Scientists at The Children's Hospital of Philadelphia have identified both common and rare gene variants associated with the eating disorder anorexia nervosa. In the largest genetic study of this psychiatric disorder, the researchers found intriguing clues to genes they are subjecting to further investigation, including genes active in neuronal signaling and in shaping interconnections among brain cells.
Anorexia nervosa (AN) affects an estimated 9 in 1000 women in the United States. Patients have food refusal, weight loss, an irrational fear of weight gain even when emaciated, and distorted self-image of body weight and shape.
Women are affected 10 times more frequently than men, with the disorder nearly always beginning during adolescence. AN has the highest mortality rate of all psychiatric disorders, and successful treatment is challenging.
Twin studies and other family studies have suggested that AN is strongly heritable. "However, despite various genetic studies that identified a handful of candidate genes associated with AN, the genetic architecture underlying susceptibility to AN has been largely unknown," said study leader Hakon Hakonarson, M.D., Ph.D., director of the Center for Applied Genomics at The Children's Hospital of Philadelphia. The research appeared online in Molecular Psychiatry on Nov. 16.
"This is the first genome-wide association study on a large anorexia cohort, as well as the first study of copy number variations in the disorder," said Hakonarson. Genome-wide association studies (GWAS) search for single-nucleotide polymorphisms, or SNPscommon gene variants that typically act as pointers to a gene region with a small effect on raising disease risk. The study team also performed a parallel search for copy number variations (CNVs), rarer variants that usually have a stronger impact on disease risk.
The sample size was the largest used in an AN gene studyDNA came from 1,003 AN patien
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Children's Hospital of Philadelphia