New Genetic Mutation Found Associated with Autism
Autism, which affects about one in 110 children in the United States, has no known or established cause, but new research from Princeton University and Penn State College of Medicine may have uncovered two genes that may be involved.
Senior author Daniel Notterman MD, professor of pediatrics, biochemistry and molecular biology at Penn State, says that their new findings adds to the growing evidence that there are genetic links for autism, but does not rule out a role for environmental causes.
"Over the last couple of years, beginning in 2007, it's become clear that some cases of autism, maybe up to 15%, will be caused by rare mutations, either occurring spontaneously or that can be inherited by a parent," he says.
Notterman and study co-author Ning Lei PhD of Princeton analyzed data from the Autism Genetic Resource Exchange (AGRE) on 943 families, most of whom had more than one child diagnosed with autism and had undergone genetic testing.
The researchers compared the prevalence of 25 gene mutations between the study group as compared to a control group of over 6,300 individuals without developmental or neuropsychiatric illness. They then narrowed their focus on four genes, two of which are already known to be associated with autism because they are involved in forming or maintaining neural synapses.
One of the new genes identified by the research, presented at the Pediatric Academic Societies (PAS) annual meeting in Vancouver on May 2, is called Neural Cell Adhesion Molecule 2, or NCAM2. This gene is expressed in the hippocampus and the cerebellum of the brain, regions associated with autism.
The genetic mutation of NCAM2 is probably rare, Notterman says. "We would estimate that 0.5% or fewer of kids with autism have the NCAM2 [mutation]."
"While mutations in the NCAM2 gene were found in a small percentage of the children that we studied, it is fascinating that this finding continues a consistent story -- that many of the genes associated with autism are involved with formation or function of the neural synapse," Dr. Lei said. "Studies such as this provide evidence that autism is a genetically based disease that affects neural connectivity."
The study also showed that family members of children with autism may carry the NCAM2 mutation, but do not have the disorder themselves, indicating other environmental or genetic factors are involved.
A second gene, called PTPRD, was also found to be associated with autism, however Notterman said “We are more confident about NCAM2 and less about PTPRD.”