News / Health

Study Finds Gene That May Raise Alzheimer's Risk in US Blacks

Reuters
— The largest study to date looking for genetic causes of Alzheimer's in African Americans may offer new clues about why blacks in the United States are twice as likely as whites to develop the deadly, brain-wasting disease.
       
The findings, published in the Journal of the American Medical Association on Tuesday, show that mutations in two genes that play a role in whites also contribute to Alzheimer's risk in blacks. One of those, known as ABCA7, may double the risk in blacks who have the mutation versus those who don't.
       
Although many genes have been found to raise the risk of Alzheimer's, most studies have been conducted in largely white populations, and few studies have looked specifically at genes that drive Alzheimer's in blacks. Part of that is because very few African Americans take part in gene studies looking at Alzheimer's risk.
       
The latest findings will need to be confirmed by other research teams, and critics say the study is incomplete until that work is done.
       
To get enough participants for the newly published study, researchers combined genetic information from 18 different Alzheimer's Disease Centers funded by the U.S. National Institutes of Health. They gathered information on 6,000 African Americans, 2,000 of whom had late-onset Alzheimer's disease, the most common form that occurs in older people.
       
The team then looked for genes that were most strongly associated with Alzheimer's. The strongest link was with a variant of a gene called apolipoprotein E or APOE, a gene that contains instructions for making a protein that carries cholesterol and is well-known risk factor for Alzheimer's.
       
The team found that a variant of this gene called APOE-e4 doubled the risk of Alzheimer's in blacks, in much the same way it does in whites.
       
But the study also turned up another gene that has only been weakly associated with Alzheimer's in whites. This gene, called ABCA7, which also plays a role in the production of cholesterol and fats, appears to have a much stronger effect in blacks.
       
"In whites, it increases risk by 10 to 20 percent, but in African Americans, it increases risk by about 70 to 80 percent.  It has a way larger effect size in African Americans,'' said Dr. Christiane Reitz of Columbia University Medical Center, who conducted the genetic analyses on the study.
       
ABCA7 is also involved in cholesterol metabolism, as are several of the genes which have been found in the past five years or so to be linked with Alzheimer's in whites.
       
"That seems to be a pathway that is involved in Alzheimer's disease,'' Reitz said.
       
Reitz said a variant form of APOE called APOE-e4 has the biggest effect, increasing the risk of Alzheimer's by about 200 percent. ABCA7 raised the risk by about 80 percent, and most other genes discovered so far increase risk by 10 to 20 percent.
       
Like other risk genes for the age-related form of Alzheimer's, the gene explains only part of the risk and likely will not lead to any new treatments soon. Reitz said it is clear that hundreds of genes are at work in Alzheimer's disease.
       
"ABCA7 and APOE are not the only genes involved in Alzheimer's disease in African Americans,'' Reitz said, adding that it would take tens of thousands of participants to detect some of the other risk genes. "What the study did show us is at least one gene which seems to have a major effect, and that's important to know.''
       
Representative Enough?
       
The next step is to study how the ABCA7 gene works in the brain, and the team still needs to validate the results of this study in another independent population of blacks, something that may be challenging.
       
According to Neil Buckholtz, director of the division of neuroscience at the National Institute on Aging, the study represented all of the well characterized genetic samples of blacks in the United States.

Dr. Allan Levey, director of Emory University's Alzheimer's Disease Research Center, said the study was significant for being the first large-scale genetic study done in African Americans. But he said a major limitation is that the study was not replicated in another population of blacks to confirm the findings, which is considered necessary to ensure its validity.
       
"Had this same study been done in whites, it would never have been published here,'' said Levey, referring to JAMA, a highly-regarded medical journal.
       
Troy Duster, a sociologist at the University of California, Berkeley and author of "Backdoor to Eugenics'' and contributor to "Whitewashing Race: The Myth of a Color-Blind Society,'' says the findings are too preliminary and the effect sizes too small to draw any definitive conclusions about differences in the risk of Alzheimer's between blacks and whites.
       
Without a replicating study in other groups who identify as African-American and as white, "it is impossible to interpret whether this small difference has significant meaning, or points to different etiologies (or the need for different treatments) in different groups,'' he said.
       
Heather Snyder, director of medical and scientific operations at the Alzheimer's Association, which funded two of the study authors, said the findings should spur new research into the potential reasons for this link between ABCA7 and Alzheimer's in African Americans.
       
"Really, that all requires more funding for Alzheimer's disease research,'' Snyder said.

You May Like

Mali's Female Basketball Players Rebound After Islamist Occupation

Islamist extremists ruled northern Mali for most of 2012, imposing strict Sharia law, and now some 18 months later, the region is slowly getting back on its feet More

Video Vietnamese Staging Chinese Product Boycott After Oil Rig Spat

Many Chinese-made products go unsold, for now, with numerous Vietnamese consumers still angry over recent dispute More

Koreas Mark 61st Anniversary of War Armistice

Muted observances on both sides of heavily-armed Demilitarized Zone that separates two decades-long enemies More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Students in Business for Themselvesi
X
Mike O'Sullivan
July 26, 2014 11:04 AM
They're only high school students, but they are making accessories for shoes, fabricating backpacks and doing product photography - all through their own businesses. It's the result of a partnership between a non-profit organization that teaches entrepreneurship and their schools. VOA's Mike O'Sullivan and Deyane Moses met the budding entrepreneurs near Los Angeles.
Video

Video Students in Business for Themselves

They're only high school students, but they are making accessories for shoes, fabricating backpacks and doing product photography - all through their own businesses. It's the result of a partnership between a non-profit organization that teaches entrepreneurship and their schools. VOA's Mike O'Sullivan and Deyane Moses met the budding entrepreneurs near Los Angeles.
Video

Video Astronauts Train in Underwater Lab

In the world’s only underwater laboratory, four U.S. astronauts train for a planned visit to an asteroid. The lab - called Aquarius- is located five kilometers off Key Largo, in southern Florida. Living in close quarters and making excursions only into the surrounding ocean, they try to simulate the daily routine of a crew that will someday travel to collect samples of a rock orbiting far away from earth. VOA’s George Putic has more.
Video

Video Not Even Monks Spared From Thailand’s Junta-Backed Morality Push

With Thailand’s military government firmly in control after May’s bloodless coup, authorities are carrying out plans they say are aimed at restoring discipline, morality and patriotism to all Thais. The measures include a crackdown on illegal gambling, education reforms to promote students’ moral development, and a new 24-hour phone hotline for citizens to report misbehaving monks. Steve Sandford reports from Bangkok.
Video

Video Virtual Program Teaches Farming Skills

In a fast-changing world beset by unpredictable climate conditions, farmers cannot afford to ignore new technology. Researchers in Australia are developing an online virtual world program to share information about climate change and more sustainable farming techniques for sugar cane growers. As VOA's Zlatica Hoke reports, the idea is to create a wider support network for farmers.
Video

Video Airline Expert: Missile will Show Signature on Debris

The debris field from Malaysia Airlines Flight 17 is spread over a 21-kilometer radius in eastern Ukraine. It is expected to take investigators months to sort through the airplane pieces to learn about the missile that brought down the jetliner and who fired it. VOAs Carolyn Presutti explains how this work will be done.
Video

Video Treatment for Childhood Epilepsy Heats up Medical Marijuana Debate

In the United States, marijuana is classed as an illegal drug by the federal government. But nearly half the states have legalized it, to some degree. Proponents say some strains of marijuana might have exceptional health benefits, for treating pain or inflammation in chronic conditions such as cancer, multiple sclerosis and epilepsy. Shelley Schlender reports on a strain of medical marijuana developed in Colorado that is reputed to reduce seizures in childhood epilepsy
Video

Video Airbus Adds Metal 3D Printed Parts to New Jets

By the end of this year, European aircraft manufacturing consortium Airbus plans to deliver the first of its new, extra-wide-body passenger jets, the A350-XWB. Among other technological innovations, the new plane will also incorporate metal parts made in a 3-D printer. VOA's George Putic has more.
Video

Video AIDS Conference Welcomes Exciting Developments in HIV Treatment, Prevention

Significant strides have been made in recent years toward the treatment and prevention of HIV, the virus that causes AIDS. This year, at the International AIDS Conference, the AIDS community welcomed progress on a new pill that may prevent transmission of the deadly virus. VOA’s Anita Powell reports from Melbourne, Australia.
Video

Video IAEA: Iran Turns its Enriched Uranium Into Less Harmful Form

Iran has converted its stockpiles of enriched uranium into a less dangerous form that is more difficult to use for nuclear weapons, according to the United Nations’ Atomic Energy Agency. The move complies with an interim deal reached with Western powers on Iran's nuclear program last year, in exchange for easing of sanctions. Henry Ridgwell reports for VOA from London.

AppleAndroid