Washington, July 24 (ANI): A new study has found that almost half of all cases of male autism may be caused by spontaneous genetic accidents, rather than an inherited genetic predisposition that is passed down through generations.
Researchers, who studied the genetic patterns of the condition, also suggest that progeny who inherit such mutations are at a greater risk of having an autistic child themselves.
The authors of the study suggest that spontaneous mutations in the DNA of an afflicted child or their parent may play a much larger role than formerly thought in sporadic cases of autism.
The genetic origins of the neurological condition are still uncertain, but in a recent paper, US researchers reported that spontaneous mutations, or tiny glitches in the DNA, were common in about 10 per cent of the autistic patients they studied.
Michael Wigler, a geneticist at Cold Spring Harbor Laboratory in New York and his colleagues did a mathematical analysis of three databases on the incidence of autism to see if this new theory could explain the distribution of cases.
In 86 families with two autistic children and a third, male child, 42 of the third-born children showed autistic symptoms, the researchers report in Proceedings of the National Academies of Sciences2.
This suggests that parents had a one-in-two chance of passing on a mutation to their offspring, matching a dominant inheritance pattern. Using mathematical models, Wigler's team found that the simplest way to explain the patterns of autism inheritance was to divide parents into two risk classes: those who carry a pre-existing autism-causing mutation, and those who do not.
The models propose that about half of autistic children are born to parents with no previous genetic predisposition to autism, signifying that the cases are caused by spontaneous mutations.
"For the first time, we have a model that explains the sporadic and the inherited forms of autism," Nature.com quoted Wigler, as saying.
Given that spontaneous mutations in DNA increase with age, and that many women in industrialized nations are postponing childbirth until the last minute, the theory may also explain why older parents are at greater risk of having autistic children, Wigler said.