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Genetic variant helps stave off early-onset Alzheimer’s, could hold key to developing drugs

Building on a 2019 discovery, researchers discovered 27 people from one Colombian extended family whose rare genetic variant seems to have helped them stave off the effects of Alzheimer's.

(CN) — Millions of people around the world live with Alzheimer's disease. Scientists don’t exactly know why people get it, but a study published Wednesday suggests that a rare genetic variation not only can offer protection against early-onset Alzheimer’s, but also may hold the key for developing drugs to combat the disease.

A team of researchers in the U.S. and Colombia studied more than 1,000 people in the Antioquia region of Colombia, all descendants of a family with a genetic predisposition to develop Alzheimer’s in their 40s.

The family are the world’s largest known carriers of the “Paisa” mutation: 1,200 members of the 6,000-member extended family have the genetic variant linked to the accelerated development of Alzheimer's. Because of this, family members with the mutation start having cognitive impairment issues in their 40s, which leads to dementia in their 50s, and death from complications of dementia in their 60s.  

In 2019, researchers found one member of the family who had the mutation — but didn't develop cognitive impairment issues until her late 70s. She had two copies of a rare gene variant called the “Christchurch” variant, named after the city in New Zealand where it was originally found.  

The discovery paved the way for Wednesday's study, published in the New England Journal of Medicine.

With the help of brain imaging scans, neuropsychological assessments and hundreds of clinical records from 1995 to 2022, researchers found that out of 1,077 people in the family, 27 carried both the Paisa mutation and only one copy of the Christchurch variant. On average, they began showing signs of cognitive decline around age 52 — five years later than family members who didn’t carry the variant. They also showed signs of dementia four years later than their kin without the variant.

The researchers' findings indicate that developing drugs that target that genetic pathway could be a successful way to tackle Alzheimer’s.  

“It’s tantalizing to think about the prospect of such a drug,” said Joseph Arboleda-Velasquez, a lead study author and an associate professor at the Boston specialty hospital Mass Eye and Ear.

In the paper, the researchers explain that the study was limited to a relatively small group of people who have both the Paisa and Christchurch genetic variants — and the cohort, members of an extended family who live in the same region, was rather homogeneous. Further studies involving larger, more diverse, groups of people are necessary to see if the findings can be replicated.   

“As a next step, we are currently focused on improving our understanding of the brain resilience among the remaining family members who carry one copy of the Christchurch variant," said Yakeel T. Quiroz, co-lead author and the director of the Familial Dementia Neuroimaging Lab at Massachusetts General Hospital, in a press release. 

That means conducting structural and functional MRI scans and cognitive evaluations, Quiroz said, in addition to analyzing blood samples to assess family members' "protein and biomarker profiles."

In the meantime, Arboleda-Velasquez explained, the new study marks progress since the 2019 discovery. By locating more people with similar genetic mutations who staved off Alzheimer’s, researchers were able to offer a critical mass of data that supports the correlation.

“The potential for helping people is tremendous,” he said. 

Categories / Health, Science

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