Researchers at Boston University on Thursday announced a breakthrough discovery about a gene associated with the risk of Alzheimer’s disease.This risk is tied to the APOE4 gene, which destroys brain cells if a person carries the gene. It puts them at higher risk for developing the disease, although inheriting the gene doesn’t necessarily mean one will develop the disease, according to the NIH. The APOE3 gene is the most common and isn’t known to affect Alzheimer’s risk.Although the link between the gene and the disease is well established, the mechanism responsible for the underlying risk in brain cells has been unclear in research until the recent discovery, according to researchers from the BU School of Medicine.Alzheimer’s is a progressive neurodegenerative disorder and is the most common cause of dementia. It affects more than 5.8 million individuals in the United States. In the recent finding, two important aspects of the gene were discovered — the human genetic background associated with the gene is unique to APOE 4 patients and the genetic defects are unique to human cells. “Our study demonstrated what the APOE4 gene does and which brain cells get affected the most in humans by comparing human and mouse models. These are important findings as we can find therapeutics if we understand how and where this risk gene is destroying our brain,” said assistant professor in the BU School of Medicine Julia TCW. Researchers used three models to investigate the effects of the gene on brain cells, human-induced pluripotent stem cells, post-mortem human brains and experimental models. It is also known that the gene carries a risk for Parkinson’s disease and rare genetic diseases.