Recent large studies point to 8 regions in the genome.
As previously described in Eating Disorders Review, a genome-wide association study (GWAS) showed further evidence of the genetic basis of AN, but this time with a twist. Areas of the genome linked to anorexia nervosa were also identified as being correlated with body mass index (BMI, kg/m2) and metabolic effects, as well as with psychiatric traits (Duncan et al., Am J Psychiatry. 2017; 174:850). A recent paper in Nature Genetics(Watson et al.) now combines the roughly 3500 cases used in that original GWAS with data from the eating disorders working group of the Psychiatric Genomics Consortium. That study yielded nearly 17,000 cases of people with AN, as well as data from around 55,000 controls. This greatly increases the researchers’ ability to examine genetic correlates of anorexia nervosa.
Eight loci are identified
The results confirm and extend evidence from the prior, much smaller, analysis. The GWAS study has identified eight significant loci, or regions within the genome. Analysis of the potential significance of those regions includes links to obsessive-compulsive disorder (OCD), major depressive disorder, schizophrenia, and anxiety. But, there were also links to metabolic factors, including factors that influence body mass index, physical activity, blood sugar, and high-density lipid cholesterol.
Taken together, these findings confirm and extend what has been known thus far. There appears to be some shared risk with anxiety symptoms of various sorts, including OCD, and with mood symptoms. On the other hand, the findings also support and extend the fascinating new perspective that variables related to metabolism are also relevant to risk for anorexia nervosa.
Of note, this very large study now begins to approach the size of samples used to uncover valuable genetic information in other illnesses such as schizophrenia mood disorders. However, there will be great value in collecting still much larger samples for furthering our understanding of anorexia nervosa and eventually other eating disorders as well.