Genetic studies in eating disorders

Eating disorders (ED) are a group of psychiatric syndromes characterized by severe disturbances of eating behaviour, for which a common etiopathological background has been proposed. Familial and twin studies support the presence of a strong genetic component. ED have been considered to belong to the obsessivecompulsive spectrum. Obsessive-compulsive features are common in ED and it is possible to hypothesize a common genetic liability for both diseases. Dysregulation of serotonergic transmission may be involved in both ED and OCD, but involvement of other neurotransmitters cannot be excluded. Recently, a significant association between a functional polymorphism in the gene for catechol-O-methyltransferase (COMT) and susceptibility for OCD was found. We therefore decided to perform an association study using the COMT polymorphism (Val158Met) and the functional 44 bp insertion (allele D/deletion (allele s) in the serotonin transporter promoter (5HTTLPR). We screened 45 ED patients (44 females, 1 male) and 45 healthy controls matched for sex, of Italian descent. No statistically significant differences in allele (P = 0.516) or genotype (P = 0.283) frequencies were found for COMT polymorphisms. As regards the 5HTTLPR, we found a significant excess of both allele s (P = 0.023) and genotype ss (P = 0.017) in ED. These results suggest a possible role of the low-expressing 5HTTLPR variant and exclude a major role of the COMT variant in conferring susceptibility to ED. Replication in larger samples is clearly of critical importance.