Dr. Christopher Walsh of Boston Children’s Hospital, who is the senior author of one of the studies, says “It’s long been known that autism is a heritable condition and that some cases appear to run in families. Our studies are among the first to begin to address this heritable component”.
Autism research has consistently found that the disorders are incredibly complex. Two new studies in the Cell Press journal Neuron focus on identifying inherited genetic mutations linked with autism spectrum disorders. The mutations – which are different from the unstructured mutations that have been the focal point of prior studies – may offer important insights into the causes of autism.
The two groups sequenced the section of the genome that codes for proteins, also known as the exome, in people with autism, their relatives, and controls. One study referenced uncommon mutations that totally eliminate the role of specific genes – and consequently the appearance of a protein. Senior author Dr. Mark Daly of Massachusetts General Hospital and the Broad Institute says that “We utilized new genome-sequencing technologies to discover a component of autism that can be traced to recessive inheritance – that is, when a child inherits two broken copies of the same gene, one from each parent who is a carrier. He added that, there were twice as many autism cases as control individuals that were apparently missing an important protein somewhere in the genome. These conclusions indicate that 5% of autism risk is related to hereditary mutations that completely disturb the functions of genes.
Both Dr. Walsh and his colleague, Dr. Daly and his team acknowledged and characterized cases of autism due to the inheritance of two gene mutations, one from each parent. The researchers established that the partial loss of a gene’s function is linked to autism spectrum disorders. Several genes were identified – like those involved in neurometabolic pathways – that had never been linked with autism risk, and they showed a remarkable variability of severe autism in spite of inheritance of comparable genetic mutations.
Dr. Timothy Yu, the first author, of Boston Children’s Hospital, says, “these two studies firmly establish that recessive mutations contribute importantly to autism, not just in specialized populations but in the population at large.
This clearly establishes that with additional studies in the identification of the different genes that are mute or partly disabled in autism cases can present key clues toward discerning the underlying biology of autism spectrum disorders and potentially assist in generating further therapies.