Phenotypes, endophenotypes, and genotypes in bulimia spectrum eating disorders.
OBJECTIVE
To review the main phenomenological variants observed among bulimia spectrum syndromes and the factors believed to act etiologically for them and also to generate an etiologic model that accommodates known heterogeneities within the population suffering bulimic syndromes.


METHODS
Defining bulimic syndromes broadly, we address threshold and subthreshold forms of bulimia nervosa (BN) and also the provisional or newly proposed diagnoses of binge eating disorder (BED) and purging disorder (PD). We review evidence bearing on the validity of these diagnostic entities and on the place of sociocultural, family-developmental, neurobiological, and genetic factors in a multidimensional etiologic model for these classifications.


RESULTS
Available data validate certain bulimic phenotypes and subphenotypes that are characterized by such traits as impulsivity or affective instability. Findings associate subphenotypic, or trait-based, variations with putative endophenotypes, such as reduced serotonin transporter activity, and with candidate genotypes affecting the serotonin system; the data also indicate intriguing correspondences between gene environment interactions and subphenotypic variations along such dimensions as novelty seeking.


CONCLUSIONS
Bulimic syndromes sometimes reflect a primary disruption of controls over mood, impulses, and appetite in individuals showing marked psychopathology; at other times, they reflect a more circumscribed erosion of appetitive controls in relatively intact individuals, following prolonged dieting. We argue that dimensional perspectives involving careful attention to comorbid personality traits and symptoms are needed to accommodate existing heterogeneities within the population suffering from bulimia and to characterize the etiologic roles of familial-developmental, neurobiological, and genetic variables (and of interactions among these variables) in bulimic syndromes.
Steiger
Howard
H
Psychiatry Department, McGill University, Montreal, Quebec. stehow@douglas.mcgill.ca
Bruce
Kenneth R
KR
D000483:Alleles; D052018:Bulimia Nervosa / Q000453:epidemiology / Q000235:genetics*; D015897:Comorbidity; D007174:Disruptive, Impulse Control, and Conduct Disorders / Q000453:epidemiology; D005838:Genotype; D006801:Humans; D018377:Neurotransmitter Agents / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D012701:Serotonin / Q000235:genetics / Q000378:metabolism; D012931:Social Environment
D018377:Neurotransmitter Agents; D012701:Serotonin