My MATERNAL grandmother had Alzheimer's disease. Before she died, she forgot our names, our faces and, eventually, how to speak and think.
But my grandfather's heartbreak was the most painful to witness. I remember watching the two of them on the sofa together in the months before she died. My grandfather, a sometimes severe man not overly disposed to expressions of tender emotion, cooed into my grandmother's ear: "My bride, oh my bride. I love you. Do you hear me? I love you." She just stared down blankly, folding napkins.
That scene was burning in my brain last week when I received an e-mail from a company that offers extensive genome scans directly to the public. The e-mail told me that my tube of spit had been analyzed and the results were in. I logged onto my account and began to scan the report for my estimated genetic risk for 17 diseases and c
Breast cancer, colon cancer, Type 2 diabetes: normal. Strangely relieving. Obesity: a little above average (I do not come from thin people).
Heart attack, multiple sclerosis, rheumatoid arthritis, macular degeneration: all a little below average. Even better.
And then there it was, in an orange "warning" box on my Web browser: a significantly higher-than-average lifetime risk for late-onset Alzheimer's disease, the most common type of this devastating disorder. The average risk of late-onset Alzheimer's is about 17%. Mine is 29%, owing to the DNA letters I carry in a gene called APOE, which contains coding instructions for a protein involved in processing cholesterol. It comes in different forms, or alleles -- and in my case, one of the copies I carry confers higher risk.
Before I could process a coherent thought, I burst into tears. Alzheimer's might be decades away for me -- I am not yet 30, and the late-onset disease strikes after 65 -- but that risk allele didn't pop up in my genome out of nowhere. In all likelihood it came from my mother, who just turned 60. My mother -- who already has high cholesterol, a known risk factor for Alzheimer's disease.
I was surprised by my reaction. It wasn't exactly news, was it? Family history alone told me that my mom is at higher risk of Alzheimer's just by being her mother's daughter. And the risk is not excessively high; this is by no means a guarantee that either of us will succumb to the disease.
But something about the plain and simple statement of my own genetic fact seemed shocking and terrifying.
