Autism spectrum disorders are a clinically heterogeneous group of disorders that share common features. Only an estimated 10 to 15 percent of autism cases are monogenic — caused by mutations in a single gene — but the molecular alterations in these disorders could reveal common pathogenic mechanisms shared across the spectrum.

Functional brain imaging studies of individuals with autism suggest that brain activity in response to sensory stimuli is delayed, multisensory brain responses are integrated over a longer time frame, and activity across brain regions is less synchronous than in typically developing people.

About 15 to 30 percent of children with autism are at risk of epilepsy, which is roughly ten times higher than the general population. Additionally, a significant proportion of individuals with autism who don’t have clinically evident seizures show abnormalities in electroencephalography — a measure of electrical activity in the brain. Some genes implicated in epilepsy, such as the contactin gene family, are also risk factors for autism. And finally, preliminary data suggest that anticonvulsant drugs may be useful for treating some autism spectrum features.

Betty Diamond and her colleagues at The Feinstein Institute for Medical Research in Long Island, New York, demonstrated the presence of antibodies that bind to brain tissue in the blood serum of approximately 10 percent of mothers of a child with autism spectrum disorder. More than half of these women also have anti-nuclear antibodies. Autoimmune disease is also more prevalent in these women than in the general population.

Mutations in certain genes that encode proteins at the synapse, the junctions between neurons, are known to be associated with autism spectrum disorders. Two such families of proteins, neurexins and neuroligins, are thought to be important for assembling synapses. However, the role of these molecules in synapse formation and overall neuronal function is still poorly understood.

There is currently no cure for any autism spectrum disorder, and the current pharmacological treatments have had limited success. Finding treatments for autism has proven challenging for two major reasons. First, defects in multiple genes increase risk for autism, which makes it difficult to study and identify effective treatments. Second, drug screening in neurons, which are non-dividing cells, poses immense technical challenges. Benjamin Philpot and his colleagues at the University of North Carolina have sought to overcome these challenges by developing a novel neuronal drug screen to identify small-molecule compounds for treating autism caused by dysregulation of a single gene, UBE3A.

The most common inherited form of autism is fragile X syndrome, which is caused by genetic inactivation of the fragile X mental retardation protein (FMRP). In addition to intellectual disability, children with this disorder exhibit extreme social anxiety, poor eye contact, repetitive behaviors, hand flapping and tactile avoidance — hallmark characteristics of people with autism.

At least 100 different genes have been implicated in autism spectrum disorders. Although certain genetic variations do correlate with autism, other factors must be involved, as not all individuals with these genetic variations develop an autism spectrum disorder.

For individuals with autism, the process of socialization is derailed at a very early age. Typically developing babies are drawn more toward socially relevant aspects of their environment (e.g. people, particularly their eyes) than toward inanimate objects. Ami Klin and Warren Jones at Yale University have found that this is not the case for children with autism, who often possess a great deal of knowledge about their world, but are profoundly lacking in socialization.

Christopher Walsh and his colleagues at Boston Children’s Hospital have been studying the genetics of autism by analyzing inherited recessive mutations in consanguineous families — those in which the parents are related to each other (e.g., as cousins).