'Common' rare genetic factors responsible for developing autism: Study

A recent study has proved that 60 percent of the risk for developing autism is caused by genetics and a major portion of that risk is caused by inherited variant genes that are common in the population and present in individuals without the disorder.

The study, led by Joseph D. Buxbaum, Director of the Seaver Autism Center for Research and Treatment and Professor of Psychiatry, Neuroscience and Genetics and Genomic Sciences at the Icahn School of Medicine at Mount Sinai and other researchers, has revealed that though autism is thought to be caused by an interplay of genetic and other factors, there has been no consensus on their relative contributions and the nature of its genetic architecture.

Buxbaum said that they have shown very clearly that inherited common variants comprise the bulk of the risk that sets up susceptibility to autism and while there are families that can be genetically loaded for autism risk, additional rare genetic factors are required to actually produce the disorder in a particular family member.

The current study found that about 52.4 percent of autism was traced to common and rare inherited variations, with spontaneous mutations contributing a modest 2.6 percent of the total risk.

Buxbaum added that people have been focusing on de novo mutations, such as the ones that can occur in the sperm of an older father, they have found that mutations are also key contributors, it is important to know that there is underlying risk in the family genetic architecture itself.

He further said that in a given family, a de novo mutation could be a critical determinant that leads to the manifestation of autism spectrum disorder in a particular family member and if the family had a common variation that puts it at risk, an added de novo mutation could push an individual over the edge and result in that person developing the disorder.

The study is published in July 2014 edition of Nature Genetics.