The discovery of a fat gene. Plus: Do swimming pools make you sick?

This week, Dr. Sydney Spiesel discusses a potential fat gene, the disappearance of medication to fight nausea, and whether swimming pools can make you sick.

A fat gene

Condition:   Obesity and heaviness may be the biggest problems, both medical and personal, afflicting people in wealthy parts of the world. Significantly overweight people have a high incidence of type 2 diabetes, heart disease, stroke, and high blood pressure. In addition to the obvious influence of growing up in a household with unhealthy eating habits, genes have been thought to play a role. Identical twins are very likely to have closely matched weights. Two children growing up in the same household are more likely to be of similar weight if they are biological siblings than if one or both are adopted.

New research: Now a group of mostly British researchers for the first time reports a likely candidate for a gene that plays a significant role in garden-variety obesity (as opposed to rare disorders for which genes have previously been identified). The research began as part of a project to identify gene variants associated with type 2 (sometimes called "adult-onset") diabetes. They compared variants in the genetic makeup of about 2,000 patients with type 2 diabetes with the genes of about 3,000 nondiabetic people in the United Kingdom. They found a high association between risk for type 2 diabetes and certain variants in a gene—FTO—on Chromosome 16. Since obesity is a strong contributor to the risk of developing type 2 diabetes, these researchers examined the relationship between the FTO gene variants and the heaviness of the diabetic patients.

Finding: They found a perfect match—and realized that FTO was associated with a propensity to be overweight rather than a direct cause of this form of diabetes. The researchers then expanded the scope of their study, adding almost 20,000 white European adults, both men and women. The studies confirmed that a quite common gene variant for the FTO gene was strongly associated with the risk for being overweight. And the risk rises even higher for the 16 percent of the population that carries two copies of this variant.

Caveat: We still have no idea about what role the FTO gene plays in the body or why it leads to excess pounds.

Conclusion: For too long, obesity has been seen as a moral failing, a weakness of will and self-control. In addition to giving us a new tool for understanding the mechanism of this condition, this new research establishes unequivocally that obesity is rooted in one's biology, not one's morals.

Fighting nausea

FDA decision: Last week, the FDA took trimethobenzamide suppositories—otherwise known as anti-nausea medication— off the market. The suppositories (Tigan is the most common brand) were chucked because, unlike forms of the same medication that can be taken orally or injected, they have not been demonstrated to be effective, except in a few small studies. Introduced more than 40 years ago, these suppositories were often used by primary care physicians and by emergency department doctors to manage the nausea of patients whose vomiting was so severe that they could not hold down oral medicines. Pediatricians use them also, but less so. In suppository form, as opposed to via injection, the medication can be given at home with a phoned-in prescription.

Problem: Usually I applaud taking medications off the market when they are shown to be ineffective (or, of course, harmful). But this time I am not so sure. In an e-mail, Dr. Robert Blank, a thoughtful internist friend, pointed out that Tigan suppositories are cheap and as effective as the other forms of the medication in his experience—mine, too. The patent for the medication has expired, so there is little economic incentive to do more rigorous testing. Without them, people will have to go to the ER for treatment when they cannot hold down oral anti-nausea meds. That will delay treatment, resulting in more dehydration and hospitalization. How serious is this problem likely to be? We really don't know, but here's a clue. Every year, about 30 million adults go to the ER for nausea and vomiting and more than 5 million are hospitalized. During the same year, we can expect well over 20 million pediatric cases of gastroenteritis (causing vomiting and diarrhea) resulting in 2 million physician visits, 220,000 hospitalizations, and about 500 deaths.