y_chromosome_heart_disease Image courtesy of iStockphoto/luckyraccoon
Men tend to get coronary artery disease much earlier than do women. For some men, the reason for that might be in part because of their fathers and their father’s father according to a new study, published online Wednesday in The Lancet.
The study analyzed data from 3,233 unrelated white men enrolled in previous U.K. studies. From this information, the researchers took a close look at genetic markers on the Y chromosome, which is passed on from father to son. They found that 15 to 20 percent of the men fell into one of the 13 ancient ancestry branches known as haplogroup I.
Men in this haplogroup, who all showed a common variant on the Y chromosome, were 50 percent more likely to have coronary artery disease than those without it even when age, body mass, cholesterol, high blood pressure, smoking and other risk factors were taken into account. The genetic link is not entirely surprising, given that heart disease has been known to run in families, but the finding adds support to previously observed trends and insights into additional lines of research.
The finding follows well-described geographic distribution of coronary artery disease. Haplogroup I has been traced back to hunter-gatherers who arrived in Europe from the Middle East some 25,000 years ago and who today remain more prevalent in the northern areas of western Europe, where incidence of coronary artery disease is still higher than it is in the south where the haplogroup R1b1b2 is more common.
The genetic variant came with altered patterns of regulation in 19 key pathways all of which were linked to immune and inflammatory responses. These differences might play a role in atherosclerosis, or the hardening of the arteries, noted the researchers, who were led by Fadi Charchar, of Australia’s University of Ballarat. “Dysfunction of immune response is a well established contributor to atherosclerosis and coronary artery disease,” they wrote. Previous research had found other immuno differences in men from this haplotype, such as HIV-positive men in this group taking longer to show an immune response after getting antiretroviral therapy.
The findings do not suggest that heart disease risk for men is entirely or even mostly lodged on the Y chromosome. And the researchers noted that knowing which haplogroup a man is from is unlikely to yield predictions of his individual risk of coronary artery disease. But, as they pointed out, a better understanding of this widespread association “could have important public health implications,” especially in attempts to assess the prevalence of the disease within a population. And further study should help “to decipher complex interplay between human Y chromosome, immunity and cardiovascular disease,” the researchers wrote.
“These findings are exciting,” Virginia Miller of the Mayo Clinic wrote in an associated Lancet essay (Miller was not involved in the new research). The new work also suggests that there could be another side to the genetic equation that is protective, she added.
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The last time I considered Barack Obama’s re-election chances in this magazine, in mid-November, things were looking pretty bleak for the president. The statistical model I used measured three key factors — a president’s approval rating, economic growth and the ideological orientation of his opponent — and taken together, they showed that Obama had become a slight underdog to win re-election. Three months later, his position is much stronger. In January, 243,000 jobs were created. The number surprised investors and economists, but it was part of a stream of solid economic data: over the last few months, consumer confidence has gone up, Americans have spent more on big-ticket items like cars and there is even evidence that the housing market has begun to rebound. Before the job numbers came out, most economists were expecting around 2.5 percent G.D.P. growth this year. Those forecasts are liable to be revised upward now, perhaps to about 3 percent. Americans seem to have noticed the change. By early February, Obama’s approval rating had climbed to 49 percent in the Real Clear Politics average, a six-point improvement from three months earlier. Although it’s not a terrific approval rating, it may be enough to get Obama another term. In 2004, George W. Bush won a narrow victory with essentially identical metrics: G.D.P. growth of 2.9 percent and an approval rating of about 48 percent on Election Day. Still, Obama’s position isn’t solid enough for him to beat just anybody. Bush benefited from running against a middling opponent like John Kerry, against whom he was able to squeeze every ounce out of his approval rating. The model I created evaluates the strength of the opposition candidate by considering his ideology on a left-to-right scale. Candidates who are closer to the center have historically done better than those closer to the wings. (I’ve updated the model’s measure of ideology to account for new data.) Obama’s most likely Republican opponent, Mitt Romney, continues to rate as a “generic Republican.” In fact, he now scores at exactly 50 on the 100-point scale from centrist to extremist. That means an election against Romney, like Bush’s against Kerry, would mostly be dictated by the fundamentals of the economy and by evaluations of Obama’s job performance. With 2.5 percent G.D.P. growth from now through November, Obama would be a 60 percent favorite to win the popular vote. The popular vote is one thing, however. The Electoral College is another — and Romney could have more vulnerabilities there. In recent weeks, Obama has taken a more populist approach (just read the transcript of his State of the Union address). The strategy has induced more howls than usual from Republicans about “class warfare,” but the White House has clearly studied the numbers. In the Republican primaries, Romney has had trouble winning the loyalty of working-class voters, especially in the Midwest. And recent polls suggest that Romney, who has a penchant for making intemperate comments that draw attention to his wealth, could struggle among that group in the general election as well. So let’s conduct a thought experiment. Suppose that against Romney, Obama does 10 points better among white voters whose households make less than $50,000 per year. The trade-off is that he does 10 points worse among whites making $100,000 or more and 15 points worse among whites making at least $200,000. In terms of the popular vote, this would almost exactly balance out. The effect would be more substantial, however, in individual states. In wealthy Virginia, Obama would lose a net of 2.5 percentage points to Romney under these rules, according to the demographics from the 2008 exit poll there. He would also be harmed by 2.7 points in Colorado. And Romney would have a chance of putting New Jersey into play, because he would gain four full points there. (The Chris-Christie-for-V.P. train will be departing from Platform 1.) 