(RxWiki News) Brain overgrowth and an abnormal, excess number of neurons could be associated with the development of autism. Boys with autism spectrum disorder (ASD) have a 67 percent excess of cortical cells, which are developed in the womb before birth.
Because boys are three to four times more likely to have autism than girls, researchers have suspected that the disorder's genes may be linked to the X chromosome.
"New genetic keys may unlock the mystery of autism."
New research has found a variation in a gene called TBL1X (transducin ß-like 1X-linked), which is linked to an increased risk of autism in boys. TBL1X is part of the complex mechanism that controls embryonic neurological development and the maintenance of brain function in adults.
A team of researchers across the U.S. combined three sets of genetic data from more than 3000 affected children and their family members, as well as non-related control individuals. The study compared single nucleotide polymorphisms (SNP, a small variation between different pieces of DNA) on the X chromosomes of the children with ASD to the control groups, and found differences within the genes for Duchenne muscular dystrophy (DMD), IL1RAPL2 (involved in inflammation), and in TBL1X.
Autism affects about one in 100 children and creates a range of problems in language, communication and understanding other people's emotional cues, all of which can lead to difficulties in social situations.
Eden Martin of the Hussman Institute for Human Genomics, who lead the research team explained, "The SNP in TBL1X is associated with an increase in risk for ASD of about 15 percent. This could reflect either an unidentified rare mutation (or mutations), which has large impact, or a more common change with a more subtle effect, on the development of ASD. Further study of TBL1X will help us to pinpoint the DNA changes involved and help us to understand exactly how these changes and the Wnt-signaling pathway is involved in ASD."
The findings were published in BioMed Central's open access journal Molecular Autism, and will be published November 9, 2011 by the Journal of the American Medical Society.