Chromosome 16 and a Test for Autism?

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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    • chrisd

      I suppose it would have prepared us somewhat for what we would be expecting. But will it freak people out who don’t need to be?

    • VAB

      I don’t know if early intervention justifies it. If it’s not something you can notice without testing, early intervention may be overkill. Not everyone on the spectrum needs any “intervention” at all. If it is something that is clear early on, then the tests may be superfluous, especially if, as is currently the case, they are inconclusive. As for the in utero stuff — give me a break, with the goosestepping eugenics.

    • Kristina Chew, PhD

      The mention in the article of people contacting the hospital to find out if there is a test based on the NEJM study stood out to me. I’m not sure they are aware of the implications of such a test—-the “goosestepping eugenics” VAB points out.

    • Morgan

      We did pre-conception genetic testing for cystic fibrosis.

      There is a huge difference between an almost certainly fatal genetic condition and autism, but I don’t regard our precaution as “goosesteping eugenics” — so how should I judge people who approach a genetic predisposition to autism with the same care?

      I abhor the thought of aborting fetally diagnosed autistics, but . . . is there a sensible place to draw the ethical line?

      I wonder. . . .


    • Phil Schwarz

      Judy Badner, a longtime member of Autism Network International, and for several years its science advisor, is a professor of psychiatry at my alma mater, the University of Chicago. She studies the genetic underpinnings of psychiatric conditions and disorders.

      She has a personal background that involves a bit of the drama and controversy over discovery of genetic markers for various conditions, and their subsequent use and abuse: she has achondroplasia, a form of dwarfism.

      In the mid-1990s, a single-gene marker for achondroplasia was discovered. This prompted the national self-advocacy organization of people with achondroplasia and other forms of dwarfism, the Little People of America, to issue a well-reasoned position statement on the use and abuse of genetic research and testing.

      Several years ago, Judy adapted the LPA’s position statement for research into the genetics of autism, and applications of that research. It is equally well-reasoned.

      It can be found here.

    • RAJ

      Microdeletions of chromosome 16P.11 is not an ‘autism’ gene. It has previously been reported in a host of neurological disorders, primarily mental retardation, but also in schizophrenia, ADHD, early onset epilepsy, and in people without any neuropsychiatric diagnosis.

      The problem with the AGRE data is that they don’t segregate findings by IQ and cannot differentiate between a rare mental retardation syndrome and autism. Since AGRE only accepts families who members have an ASD diagnosis, they are looking at an unrepresentative population, only those who have enough ‘autistic type symptoms’ to qualify for a diagnosis. The AGRE dataset does not include the larger population of people with microscopic 16P11 anomolies who may have some ‘autistic type’ behaviors, but not enough to qualify for an ASD diagnosis.

      The five (out of thousands) participants in AGRE who were found to have the microdeletion were also found to have a spontaneous mutation that was not found in the parent(s). The parents are unaffected thus this finding tends to relegate the entire concept of autism as 90% heritable and the broad autism phenotype as nothing more than meaningless psychobabble.

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    • olga farah

      I found this information most intriguing when I first read about it back in february 2008.
      I wanted to check at this site today if there were any new findings between the autism findings reported back on january 9th, 2008 at the UK and cancer of the brain.
      When I searched for chromosome 16 findings back then, I expected to see more info about autism…what I found instead was the connection of chromosome 16 to cancer. It made me rather sad…given that the day that this study about chr.16 and autism was published was the day that I buried my husband who died of brain cancer after a short 6 months awful ending to an exhuberant life…needless to say I have a daughter with autism and another son with a profound disability so neurological insults to inmune systems is a way of life in my home. Perhaps we need to do further studies to find out how many families with children with autism have primary family members with poor inmune systems and in many instances also who might be affected by cancer…..
      Olga S-Farah
      Post Fellowship Graduate – Family Support/2007 CHLA/USC.UCEED

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