Female chromosomes offer protection against Alzheimer's

Women with this disease live longer than men.

Women with Alzheimer's live longer than men with the disease, and scientists at the University of California, San Francisco (United States) now have research evidence in humans and mice that this is because they have genetic protection against the ravages of the disease, as published in the journal 'Science Translational Medicine'.

By having a second X chromosome, women get two "doses" of a protective protein from a gene that only exists on this female sex chromosome. Some people, both men and women, have an especially strong variant of this gene, called KDM6A, which gives them even more protection. But, because of the way sex chromosomes work (women have two Xs, but men only have one), women have two copies of this gene that produce the protective protein.

The new study offers the first look at how sex chromosomes affect vulnerability to Alzheimer's. And it helps explain why women survive longer and with less severe symptoms than men during the early stages of the disease, even when they have comparable levels of toxic Alzheimer's proteins in their brains.

"Challenge a dogma"
"This finding challenges a long-standing dogma that women are more vulnerable to Alzheimer's," said Dr. Dena Dubal, associate professor of neurology at UCSF, lead author of the study and member of the UCSF Weill Institute for Neurosciences. More women than men have Alzheimer's because they survive to older ages, when the risk is greatest. But they also survive with the disease for longer."

While much of a woman's second of the proteins encoded by those genes.

The researchers focused on one of these active genes, KDM6A, which is already known to be involved in learning and cognition: when this gene malfunctions, it causes Kabuki syndrome, characterized by developmental delay and intellectual disability. from mild to severe.