Researchers studying autism prevalence should take into account the continuous nature of autism symptoms in the general population, says John Constantino.
A comparison of autism-like behaviors in nearly 10,000 pairs of fraternal twins suggests that girls are somehow protected from the disorder. The findings, published 19 February in the Proceedings of the National Academy of Sciences, may partly explain why autism is four times more common in boys than girls.
Children with attention difficulties may later show signs of autism, such as trouble holding a conversation, according to a study published 14 November in Psychological Medicine.
Full siblings are twice as likely as half siblings to share a diagnosis of autism, according to a short report published 28 February in Molecular Psychiatry. The results suggest that genetic factors play an important role in the risk of developing autism, the researchers say.
Twin brothers who have autism carry a non-inherited duplication that overlaps with 16p11.2, a chromosomal region that has been associated with autism. Their brother, who also has autism, has a nearby deletion within 16p11.2, according to a study published 11 January in the European Journal of Human Genetics.
Autism and attention deficit hyperactivity disorder show genetic and neurobiological overlap, which may provide clues to the origin of both disorders, says Joel Nigg.