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DNA Markers in Low-IQ Autism Suggest Heredity

July 5, 2013
A possible biomarker

Eric Morrow, lead author Ece Gamsiz, and colleagues analyzed the DNA of 2,100 autistic children in families where neither parents nor siblings were affected. Autistic children with significant intellectual disability had long “runs of homozygosity” — strands of identical DNA from both parents. Credit: Mike Cohea/Brown University

Researchers, including graduate students Emma Viscidi and Abbie Frederick, are striving to understand the different genetic structures that underlie at least a subset of autism spectrum disorders. In cases where the genetic code is in error, did that happen anew in the patient, perhaps through mutation or copying error, or was it inherited? A new study in the American Journal of Human Genetics finds evidence that there may often be a recessive, inherited genetic contribution in autism with significant intellectual disability.

The authors also make predictions in the study regarding how far back in the history of the family the disease-associated variants may have occurred. It’s far.

The research team led by Eric Morrow, assistant professor of biology in the Department of Molecular Biology, Cell Biology, and Biochemistry at Brown University, made its findings by analyzing the DNA of more than 2,100 children with autism who were born into “simplex” families where neither their parents nor a sibling has an autism disorder — a Simons Foundation data set known as the Simons Simplex Collection. The researchers combed through the genomes of affected children and their siblings for so-called “runs of homozygosity” — long strands of DNA in which the genetic material contributed by both the mother and the father turn out to be the same.

Read more of the article about DNA markers by David Orenstein.