school and now wonders if he had learning disabilities related to chromosome 16.
Scientists were able to identify the connection between the specific chromosome 16 defects and autism using relatively new supersensitive genetic testing tools. Chromosome 16 defects are thought to cause about 1 percent of all cases of autism in the United States, affecting roughly 30,000 children.
On Wednesday and Thursday this week, both Christopher and Robert Mahar had a magnetic resonance imaging (MRI) scan to map the structure of their brains. They also had a magnetoencephalograph (MEG) scan, which follows brain activity and lets scientists see what parts of the brain "light up" when patients are doing certain tasks or thinking about specific topics.
Seeking treatment clues
For example, one problem often associated with autism is an inability to tell faces apart. So Christopher and his father spent several minutes in the MEG scanner looking at pictures of faces while doctors studied their brain activity. The results will be compared with scans of people without the chromosome defect.
Sherr said he hopes the collection of scans from similar patients will paint a clear picture of what happens in the brains of people with this specific defect. Then, scientists can use that information to get a better understanding of what might be causing autism in those patients - and better yet, how it might be treated.
For now, few standard treatments exist for autism beyond behavioral therapy. Some drugs work, but not for everyone, and often not very well. Even the behavioral therapy could be better tailored to the individual patient if doctors better understood what was causing the problem, said Dr. Linda Lotspeich, a psychiatrist with the Autism and Developmental Disorders Clinic at Lucile Packard Children's Hospital at Stanford.
"Those targeted treatments could be more sophisticated behavioral treatments than we currently have, and they could be biological treatments," Lotspeich said.
The Mahars said they don't expect the current research to help their son immediately. It's been frustrating trying to get help for Christopher, Theresa Mahar said. Even finding a doctor who has heard of the chromosome 16 defect has been tough.
Sitting in a conference room at the end of the day Wednesday, the Mahars were exhausted. Christopher and Robert Mahar had been going through tests all morning and afternoon, and Theresa Mahar and the couple's daughter, Caitlin, were stuck at the hospital.
Helping other children
When his last psychiatric evaluation was done, Christopher begged for a toy from the scientists and asked if the family could go to the zoo. Maybe on another trip, Theresa Mahar said - they still had another day of testing before going home.
She said she understands that Christopher may never directly benefit from the research being done now, and Robert Mahar said the goal is to "figure out something for other kids down the road."
"But for my part, participating in this research is being selfish," Theresa Mahar said. "It's about how we can help my son."
Details on disorder
For more information about the chromosome 16 and autism research at UCSF, including how to volunteer for the study, go to links.sfgate.com/ZLIP.
Erin Allday is a San Francisco Chronicle staff writer. eallday@sfchronicle.com
This article appeared on page A - 1 of the San Francisco Chronicle
Read more: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2012/03/29/BAPU1NS5LL.DTL#ixzz1qpeeUA4U
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