title: Epistatic interaction between the monoamine oxidase A and serotonin transporter genes in anorexia nervosa.
abstract: The serotonin (5-HT) and norepinephrine (NE) systems are likely involved in the aetiology of anorexia nervosa (AN) as sufferers are premorbidly anxious. Specifically, we hypothesize that genes encoding proteins, which clear 5-HT and NE from the synapse, are prime candidates for affecting susceptibility to AN. Supporting our hypothesis, we earlier showed that the NE transporter (NET) and monoamine oxidase A (MAOA) genes appear to contribute additively to increased risk of developing restricting AN (AN-R). With regard to the MAOA gene, a sequence variant that increases MAOA activity and has suggested association with the anxiety condition, panic disorder was preferentially transmitted from parents to affected children. Here we provide evidence in support of interaction between the MAOA and serotonin transporter (SERT) genes in 114 AN nuclear families (patient with AN plus biological parents). A SERT gene genotype with no apparent individual effect on risk and known to be associated with anxiety is preferentially transmitted to children with AN (chi2 trend=9.457, 1 df, P=0.0021) and AN-R alone (chi2 trend=7.477, 1 df, P=0.0063) when the 'more active' MAOA gene variant is also transmitted. The increased risk of developing the disorder is up to eight times greater than the risk imposed by the MAOA gene variant alone--an example of synergistic epistatic interaction. If independently replicated, our findings to date suggest that we may have identified three genes affecting susceptibility to AN, particularly AN-R: the MAOA, SERT, and NET genes.
authors.affiliation: Department of Psychological Medicine, The Children's Hospital at Westmead, Westmead, NSW, Australia. RuthU@chw.edu.au
authors.forename: Ruth Elizabeth
authors.initials: RE
authors.lastname: Urwin
authors.forename: Kenneth Patrick
authors.initials: KP
authors.lastname: Nunn
mesh_terms: D000293:Adolescent; D000328:Adult; D000856:Anorexia Nervosa / Q000235:genetics*; D004843:Epistasis, Genetic; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D016015:Logistic Models; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000235:genetics*; D008995:Monoamine Oxidase / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010290:Parents; D016133:Polymerase Chain Reaction; D050486:Serotonin Plasma Membrane Transport Proteins
chemical_list: D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D008995:Monoamine Oxidase