STUDY In the largest genetic sequencing study of autism spectrum disorder (ASD) to date, researchers have identified 102 genes associated with risk for autism. The discovery shows significant progress towards teasing apart the genes associated with autism from those associated with intellectual disability and developmental delay, conditions which often overlap. According to the World Health Organisation (WHO), one in 160 children has an autism spectrum disorder (ASD). ASDs begin in childhood and tend to persist into adolescence and adulthood. In most cases the conditions are apparent during the first five years of life. "This is a landmark study, both for its size and for the large international collaborative effort it required. "With these identified genes we can begin to understand what brain changes underlie ASD and begin to consider novel treatment approaches," said Joseph D Buxbaum, Director of the Seaver Autism Center for Research and Treatment at Icahn School of Medicine at Mount Sinai. For the study published in the journal Cell, an international team of researchers from more than 50 sites collected and analyzed more than 35,000 participant samples, including nearly 12,000 with ASD, the largest autism sequencing cohort to date. Using an enhanced analytic framework to integrate both rare, inherited genetic mutations and those occurring spontaneously when the egg or sperm are formed, researchers identified the 102 genes associated with ASD risk. Of those genes, 49 were also associated with other developmental delays. The larger sample size of this study enabled the research team to increase the number of genes associated with ASD from 65 in 2015 to 102 today. In addition to identifying subsets of the 102 ASD-associated genes, the researchers showed that ASD genes impact brain development or function and that both types of disruptions can result in autism. "Through our genetic analyses, we discovered that it's not just one major class of cells implicated in autism, but rather that many disruptions in brain development and in neuronal function can lead to autism," said Buxbaum. It's critically important that families of children with and without autism participate in genetic studies because genetic discoveries are the primary means to understanding the molecular, cellular, and systems-level underpinnings of autism. "We now have specific, powerful tools that help us understand those underpinnings, and new drugs will be developed based on our newfound understanding of the molecular bases of autism," the researchers noted.