Genetic Trait May Delay Alzheimer’s Onset

Researchers have discovered a rare genetic trait that could delay the onset of Alzheimer's in people who face an overwhelming risk of developing the disease.

The research was isolated to South America where there are a 1,000 members of an extended family in Colombia who carry a genetic mutation that puts them at near certain risk of developing early-onset Alzheimer's disease. The symptoms usually begin when the relatives are in their mid-40s. The mutation carriers are part of an extended family of about 6,000 people who live in and around Medellin, Colombia. Using advances in genetic testing, doctors identified the inherited mutation that triggered early-onset Alzheimer's in these family members.

A study published Wednesday, June 26, 2024 in The New England Journal of Medicine reported that 27 people from the extended Colombian family who carried a genetic variant called Christchurch developed Alzheimer's disease several years later than expected. The findings build on early research in 2019 from a unique family predisposed to pass on the disease.

In 2019, researchers discovered a woman who carried the Paisa mutation and did not experience symptoms of Alzheimer's until she reached her 70s – about three decades later than the symptoms have typically appeared among Paisa mutation carriers. Genetic testing revealed this woman also had two copies of the Alzheimer's gene APOE3 variant, called the Christchurch variant.

In the study published this week, researchers examined whether Christchurch offered extra protection to people who also have the Paisa mutation. They found 27 people with the Paisa mutation and one copy of the Christchurch variant. Those individuals preserved normal memory and thinking longer than a comparable group who just had the Paisa mutation.

The group that only had Paisa showed signs of disease at a median age of 47, while people who carried Christchurch and Paisa did not exhibit memory and thinking problems until they were 52 - five years later.

Scientists from Mass General Brigham believe the evidence could be used to develop an Alzheimer's drug or medication that replicates the protective effects of the Christchurch genetic variant.

Eric Reiman, executive director at Banner Alzheimer’s Institute in Phoenix and a co-author of the study, said the study bolsters the "idea that this rare variant of the major genetic risk factor for Alzheimer's disease plays a protective role in the development of Alzheimer's."

Reiman said further research is needed into the underlying role of APOE on hallmarks of the disease, including beta-amyloid plaques and tau tangles found in Alzheimer's patients.

Source: USA Today