As with most idiopathic psychiatric disorders, the inheritance of AN is complex. The core features of AN [i.e., the ability and determination to maintain low body mass index (BMI)] are remarkably homogeneous across time and cultures.24, 25 Genetic epidemiological studies have documented the familiality of AN (relative risk 11.3 in first-degree relatives of AN probands)26, 27 and the estimated twin-based heritability of AN ranges from 33 to 84%.28-32 Genome-wide linkage studies did not narrow the genomic search space in a compelling manner.33-35 Findings from candidate gene studies of AN resemble those for most complex biomedical diseases—initial intriguing findings diminished by the absence of rigorous replication.36-38
