Researchers explore influence of Y chromosome on likelihood of autism spectrum disorder

An increased likelihood of autism appears to be linked to the Y chromosome, according to a study from the United States.

Alexander Berry and colleagues note, “A female protective effect has long been postulated as the primary explanation for the four-fold increase of ASD diagnoses in males versus females. However, genetic and epidemiological investigations of this hypothesis have so far failed to explain the large difference in ASD prevalence between the sexes.”

Berry comments, “[O]ur results encourage us to look for autism risk factors on the Y chromosome instead of limiting our search to protective factors on the X chromosome.”

To investigate this issue, the researchers analyzed data on more than 177,000 individuals. Specifically, they looked at the effects of aneuploidy, or an abnormal number of X or Y chromosomes within a cell, exploring the effects of an extra X chromosome, an extra Y chromosome, or haploinsufficiency (the lack of one X or Y chromosome).

The researchers found that an extra Y chromosome increased the odds of ASD significantly, while an extra X did not affect these odds. Among females, they add, there was a strong association between a missing X chromosome and the likelihood of autism, “confirming sex chromosome haploinsufficiency as a strong ASD risk factor.”

Berry comments, “[O]ur results encourage us to look for autism risk factors on the Y chromosome instead of limiting our search to protective factors on the X chromosome. However, further research is needed to identify the specific risk factor associated with the Y chromosome.”