title: Racial differences in the relation between uncoupling protein genes and resting energy expenditure.
abstract: BACKGROUND
  Lower resting energy expenditure (REE) in African American women may contribute to their obesity. The identification of uncoupling protein (UCP) genes has fueled a search for genes involved in energy metabolism in humans.
  
  
  OBJECTIVE
  We examined variation in REE in relation to variation in UCP1, UCP2, and UCP3 in 141 women aged 18-21 y.
  
  
  METHODS
  Standard methods were used for REE measurements and genetic analysis. Body composition was determined with the use of dual-energy X-ray absorptiometry. Multivariate analysis was used to examine the effect of genotypes on REE and on fat mass in relation to other potentially confounding variables.
  
  
  RESULTS
  REE was 295 kJ/d lower in African American women than in white women. No significant variation in REE was seen for UCP1, UCP2, and UCP3 (p-55; exon 3a; and exon 3b) variants after adjustment for other variables including smoking status. For the UCP3 exon 5 variant, REE was significantly (P = 0.019) lower in African American women with the CC genotype than in those with the TT genotype. In African American women, there was a significant trend (P = 0.012) toward lower REE and a weak but nonsignificant trend (P = 0.1) toward greater fat mass across the 3 genotypes (TT, CT, and CC).
  
  
  CONCLUSIONS
  The significant and dose-dependent relation between lower REE and the C allele suggests that it may be a thrifty allele. The presence of this parsimonious energy metabolism in African American women, possibly linked to UCP3, may be implicated in their susceptibility to obesity. The absence of a UCP3 effect in white women is intriguing and needs to be explored to further understand possible interactions between UCP3 and other genes.
authors.affiliation: Department of Family Medicine and Clinical Epidemiology, School of Medicine, University of Pittsburgh, PA 15261, USA. kimm@pitt.edu
authors.forename: Sue Y S
authors.initials: SY
authors.lastname: Kimm
authors.forename: Nancy W
authors.initials: NW
authors.lastname: Glynn
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Aston
authors.forename: Coleen M
authors.initials: CM
authors.lastname: Damcott
authors.forename: Eric T
authors.initials: ET
authors.lastname: Poehlman
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Daniels
authors.forename: Robert E
authors.initials: RE
authors.lastname: Ferrell
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001481:Basal Metabolism / Q000235:genetics*; D044383:Black People; D015992:Body Mass Index; D002153:Calorimetry, Indirect; D002352:Carrier Proteins / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D007473:Ion Channels; D008137:Longitudinal Studies; D008565:Membrane Proteins / Q000235:genetics*; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D009765:Obesity / Q000235:genetics*; D011506:Proteins / Q000235:genetics*; D000071256:Uncoupling Protein 1; D000071246:Uncoupling Protein 2; D000071247:Uncoupling Protein 3; D044465:White People; D001741:Black or African American
chemical_list: D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; C000604371:UCP1 protein, human; C000604389:UCP2 protein, human; C000604392:UCP3 protein, human; D000071256:Uncoupling Protein 1; D000071246:Uncoupling Protein 2; D000071247:Uncoupling Protein 3