title: A DRD4/BDNF gene-gene interaction associated with maximum BMI in women with bulimia nervosa.
abstract: OBJECTIVE
  The goals of the current study were threefold: 1) to examine whether the hypofunctional 7R allele of the DRD4 gene contributes to maximal lifetime body mass in women with BN; 2) to determine whether the BDNF gene contributes to maximal BMI on its own, and 3) to explore possible BDNF/DRD4 gene-gene interactions in mediating maximum lifetime BMIs in BN.
  
  
  METHODS
  We tested two General Linear Models predicting maximum lifetime BMI with the exon 3 VNTR polymorphism of the dopamine-4 receptor gene (DRD4) and either the Val66Met or the -270C/T polymorphism of BDNF respectively in 163 female probands with BN, purging subtype.
  
  
  RESULTS
  In these bulimic subjects, the hypofunctional 7R allele of DRD4 predicted maximal BMI (p < .01). There was also a significant interaction between the DRD4 gene and the BDNF gene in predicting maximal BMI. The Val66Met rather than the 270C/T polymorphism of BDNF interacting with DRD4 predicted maximum BMI in this BN sample (p < .01). Probands carrying both the hypofunctional 7R allele of DRD4 and the Met66 allele of BDNF had significantly higher maximal BMI than did probands in the other gene-gene interaction groups.
  
  
  CONCLUSIONS
  These results provide further evidence that the hypofunctional 7R allele of DRD4 contributes to weight gain in women with BN and that the BDNF gene interacts with DRD4 to influence weight regulation in these subjects.
authors.affiliation: Eating Disorders Program, Toronto General Hospital, Toronto, Canada.
authors.forename: Allan S
authors.initials: AS
authors.lastname: Kaplan
authors.forename: Robert D
authors.initials: RD
authors.lastname: Levitan
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Yilmaz
authors.forename: Caroline
authors.initials: C
authors.lastname: Davis
authors.forename: Subi
authors.initials: S
authors.lastname: Tharmalingam
authors.forename: James L
authors.initials: JL
authors.lastname: Kennedy
mesh_terms: D000328:Adult; D000483:Alleles; D015992:Body Mass Index; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics*; D052018:Bulimia Nervosa / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D009765:Obesity / Q000453:epidemiology*; D011110:Polymorphism, Genetic / Q000235:genetics; D050638:Receptors, Dopamine D4 / Q000235:genetics*
chemical_list: D019208:Brain-Derived Neurotrophic Factor; C493599:DRD4 protein, human; D050638:Receptors, Dopamine D4