WEDNESDAY, Jan. 7 (HealthDay News) -- Researchers have identified nine genes that might make people more likely to develop Alzheimer's disease.

In addition, they confirmed earlier reports that a variation in the vitamin D3 receptor gene, on chromosome 12, might also increase risk for Alzheimer's. Low levels of vitamin D have been found in people with Alzheimer's and other dementias, leading researchers to suspect a link.

"The vitamin D3 receptor finding on chromosome 12 is really exciting, because it implicates a potential biological pathway that has been of interest in neurological disorders," researcher Jonathan L. Haines, of Vanderbilt University Medical Center, said in a news release from the University of Miami Miller School of Medicine. Researchers from the university's Miami Institute for Human Genomics collaborated on the study with colleagues from Vanderbilt's Center for Human Genetics Research.

In their study, the researchers compared 550,000 genetic variations in about 500 people with Alzheimer's and 500 people without the disease

Their findings, published in the January issue of The American Journal of Human Genetics, "open the door for increased understanding of this important neurological disorder," researcher Margaret A. Pericak-Vance, of the Miami institute, said in the news release.

"We now have exciting new directions to explore," she said.

The identification of new Alzheimer's genes could lead to a better understanding of the causes of Alzheimer's, the most common type of dementia among older people. Currently, doctors and scientists remain uncertain about what starts the irreversible and progressive brain disease.

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