title: Obesity related phenotypes in families selected for extreme obesity and leanness.
abstract: BACKGROUND
  Obesity is a multigenic trait, and special methods and sampling designs are needed for gene identification.
  
  
  OBJECTIVE
  To describe characteristics of families selected to increase information for genetic linkage studies of obesity.
  
  
  METHODS
  Families having extremely obese siblings with a lean parent and sibling.
  
  
  METHODS
  594 members of 94 Caucasian families.
  
  
  METHODS
  Measured height and weight, bioelectric impedance, skinfolds, circumferences and questionnaires.
  
  
  RESULTS
  Families have an extreme range of obesity phenotypes, which are bimodally distributed. The obese individuals are predominantly women with an onset of obesity early in life. Obesity onset age was negatively correlated with level of obesity, and onset ages were correlated among family members. Individual obesity measures were highly correlated. The extreme range of phenotypes within families increases family variability and presumably gene segregation.
  
  
  CONCLUSIONS
  Sampling families through extremely obese sibling pairs with a lean parent and sibling results in families with an extreme range of obesity and leanness. The large within-family variance and early age of onset should make these families highly informative for gene mapping and gene identification studies.
authors.affiliation: Center for Neurobiology and Behavior, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Price
authors.forename: D R
authors.initials: DR
authors.lastname: Reed
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D017097:Electric Impedance; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000235:genetics* / Q000503:physiopathology*; D010641:Phenotype; D012727:Sex Characteristics; D012885:Skinfold Thickness