Humans have an extra Y chromosome, says study; Here's why it's bad news for men

New research finds that men with an extra Y chromosome may face a higher risk of autism — offering fresh insight into how sex chromosomes shape brain health.

A new study has uncovered an unexpected link between autism and Y chromosomes, bringing fresh insight into how sex chromosomes affect brain health, especially in men. It shows that men who have an additional Y chromosome might face a higher chance of developing neurodevelopmental disorders.

What the Study Found

In a sample of over 177,000 people, scientists found that participants with XYY or XXY chromosomal variations had twice the likelihood of receiving an autism diagnosis compared to those with typical XY or XX karyotypes.

The research showed that the extra Y chromosome (XYY) seemed to have a stronger connection to risk than an extra X (e.g. XXY).

The results challenge long-standing assumptions about sex chromosome influence by highlighting the role of the Y chromosome as a potential risk factor in autism, unlike earlier studies that focus on X-protective effects.

Also Read: Is autism a disease? Can it be cured? Bursting myths related to the neurodevelopmental disorder

The research brings a new angle to our grasp of how biological sex relates to brain growth:

• It backs the idea that genes contributing to autism may work not just through the "protective" X chromosome but also through different vulnerabilities tied to Y-chromosome content.
• It points out that "quiet" chromosome changes in healthy men might affect brain circuits, thinking traits, or growth outcomes.
• It stresses the need to look at more than just genes alone—sex chromosomes, epigenetics, surroundings, and how they all interact matter.

The study shows a link, not a cause. Having an extra Y doesn't mean you'll have autism or any disorder.

The group of people with XYY or XXY is quite small (350 in this data set), so we should be careful when drawing conclusions.

Additional research is needed to explore how an extra Y might mechanistically influence brain development—and whether its effects vary across populations.

What This Means for You

Men with undiagnosed chromosomal variations may one day benefit from screening in neurodevelopmental or psychiatric contexts—though such testing isn’t standard now.

Also Read: What is AuDHD? Psychiatrist reveals how Autism and ADHD together change daily life

Families or clinicians working with autism should consider the full genetic picture, including sex chromosome anomalies, when evaluating risk or treatment plans.

As the research continues,  it’s a reminder that genetics is complex and often hidden, and the framework of “normal vs. variant” is more fluid than we assume.

FAQs on Extra Y Chromosome and Autism

Q: What is an extra Y chromosome?

A: An extra Y chromosome, also known as XYY syndrome, is a genetic condition where a male has an additional Y chromosome, making their karyotype 47,XYY instead of the typical 46,XY.

Q: How does an extra Y chromosome affect autism risk?

A: Studies have shown that males with an extra Y chromosome have a higher likelihood of receiving an autism diagnosis compared to those with typical XY karyotypes.

Q: Does having an extra Y chromosome mean a person will definitely have autism?

A: No, having an extra Y chromosome increases the risk but does not guarantee that a person will develop autism or any neurodevelopmental disorder. Further research is needed to understand the exact mechanisms involved.

Q: Should men with an extra Y chromosome get screened for autism?

A: While current practices do not include standard screening for chromosomal variations like XYY syndrome, future advancements may make such screenings beneficial in neurodevelopmental or psychiatric contexts.

Disclaimer: This article, including health and fitness advice, only provides generic information. Don’t treat it as a substitute for qualified medical opinion. Always consult a specialist for specific health diagnosis.