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Ask Dr. K

May 3, 2012

New autism studies yield exciting results

DEAR DOCTOR K: I've heard that scientists have discovered genes that cause autism. Could this lead to a cure?

DEAR READER: Autism is a disorder of child development. Kids with autism have difficulty communicating and forming social relationships.

The studies you are referring to identify genes that increase the risk of autism, and could someday lead to a cure. I think of these studies as the first steps down what is going to be a long road. Nevertheless, they are genuinely exciting.

Three studies were recently published in the scientific journal Nature. Cell samples from 549 families were included. In each family, one child was autistic, but the parents and siblings were not.

Each study determined the sequence of every gene in every individual. Think of a gene as a string of pearls. Each "pearl" is one of four different nucleic acids, which are the building blocks of genes. The sequence of those nucleic acids determines what the effect of the gene will be.

Even 10 years ago such a study would have been impossibly expensive and taken hundreds of years to complete. However, new technologies now make it possible to sequence genes much faster, and for a tiny fraction of the cost.

All three research groups found very strong evidence that the autistic children had suffered serious mutations, or alterations, in at least three specific genes. The studies also found strong evidence of a role for another group of genes.

The mutations were not found in the parents or non-autistic siblings. So the mutations must have occurred in the DNA of the egg or the sperm that created the child with autism.

The studies also indicated that mutations in the father's genes (in the sperm) are more likely to lead to autism than mutations in the mother's genes (in the egg). Furthermore, mutations in the father's genes are more likely as the father gets older.

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