DNA that scientists have long thought was linked to memory loss and cognitive limits in Alzheimer’s disease may not effect either, according to a finding involving a man who is missing the gene.
The individual studied showed no neurological signs of Alzheimer’s even though he lacked a protein normally produced by healthy forms of the APOE gene, according to a report in the journal JAMA Neurology. The protein, scientifically refered to as apolipoprotein E, helps carry cholesterol in the body.
The finding may mean scientists can disable a mutated form of the DNA that’s been associated with the protein clumps in the brain found in Alzheimer’s without harming a person’s ability to think, said Mary Malloy, a study author.
Minimizing the variant gene, dubbed APOE4, “may provide us with a new venue for intervention with Alzheimer’s disease, and other cognitive disorders,” said Malloy, professor of medicine and pediatrics at the University of California at San Francisco, in a telephone interview.
More than 5 million Americans now have Alzheimer’s disease, the most common form of dementia, and an estimated 35.6 million may struggle with it worldwide, according to the Geneva-based World Health Organization, and the number is expected to triple by 2050, according to the U.S.-based Alzheimer’s Association.
In the study, a 40-year-old California man was seen at UCSF for severe high cholesterol that wasn’t responsive to treatment. Researchers found he had no APOE in his body, a rare occurrence, yet he had normal cognitive and eye function, according to Malloy.
“We know from other diseases that there are many metabolic process that are very highly redundant that can come in and do a job if one is missing,” she said. “APOE has a purpose but maybe there are ways to get around that. Maybe another protein can take over.”
Joachim Herz, who wrote an accompanying editorial, said now that it’s been shown that a lack of APOE isn’t harmful to the brain, researchers can begin looking for ways to shut off the gene just within the brain.
“This opens the door to explore such possibilities more rigorously because we have the proof of concept that reducing APOE isn’t harmful to patients,” Herz, a professor of molecular genetics, neurology and neurotherapeutics at the University of Texas Southwestern Medical Center in Dallas, said in an interview.
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