Anorexia nervosa is a complex disorder, a combination of genetic predisposition and environmental and behavioral factors. A recent study looked at 152 genes that are known to be involved in eating behavior, dopamine function, and brain communication to look for genetic variations that might be associated with Anorexia. Three groups of research subjects were looked at for a total of 1205 case subjects and 1948 controls. Results from the study linked anorexia with two genes: ESR2 and EPHX2
ESR2 is an estrogen receptor. Estrogen receptors are found in both men and women, but play a higher role for women, particularly starting in adolescence. Anorexia is more common in women, and typically develops around the start of puberty, so the connection here at least follows logically. It may come to some as a surprise that men also can have anorexia, and men also need a small amount of estrogen for strong bones and brain function.
EPHX2 ‘s connection is not as obvious. The gene codes for the epoxide hydrolase protein which is involved in the breakdown of fats and toxins. EPHX2 is involved in cholesterol metabolism, and defects in the gene are associated with a disease called familial hypercholesterolemia. Anorexia nervosa patients often display hypercholesterolemia, which is counterintuitive, given the under-nutrition and low body weight of affected individuals. The study says, “It has been hypothesized that low levels of cholesterol may decrease the activity of serotonin receptors and transporters and that signiﬁcantly lower cholesterol levels are associated with depressive symptoms, impulsive/self-harmful behavior (cutting and/or burning) and suicide thoughts/attempts in anorexia patients. Moreover, lower cholesterol levels have been associated with increased suicidality more broadly, including ideation and attempts, in depressed patients.”
Dr. Schork, one of the paper’s authors said, “The hypothesis would be that in some anorexics the normal metabolism of cholesterol is disrupted, which could influence their mood as well as their ability to survive despite severe caloric restriction.”
The study hopes that their results will provoke interest and more research into the connection between these genes and anorexia. It’s exciting news for researchers studying eating disorders.
Here’s the link to the article: