Genotypes and Phenotypes of Anorexia Nervosa

Abstract

At present Anorexia Nervosa (AN) is diagnosed on the basis of phenotypes which are specified in DSM IV. It is argued that the nosology of the current diagnostic criteria lacks an empirical basis. Furthermore diagnosis based on phenotypes can be problematic since the symptoms needed for a diagnosis of AN may be attenuated or absent. Also, symptoms may change over the course of the illness. Intermediate phenotypes such as biomarkers (a biological marker) and endophenotypes may provide additional means to describe and identify these disorders. A variety of biomarkers or endophenotypes have been identified including: abnormalities in brain serotonin and dopamine networks; neuropsychological deficits, which include difficulties in executive function such as set-shifting and weak central coherence; and changes in the structure of the brain. Genes that make an individual susceptible to AN have also been investigated using linkage and association studies. Several loci have been identified which relate to serotoninergic, dopaminergic, opioidergic, and BDNF systems. At present many of these studies have been hampered by methodological limitations. Nevertheless, treatments tailored towards these traits are already being tested and show promise. It is hoped that continued investigation to identify potential biomarkers of AN may facilitate the early diagnosis and perhaps be of value in terms of prevention.