This week I brushed up on Parkinson’s disease. What drew me into this mini-review is an informative article, “Sergey’s Search,” that appeared in the July (print) issue of Wired and is now available on-line. The feature, by Thomas Goetz, offers insight on what it’s like to know that you’ve got a genetic disposition to Parkinson’s, details on some enzymes implicated in the illness and, further, considers what might be done to help future patients.
I recommend this article to any of my readers who are interested in genetics, Parkinson’s and/or what some even consider as a new era for health-related research.
There’s a lot to take in –
The Wired story starts with Google co-founder Sergey Brin. A Moscow native and, more recently, a California swimmer, Brin’s got his reasons for concern. He’s got a strong family history, for one thing: the illness has affected both his mother and aunt. It turns out Brin has a genetic disposition to develop the condition because he shares the disease-associated G2019S mutation with his mom. As Goetz explains, this alteration in the DNA segment of the gene encoding LRRK2, a leucine-rich repeat kinase, involves a single-nucleotide switch of an adenine for a guanine.
(I’ll add this, just in case you’re interested: the gene encoding LRRK2, or dardarin, resides at human 12q12 – that’s the long arm of chromosome 12. The G2019S nomenclature indicates that the mutation results in a change at the 2019th amino acid position along the protein’s encoded structure, so that a glycine, normally present, is replaced by a serine molecule at that spot. A fascinating tidbit, news to me today, is that when the gene was first cloned in 2004 the researchers, who’d studied several affected families of Basque origin, called it dardarin, derived from the Basque word dardara, meaning tremor.)
The G2019S mutation is relatively common among Ashkenazi Jews. Still, not all of those who carry the mutation develop the disease, and not all who have the disease have this particular mutation. Other genetic variants have been identified, and it’s not clear exactly how these wreak havoc with LRRK2’s function. Enzymes like LRRK2, a kinase, usually transfer ATP molecules from one protein to another. The presumption is that in Parkinson’s, abnormalities in this enzyme’s function – whether they’re caused by this particular mutation or another – somehow lead to loss of dopamine-producing cells in the brain.
Back to Sergey’s story –
“Brin didn’t panic,” Goetz reports (a point I’d emphasize too). Rather, he was reassured by his mother’s experience and high level of functioning with the disease. She still goes skiing (among other things one’s mother might do), he reasons.
What Brin is doing, along the lines of Goetz’s Decision Tree approach, is cutting his risk as best he can. He exercises regularly, doesn’t smoke, and funds research.
Like other rock star informaticists before him (think of Netscape founder James H. Clarke, who launched Healtheon and Steve Case, who started Revolution Health – these are my examples), Brin is struck by the slow pace of medical investigation:
“Generally the pace of medical research is glacial compared to what I’m used to in the Internet,” Brin says. “We could be looking lots of places and collecting lots of information. And if we see a pattern, that could lead somewhere.”
If only medical research could be more like Google…
Some clinical background:
Parkinson’s, a progressive and often debilitating neurological condition, affects a half million or so people in the U.S. As a practicing as a physician, I cared for many patients who had this illness. Although I would see them for other reasons, it was hard not to notice, and know, the characteristic tremor, rigidity and shuffling walk of those affected. The onset of symptoms is usually insidious, slow and unnerving.
As Goetz indicates, most of what doctors understand about Parkinson’s comes from observing patients in the clinic. Illness emerges, it’s thought, as the number of dopamine-producing cells in the brain diminishes. Dopamine is a neurotransmitter, a molecule that transmits messages between cells or groups of cells within the nervous system. Since around 1967, when the drug Levodopa was first marketed, doctors have prescribed this and other pills for people who have Parkinson’s. While these meds can ameliorate symptoms, these don’t reverse the unstoppable deterioration of body and, ultimately, the mind.
One problem with Parkinson’s research and treatment is that once the disease becomes evident, it’s hard – probably too late – to reverse the loss of dopamine-producing cells. Most people don’t develop symptoms until dopamine production is around 20 percent of normal levels. Now, with the advent of genetic markers and potential to “catch” this disease early on, there’s an opportunity for early intervention.
One promising area for Parkinson’s research:
LRRK2 is a kinase, a kind of enzyme that’s over-active in some cancers. Already, pharmaceutical companies have developed specific kinase inhibitors; a dozen or so are already FDA-approved for treatment of particular cancers, and many more are in the pipeline.
What excites me, in all of this, is the possibility that these drugs might be effective in patients with Parkinson’s disease. And because the same enzyme – LRRK2, or dardarin – is implicated in cases without the particular G2019S mutation, it may be that these drugs would work even in cases that lack this particular genetic feature. (There are examples in oncology, in terms of tumor genetics and responsiveness to targeted drugs, that would support this contention, but that’s just theory for now.) The bottom line, as I see it, is that these new drugs should be carefully tested in clinical trials.
One of the key ideas in Goetz’s piece has to do what he considers and may well be a revolutionary approach to medical research.
…Brin is after a different kind of science altogether. Most Parkinson’s research, like much of medical research, relies on the classic scientific method: hypothesis, analysis, peer review, publication. Brin proposes a different approach, one driven by computational muscle and staggeringly large data sets. It’s a method that draws on his algorithmic sensibility—and Google’s storied faith in computing power…
In what may indeed be a “fourth paradigm” of science, as attributed to the late computer scientist Jim Gray, there’s an inevitable evolution away from hypothesis and toward patterns.
As I understand it, Brin seeks to invert the traditional scientific method by applying Google-size data-mining power to massive and very imperfect data sets in health. Already, he and his colleagues have accomplished this by Google’s Flu Trends, which several years ago beat the CDC to an epidemic’s discovery by two weeks.
You should read this article for yourself, as I’m afraid I can’t adequately describe the potential powers of computational health and science analyses that might be applied to well, pretty much everything in medicine. This goes well beyond a new approach to finding a cure for Parkinson’s disease.
This story, largely based in genomics and computational advances, reflects the power of the human mind, how the gifted son of two mathematicians who fell into a particular medical situation, can use his brains, intellectual and financial resources, and creativity, to at least try to make a difference.
I hope he’s successful!