Alzheimer’s researchers study genes in Puerto Rican and Latino families

MIAMI – With Latinos being 1.5 times more likely than whites to develop Alzheimer’s, researchers are uncovering more insights into how genetics play a role in who is most at risk of developing the disease.

University of Miami researchers collaborated with doctors in Puerto Rico, Peru and Africa, looking for new genetic factors that contribute to risk factor and protection against Alzheimer’s, with the aim of finding new drug targets.

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

There are an estimated 6 million people in the United States with Alzheimer’s and its prevalence is projected to rise to nearly 14 million by 2050. It is the most common form of dementia in the elderly and slowly destroys memory and thinking skills . There is no cure and available treatments have limited effectiveness.

One group the researchers are looking at is the Puerto Rican population, who make up the second-largest Hispanic group in the continental United States. While, in the United States, 10.7 percent of the population age 65 and older have Alzheimer’s, in Puerto Rico the number is 12.5 percent. In the United States, it is the fifth leading cause of death in those over 65, but in Puerto Rico it ranks fourth in the same age group.

More than thirty years ago, when Alzheimer’s genetics research pioneer Margaret Pericak-Vance was at Duke University, she began looking to get more different populations involved in research.

Dr. Margaret Pericak-Vance.

Dr. Margaret Pericak-Vance.

At the time, most genetic studies of Alzheimer’s were being conducted in 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 then, we thought this must be important.”

He is now leading the Hussman Institute as it builds an extensive genetic database to research aspects of Alzheimer’s and genetic variation among Hispanic and African-descent communities.

Their research is helping to fill an important gap in minority research and could play a significant role in the development of Alzheimer’s drugs.

“A genetic target, in which pharmaceutical companies are showing interest, is twice as likely to have therapeutic success as non-genetic targets,” said Pericak-Vance.

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

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

“When we started looking at different groups, we saw that the risk was different,” Pericak-Vance said of findings published in 2018 based on a study of the genomes and APOE of different groups. “For example, among individuals of African descent or with African ancestry, the risk was lower.”

“This paper that we published allowed people to see that ancestry mattered and that we needed to include different populations in the research,” he said.

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

“Coming from an underdeveloped country, I have faced and understood the need for inclusion and representation of different populations in genetic research,” said Celis, originally from Venezuela. “My main focus has been on increasing participation in genetic research from diverse populations, especially Latino Hispanic communities.”

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

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

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

Celis and Feliciano-Astacio and the Hussman Institute team are studying large families in Puerto Rico and what they call “multiple families,” meaning they have more than two or three people who have 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 lonely,” she said, adding that it affected all socioeconomic backgrounds.

Celis is also focused on a second project studying chromosome 14, which harbors a well-known gene they see in early-onset Alzheimer’s. She said she is trying to identify the molecular mechanisms driving this particular case and the broad range of ages of onset they see in individuals carrying this particular genetic variant.

A variant found only among Hispanic Caribbeans

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 the 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 the John P. Hussman Institute for Human Genomics)

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

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

“We identified that the particular region harboring this variant associated with Alzheimer’s disease risk is against the African ancestral background,” Celis said. “However, that particular variant has only been found in Hispanic Caribbean individuals, primarily of Puerto Rican ancestry, which is known in the genetics world as a founder mutation, meaning that something happened in the island after colonization that created this type of variant. within 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 essential to driving precision medicine across diverse populations,” said Pericak-Vance.

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