Well Being

Chromosome 16 and a Test for Autism?

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Researchers from the University of New South Wales report on a new way to detect autism earlier by studying the connectivity of the brain; it is hoped that, by incorporating psychological and biological factors in assessing young children, autism might be detected earlier. Another way to screen for autism in young children—-and even in children prior to birth—would be via genetic testing. Last week, scientists in the New England Journal of Medicine published a study about the deletion or duplication of chromosome 16 and susceptibility to autism. A January 18th Toronto Star article the family of 11-year-old Joshua Bond, who has autism and who is missing chromosome 16 (Joshua was involved in the study at The Hospital for Sick Children).

The next step, already underway at Sick Kids, is to develop a simple and inexpensive DNA test that can pinpoint duplications or deletions on chromosome 16. Right now, autism is diagnosed by assessing a child's behaviour and social communication skills, an often difficult and labour-intensive process, says Rosanna Weksberg, a clinical geneticist and head of clinical and metabolic genetics at Sick Kids.

A DNA test performed as soon as a child exhibits some symptoms could catch autism quickly and early, she says. Studies have shown early intervention, especially when an infant's brain is still developing, can diminish some symptoms.

The promise of genetic tests also raises ethical considerations that researchers are just starting to sort out. For example, how would a potential prenatal DNA test for chromosome 16 mutations be used in family planning?Wendy Roberts, a developmental pediatrician and co-director of the Autism Research Unit at Sick Kids, says even a DNA test of parents would be valuable for predicting the chances of their next child having autism. If the parents do not test positive for the mutation, the likelihood of a second child testing positive is no higher than in the general population, she says. And she knows there is demand for it; the hospital is already fielding calls from parents who have heard about the mutation and want the test.

“If they thought there would be a test available within a year, most (parents wanting another child) would wait that long,” she says.

Today's New York Times has a cautionary article about the rapid increases in genetic testing and of tests that are marketed directly to consumers. Eye on DNA reviews a study in the New England Journal of Medicine that gives direct-to-consumer genome scans a thumb down. But what about any genetic tests for autism, especially if these are performed when a child is still in utero?

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