Researchers have long focused on estrogen and testosterone to explain why men and women experience different health outcomes. A comprehensive review published in Science now highlights that the X and Y chromosomes themselves play a direct role in how our cells age and fight disease.
Chromosomes as health drivers
Co‑lead author Dr. Dan Theodorescu explains that the sex chromosomes carry genetic instructions that shape cellular function throughout a person’s life. “X and Y chromosomes are often thought of as simple determinants for biological sex, but their role in human health is much larger,” he said.
The review synthesizes evidence from human studies, mouse models and advanced genomic technologies. It finds that the presence or loss of these chromosomes influences immunity, metabolism, brain health, cancer development and cardiometabolic disease, independent of circulating hormone levels.
How the X chromosome matters
Women have two X chromosomes, one of which is largely inactivated early in development. However, some genes escape inactivation and can reactivate with age, giving female cells extra copies of certain genetic instructions. In mouse experiments, the origin of the active X—whether it came from the mother or the father—affected brain aging and memory performance. Cells that relied mainly on the maternal X showed faster cognitive decline.
Loss of an X chromosome in women’s blood cells has been linked to a higher risk of leukemia, though the broader health implications remain under investigation.
The Y chromosome’s hidden influence
Men inherit a single X from their mother and a Y from their father. Research shows that loss of the Y chromosome in blood cells—a common age‑related change—correlates with increased rates of cancers, heart disease, severe infections and Alzheimer’s disease.
Dr. Theodorescu’s laboratory discovered that tumors lacking the Y chromosome can evade the immune system, yet they may respond more favorably to immunotherapy. This suggests that Y‑chromosome loss could serve both as a biomarker of disease risk and a potential therapeutic target.
Implications for personalized medicine
The authors argue that recognizing sex‑chromosome differences can improve how clinicians design trials and choose treatments. “When clinical trials are designed to be sex‑aware, researchers can turn these cellular differences into personalized medical care,” Theodorescu said.
Understanding the distinct genetic contributions of the X and Y chromosomes may lead to diagnostics that better predict disease risk and therapies that are tailored to each patient’s unique genetic profile.
Future directions
The review calls for more research into how chromosome loss interacts with other age‑related changes and how these insights can be translated into clinical practice. By expanding the focus beyond hormones, scientists hope to uncover new pathways for preventing and treating a wide range of conditions that affect both men and women.
Original reporting: KTBS 3 (Shreveport) — read the source article.
