Boys are diagnosed with autism spectrum disorder (ASD) 10 times more often than girls. So-called “classic autism” affects boys four times more often than girls.
Researchers are investigating the causes of autism and of this disparity between the sexes. Recent research published in Molecular Psychiatry and headed up by Dr. Stanley Nelson, professor of human genetics at the David Geffen School of Medicine at UCLA, focuses on the role that the gene CACNA1G plays in autism. Funding for the study was provided by the National Institute of Mental Health and Cure Autism Now, which has since merged with Autism Speaks.
Nelson explains the study’s findings: “We found that a common form of the gene occurs more frequently in the DNA of families that have two or more sons affected by autism, but no affected daughters. Our study may explain why boys are more susceptible to the disorder than girls.”
The research team studied the DNA of 1,046 members of families in which at least two sons were diagnosed by autism, looking for common gene variants: genes in which subtle changes have occurred.
“We wanted to identify what was happening in this region of Chromosome 17 that boosts autism risk,” said Nelson. “When the same genetic markers kept cropping up in a single region of the DNA, we knew we had uncovered a big clue.”
The gene CACNA1G, which helps move calcium between the cells, has a common variant that appears in the DNA of nearly 40 percent of the population.
“This alternate form of CACNA1G consistently increased the correlation to autism spectrum disorder, suggesting that inheriting the gene may heighten a child’s risk of developing autism,” observed Nelson. While the gene cannot be considered, on its own, a risk factor for autism, what is not known is the role the gene plays in a higher risk of autism.
Nelson concedes that “We need a larger sample size to identify all of the genes involved in autism and to solve the whole puzzle of this disease.”
In order to help solve the puzzle, the UCLA team will sequence the gene in people with the variant form to identify the exact change that increases autism risk.
While identifying autism on the genetic level carries with it its own set of moral and ethical conundrums, one thing is clear: early diagnosis and intervention can significantly help those with autism diagnoses. Increased research into risk factors for autism may help researchers to diagnose autism at an earlier age. Autism is usually diagnosed around age 3. Since early intervention and treatment are crucial in helping those affected lead normal lives, early identification is equally crucial.