A higher risk of autism appears to be linked to the Y chromosome, a Geisinger study found, offering a new explanation for the higher prevalence of autism in men. The results were published today in Nature Communications.
Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by impaired social interaction and communication, and restricted, repetitive patterns of behavior, interests, and activities. ASD is almost four times more common among men than women, but the reason for this disparity is not well understood.
A common hypothesis involves the difference in sex chromosomes between men and women: typical women have two X chromosomes, while typical men have one X chromosome and one Y chromosome.
“A leading theory in this field is that protective factors on the
The Geisinger research team, led by Dr. Oetjens and Alexander Berry, Ph.D., a staff scientist, sought to determine the effects of the X and Y chromosomes on autism risk by examining ASD diagnoses in people with a number abnormal X or Y chromosomes, a genetic condition known as sex chromosome aneuploidy.
The team analyzed ASD and genetic diagnosis data on 177,416 patients enrolled in the SPARK study from the Simons Powering Autism Foundation and Geisinger’s MyCode Community Health Initiative. They found that individuals with an extra X chromosome had no change in ASD risk, but that those with an extra Y chromosome were twice as likely to have an ASD diagnosis. This suggests a risk factor associated with the Y chromosome rather than a protective factor associated with the X chromosome.
“While they may seem like two sides of the same coin, our results encourage us to look for autism risk factors on the Y chromosome rather than limiting our search to protective factors on the X chromosome,” Dr. Berry said. “However, more research is needed to identify the specific risk factor associated with the Y chromosome.”
This analysis also confirms previous work by showing that the loss of an X or Y chromosome, known as Turner syndrome, is associated with a large increase in the risk of ASD. More research is needed to determine whether ASD risk factors associated with sex chromosome aneuploidy explain the sex difference in ASD prevalence.