Autism may occur more than once in a family. Until now, it was assumed that autistic siblings had the same underlying cause to their condition. Now, a new study has found that siblings with autism do not share the same genetic risk factors and are as different as other brothers and sisters usually are.
In the past, researchers into autism found hundreds of spots on the human genome where a mistake appears to raise the risk of autism or another condition on the autism spectrum. Previous studies looked at only small parts of the genome of an individual rather than the entirety of the individual's genes on all his or her chromosomes. Often, geneticists would look at this genetic profile in a first child with autism to try to predict whether the parents might have a second child with autism. This new finding means that such predictions are unlikely to be useful.
In this study, a research team analyzed the entire genomes of families with two children with autism spectrum disorder. In all the families, the genomes of both parents and the affected children were completely sequenced. They found that almost 70% of the siblings with autism had different genetic mutations that appear to be related to autism. Only about 30% of the siblings shared a genetic mutation that may be associated with autism. Siblings who have different mutations tended to show different symptoms of autism.
This is an important finding in the continuing search for the biological causes of autism. However, this research is also important because the data and its analysis have been published on line in a format that is available to anyone. More than 1,000 genomes of autistic individuals with the identifying information removed have been uploaded to a portal in Google Cloud Platform that is run by Autism Speaks, an autism advocacy organization.
The study was published in Nature Medicine and was funded by Autism Speaks.
