DNA link to autism uncovered
PARIS: Three new studies have identified DNA links to rare and common forms of autism, spotted among genes involved in forging connections between brain cells, scientists reported on Tuesday.
The evidence strengthens suspicions of a genetic role in autism spectrum disorders (ASD), the term for an array of conditions ranging from poor social interaction to repetitive behaviors and entrenched silence, they said.
The three investigations, reported online by the British-based journal Nature, looked for tiny genetic mutations among thousands of people with ASD and people who were otherwise healthy.
In the biggest search, conducted among 10,000 people, a team led by Hakon Hakonarson, a professor at the University of Pennsylvania School of Medicine, shed light on a stretch of DNA between two genes called CDH9 and CDH10, located on Chromosome five.
The two genes produce a protein called cadherin, which allows cell surfaces to adhere to each other.
The researchers also found that a group of about 30 genes, which encode cell adhesion proteins, including cadherin and a cousin protein called neurexin, were strongly associated with ASD.
Cell adhesion proteins play a vital role in the developing brain, allowing neurons to migrate to the correct places and connect with other neurons.
ASD has triggered a fierce debate about the cause, ranging from exposure in the womb to the male hormone testosterone, environmental factors after birth and genetic factors, including "sporadic," or accidental, mutations as opposed to inherited ones that are passed down through generations.
"There are going to be many genes involved in causing autism," Hakonarson said in a press release issued by the US National Institute of Neurological Disorders and Stroke (NINDS).
"In most cases, it's likely that each gene contributes a small amount of risk, and interacts with other genes and environmental factors to trigger the onset of disease."
AFP
(China Daily 04/30/2009 page11)
