New Gene for Alzheimer's Discovered

lily1984 submitted, created time 4 months 3 weeks (www.bloomberg.com)

Scientists have discovered a gene that raises the risk of late-onset Alzheimer's disease by as much as 77 percent and provides scientists with a second genetic target for developing new treatments for the disorder.

One copy of the gene, called calcium homeostasis modulator 1, or CALHM1, increases the likelihood of late-onset Alzheimer's by 44 percent, while two copies boost the risk 77 percent. About a quarter of the population has one copy, said study author Philippe Marambaud from the Albert Einstein College of Medicine in New York. The research was published in the journal Cell.

Only one other gene is implicated in late-onset Alzheimer's, called ApoE4, and it occurs in about 40 percent of patients who develop the disease after the age of 65, according to the National Institute on Aging. Alzheimer's disease will claim about one in eight baby boomers -- those born between 1946 and 1964 -- or about 10 million Americans, according to the Chicago-based Alzheimer's Association, an advocacy group.

"This is a very interesting drug target," said Marambaud, who also is an assistant investigator at the Feinstein Institute for Medical Research, a Manhasset, New York-based group that studies the underlying causes of diseases. ``This is an interesting avenue because we may save a lot of time in terms of screening for safety and efficacy."

The group said Medicare spending for Alzheimer's patients will jump to $38 billion in 2025, when the baby boomer generation starts to reach the median age for nursing home admission.

Hippocampus

The gene is active in a region of the brain affected early in Alzheimer's, the hippocampus. This part of the brain is important for creating and storing memories. Early symptoms of Alzheimer's disease include forgetfulness and decreased attention, according to the Mayo Clinic.

The CALHM1 gene controls certain calcium channels, which allow electrically charged calcium molecules to enter cells and spur production of proteins, called beta amyloids, that are associated with the disease. Drugs that target calcium channels already exist, though not the ones this gene controls, said J. Kevin Foskett, a co-author and professor of physiology at the University of Pennsylvania in Philadelphia.

Foskett was the senior researcher on a second study, published in the journal Neuron, which found that exaggerated calcium channel activity appeared to make excessive amounts of beta amyloid. Clumps of beta amyloid form the plaques that damage brain cells, eventually causing them to die.

Drug Targets

"This allows us to go after known drug targets, which is what these are, that may be causing problems upstream of amyloid," Foskett said in a telephone interview.

Other genes identified with Alzheimer's disease have been linked to early onset Alzheimer's, a rarer form that occurs in only 5 to 10 percent of Alzheimer's patients, according to the Mayo Clinic.

In March, other researchers discovered that adult children of two parents with Alzheimer's disease had twice the risk of getting the illness as the general population. That finding suggested that more genes were involved with the illness than previously thought, said Thomas Bird, a neurologist at the Seattle Veterans Affairs research center, and that study's lead author.

The first symptom of Alzheimer's may be mild forgetfulness. As the condition progresses, it begins to interfere with patients' daily lives as they forget how to brush their teeth, change their clothes, or recognize once-familiar people. They become confused and agitated and eventually require constant care, according to the National Institute on Aging, a U.S. government agency.

Keywords: human genetics CALHM1 ApoE4' genetics genes alzheimer's geriatrics aging Drug Targets Hippocampus Alzheimers disease