Genes responsible for autism disorders

Washington: Genetic screening of at-risk patients may lead to better diagnosis or treatment of autism, a study led by an Indian-origin researcher suggests.

As autism spectrum disorders affect nearly 1 in 88 kids, understanding the altered genetic pathways is critical for diagnosis and treatment.

“Autism is the most inheritable of neurodevelopmental disorders, but identifying the underlying genes is difficult since no single gene contributes more than a tiny fraction of autism cases,” Rajini Rao of Johns Hopkins University in Baltimore, Md. said.
Rather, she continues, “mutations in many different genes variably affect a few common pathways.”

A team of scientists at Johns Hopkins and Tel Aviv University in Israel looked at genetic variations in DNA sequence in the ion transporter NHE9 and found that autism-associated variants in NHE9 result in a profound loss of transporter function.

“Altering levels of this transporter at the synapse may modulate critical proteins on the cell surface that bring in nutrients or neurotransmitters such as glutamate,” Rao said.

“Elevated glutamate levels are known to trigger seizures, possibly explaining why autistic patients with mutations in these ion transporters also have seizures,” she added.

A unique aspect of the team’s approach was that they exploited decades of basic research done in bacteria and yeast to study a complex human neurological disorder.
First, the group at Tel Aviv University, led by Nir Ben-Tal, built structural models of NHE9 using a bacterial relative as a template, allowing the Rao laboratory at Johns Hopkins to use the simple baker’s yeast for screening the mutations.

In the future, as genomic information becomes readily available for everyone, such easy, inexpensive, and rapid screening methods will be essential to evaluate rare genetic variants in autism and other disorders.


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