Alzheimer’s researchers study genes of Puerto Rican and Latin American families

MIAMI — With Latinos 1.5 times more likely than whites to develop Alzheimer’s disease, researchers are uncovering more information about the role of genetics in who is most at risk of developing the disease.

Researchers from the University of Miami have teamed up with doctors from Puerto Rico, Peru and Africa to find new genetic factors that contribute to the risk factor and protection against Alzheimer’s disease, in the goal of finding new drug targets.

They found that in Puerto Rico people have a higher propensity for Alzheimer’s disease and part of the reason could be a genetic variant they discovered.

In the United States, approximately 6 million people have Alzheimer’s disease and its prevalence is expected to reach nearly 14 million by 2050. It is the most common form of dementia in older adults and it slowly destroys memory and thinking skills. There is no cure and available treatments have limited effectiveness.

One of the groups the researchers are looking at is the Puerto Rican population, which is the second largest Hispanic group in the continental United States. While in the United States, 10.7% of the population aged 65 and over has Alzheimer’s disease, in Puerto Rico the number is 12.5%. In the United States, it is the fifth leading cause of death among people over 65, but in Puerto Rico it ranks fourth in the same age group.

More than three decades ago, when the pioneer of Alzheimer’s genetic research, Margaret Pericak-Vance, was at Duke University, she began trying to involve more diverse populations in research.

Dr. Margaret Pericak-Vance.

At the time, most genetic studies of Alzheimer’s disease were conducted on non-Hispanic white populations of European ancestry, with Hispanic and African ancestry communities largely ignored.

“It just hasn’t been done,” said Pericak-Vance, director of the John P. Hussman Institute for Human Genomics at the University of Miami Miller School of Medicine. “But even back then, we thought it must have been important.”

Now she directs the Hussman Institute which is building a large genetic database to research aspects of Alzheimer’s disease and genetic variations among Hispanic and African-descended communities.

Their research helps fill a major gap in research on minorities and could play an important role in drug development for Alzheimer’s disease.

“A genetic target, which is of interest to pharmaceutical companies, is twice as likely to be therapeutically successful as non-genetic targets,” Pericak-Vance said.

The Hussman Institute is one of the top programs funded by the National Institute on Aging, which is part of the National Institutes of Health in the United States. Since July, they have received over $100 million for research in this area.

A variant of the APOE gene, APOE4, is considered the strongest genetic risk factor for late-onset Alzheimer’s disease, and most studies initially included only people of European ancestry.

“When we started looking at different groups, we found the risk was different,” Pericak-Vance said of the results they published in 2018 based on a study of genomes and APOE. of different groups. “For example, in people of African descent or African descent, the risk was lower.”

“This paper that we published made people see that ancestry matters and that we need to include diverse populations in research,” she said.

Dr. Katrina Celis, an associate scientist at the Hussman Institute who studies Alzheimer’s disease in Hispanic populations, has spent the past 13 years focusing on genetic research.

“Coming from an underdeveloped country, I faced and understood the need to include and represent diverse populations in genetic research,” said Celis, originally from Venezuela. “I have primarily focused on increasing the participation in genetic research of diverse populations, especially Latin American Hispanic communities.”

Dr. Katrina Celis.  (Courtesy of John P. Hussman Institute for Human Genomics)

Dr. Katrina Celis. (Courtesy of John P. Hussman Institute for Human Genomics)

Celis collaborates with Dr. Briseida Feliciano-Astacio, neurologist and principal investigator at the Universidad Central del Caribe, in Bayamón, Puerto Rico.

Celis and Feliciano-Astacio and the team at the Hussman Institute are studying large families in Puerto Rico and what they call “multiplex families”, meaning they have more than two or three people with the disease of Alzheimer’s.

Feliciano-Astacio said the island’s aging population is struggling because many young Puerto Ricans have left due to the economic situation.

“There are a lot of older people who are alone,” she said, adding that it has affected all socio-economic backgrounds.

Celis is also focusing on a second project studying chromosome 14, which houses a well-known gene they see in early Alzheimer’s disease. She said she was trying to identify the molecular mechanisms behind this particular case, and the wide range of age of onset they see in individuals carrying this particular genetic variant.

A variant found only among the Hispanic Caribbean

Dr. Katrina Celis, Director of Research Support Larry Adams, and Dr. Parker Bussies prepare to see Alzheimer's patients and their families in Puerto Rico for PRADI.  (Courtesy of John P. Hussman Institute for Human Genomics)

Dr. Katrina Celis, Director of Research Support Larry Adams, and Dr. Parker Bussies prepare to see Alzheimer’s patients and their families in Puerto Rico for PRADI. (Courtesy of John P. Hussman Institute for Human Genomics)

Puerto Ricans are a mixed population and their genetic ancestry is mostly made up of European, African, and Native American or Native American ancestry.

“We are the first group to have identified that this variant actually occurs in African ancestry,” Celis said of the variant on chromosome 14.

“We identified that the particular region that harbors this variant associated with Alzheimer’s disease risk is on the African ancestral background,” Celis said. “However, this particular variant has only been found in Hispanic individuals from the Caribbean, primarily of Puerto Rican descent, which is known in the genetic world as a founder mutation, meaning something happened on the island after colonization that created this type of variant in the genetic information of these individuals.

Celis and Pericak-Vance agree that including more diverse populations is the only way forward.

“Inclusion and awareness are key to advancing precision medicine in diverse populations,” Pericak-Vance said.

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