Scientists close in on genes for anorexia, bulimia
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Researchers may be zeroing in on some of the genes that increase a person’s vulnerability to the eating disorders anorexia and bulimia.
In two new studies, an international research team identified several “core traits,” such as a tendency towards anxiety or perfectionism, that are commonly seen in people with the eating disorders, and that are to some degree inherited. The researchers then traced these traits to regions on particular chromosomes that, the studies suggest, may influence susceptibility to anorexia or bulimia.
Both studies were published online by the American Journal of Medical Genetics, in its neuropsychiatric genetics edition.
Though cultural pressures to be thin are thought to contribute to anorexia and bulimia, research on families and twins indicates eating disorders have strong genetic influences. For example, women with a mother or sister with a history of anorexia have elevated risks of anorexia and bulimia.
But hunting down the specific genes involved in any complex disorder, whether anorexia or heart disease, is a complicated task.
In the new studies, Dr. Walter H. Kaye of the University of Pittsburgh and his colleagues used data from about 400 families in which multiple members suffered from an eating disorder. Out of more than 100 behaviors and personality traits thought to contribute to anorexia and bulimia, the researchers settled on six “core” characteristics that seem to be key to eating disorder risk, and are to some extent heritable.
These included perfectionism, anxiety and age at first menstrual period, and, to a less consistent degree, concern over mistakes, food-related obsessions and lifetime minimum body weight.
The researchers then performed a gene-hunting technique called linkage analysis to see whether they could zero in on regions in the genome that may sway the risk of anorexia and bulimia.
They found that areas on several chromosomes showed significant links to bulimia, and lesser, “suggestive” links to anorexia—indicating that genes lying in these chromosomal regions may confer susceptibility to the eating disorders.
There was relatively little overlap in the chromosomal regions tied to the two eating disorders. This, according to Kaye’s team, suggests that although anorexia and bulimia are related, they may differ substantially at the genetic level.
For example, they note, an area of chromosome 10 that was linked to bulimia, but not anorexia, also overlaps with a region that has been linked to obesity. This is of interest, the researchers explain, because families affected by bulimia also tend to have higher-than-average rates of obesity, while the same is not true of anorexia-affected families.
On the other hand, there was evidence that certain genes—including those in a chromosomal region linked to obsessiveness—may confer susceptibility to both anorexia and bulimia.
The findings lay the groundwork for pinpointing specific genes involved in the eating disorders, which, experts hope, will ultimately improve treatment.
SOURCE: American Journal of Medical Genetics Part B, online September 8, 2005.
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