FAQ: New Alzheimer's Gene
Researcher Answers Questions About the Newly Discovered Alzheimer's Genetic Risk Factor, CALHM1
What would you say to people who think, "If there is this genetic risk factor, should I get a genetic test?"
I wouldn't rush to this right now. It's like the ethical issues related to ApoE4 testing. Is it too early or not? I would say yes. There is no preventive or curative treatment right now for Alzheimer's disease. There are some drugs that are working great, but they don't cure the disease. The idea to have a diagnostic [genetic test] today may not help too much.
But in the future, definitely, when we will understand the whole susceptibility for the disease, definitely CALHM1 [and] ApoE4 should be included and should be considered very seriously when we want to have a comprehensive diagnostic [genetic test] for people.
Besides CALHM1 and ApoE4, how many other genes do you think affect Alzheimer's risk?
There are, I would say, 20 genes -- 20 risk factors -- that show significance in increasing the risk of developing the disease. So ApoE4 and CALHM1 are not the only ones, but they are the most robust at this point.
But these numbers are changing every day because the more populations are added to the screenings, the more information we get on the exact number for the susceptibility genes. Some susceptibilities may be more specific to [certain ethnic groups], so this has to be carefully analyzed and combined.
Can you explain how you identified CALHM1?
We used a computer-based approach. ... This approach focused on the identification of genes that are specifically expressed, specifically working in the hippocampus. The hippocampus is a small region of the brain critical for memory formation and memory retention. What we know from the histopathology of the disease -- analysis of the disease progression in the brain -- we know that this region is affected very early during the course of the disease.
Right now, if you look at the literature, you have a lot of candidates for susceptibility for Alzheimer's disease. There is an urgent need to narrow down the number of candidates, and by using this computer approach, we were able to narrow down the list to a few candidates, and one of them was the one we recently published, this calcium channel. And we have six more candidates that we're currently investigating, and we are hoping that one of these candidates will be also significantly associated with the disease so we can get a better understanding of the overall genetic susceptibility for the disease.