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New Cause For Autism Discovered
ScienceDave | July 24, 2007 at 06:51 amby
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For example, any mutation in a woman's egg cells (her germ line), accumulated will be passed on to 50% of her future children - 50% because each child shares half their DNA from each parent. A more familiar example of germ-line mutations, then, is the relationship between ionizing radiation and birth defects.
Although parent's of either sex are just as likely to accrue such a defect, males were 3 times more likely to experience severe symptom of autism. This suggests women were more likely to be carriers of this particular vector for autism. Why? Well, their sons inherit either one of their mother's X chromosomes, while inheriting their father's only Y chromosome. Since sons will only have one copy of the X chromosomal genes, they will be more likely to express the full symptoms of their inherited disease.
“The fact that germ-line mutations increase with age places older parents at a higher risk of having children with autism, explaining a pattern that has been recently observed,” said CSHL co-author of the study Michael Wigler, Ph.D.
Furthermore, the research group identified two groups or risk classes of parents with autistic children - a group carrying the germ-line mutation and one that does not. As mentioned, women with the mutation can pass it on to their chidlren without actually displaying symptoms due to the nature of the mutation itself.
The models suggest that about half of autistic children are born to parents with no previous genetic predisposition to autism, suggesting that the cases are caused by spontaneous mutations...
...The researchers' model suggested that about a quarter of autistic children have inherited a copy-number mutation from their parents.
"It's a new way of looking at the data," says Rapin.
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