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08/13/2013
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Group of children with PTEN mutation in the gene that causes some cancers also develop the brain disorder
Draws between autistic children. Scientists see the relationship between genetic mutation and cancer disorder Photo: FRED R CONRAD / NYT
USA - By studying two seemingly unrelated conditions - autism and cancer - researchers converged to an unexpected discovery. Some people with autism have tumor genes apparently cause the brain disorder. Ten percent of children with mutations in a gene called PTEN, which causes breast cancer, colon and other organs also have autism.
- It's weird - says Evan Eichler, professor of Genome Science, University of Washington, on convergence.
He and others caution that the finding applies to a small portion of people with autism. In most cases, the cause remains a mystery. And as with almost all genetic disorders, not everyone with the mutation develop autism or cancer, or other diseases associated with genes, such as epilepsy, brain dilated and benign brain tumors.
But researchers say the finding is intriguing. As there are no animals that naturally initiate a framework of autism, there is no way to analyze what can cause disorder in developing brains nor no cure.
The newly discovered link allowed scientists to examine mice with symptoms of the disorder, which led to the first clinical trial of a potential treatment for children with autism who received drugs to treat tumors with the same genetic background.
Richard Ewing, a boy of 10 years who has a form of autism caused by tumor gene, is among study volunteers. His parents, Rick and Alexandra Ewing, know that it is at risk of developing a brain tumor, heart, kidney, skin and eyes. But the bad news was minimized their eligibility for the clinical trial, which has just begun.
- There is a big difference between us and the rest of the autistic community - says the father. - We have a genetic diagnosis.
Not everyone agrees that the discovery is so promising. Steven McCarroll, Harvard geneticist, points out that autism in children using tumor gene have "a brain that is failing in many ways." Autism in these children may be a manifestation of a malfunction of the brain in general, he said, adding that "the fact that autism is one of many neurological problems that arise in these patients does not necessarily tell us something relevant about the social deficits and language that are specific to the disorder. "
But other scientists not involved in the research say their work is changing our understanding of autism and its development. Like cancer, the disorder involves the irregular growth of cells, in this case, neurons.
The head of the Center for Genome Molecular and Neuropsychiatric Diseases, University of California, Jonathan Sebat, describes the parallel between cancer and autism as "very strange".
- We do not solve everything, only a small part. But this is a very enlightening - he said.
Was Charis Eng, a geneticist at the Cleveland Clinic, who first noticed a surprising incidence of autism in children whose parents had a PTEN mutation. Researchers have realized that the rate of autism was 10%, about 10 times higher than expected.
Tuberous sclerosis also linked to autism
In the same period, scientists discovered another genetic disorder had even more likely to result in autism: tuberous sclerosis, which increases the risk of cancer in kidney and brain. About half of patients with tuberous sclerosis had autism.
Although the genes PTEN and tuberous sclerosis are not the same, they are part of the same network of genes that slow cell growth. Disabling or PTEN genes tuberous sclerosis, this brake is released. The result may be cancer, abnormal nerve fibers or autism.
Mustafa Sahin, Children's Hospital Boston, decided to test whether the drugs used to treat tumors caused by mutation of the gene for tuberous sclerosis may also treat autism in people with the same mutation.
He began the experiment in mice, deleting the genes of the cerebellum. Nerve fibers in the brain of the animal grew wildly, and the animals developed abnormal behaviors resembling autism, such as repetitive movements.
But the substance rapamycin, which targets the lock tuberous sclerosis gene and blocks protein involved in cell division caused improvement in animals which were tested for memory and learning, as well as being greater control of growth of nerve fibers in the brain.
Now Sahin gives a similar drug, the everolimus for autistic children with the genetic mutation. Richard is among children. Each take the drug or placebo for six months. The study is expected to conclude in December 2014.
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Source: The Globe - Online
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This article was translated by an automatic translation system, and was therefore not reviewed by people.