Racial differences in the relation between uncoupling protein genes and resting energy expenditure.
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.
Kimm
Sue Y S
SY
Department of Family Medicine and Clinical Epidemiology, School of Medicine, University of Pittsburgh, PA 15261, USA. kimm@pitt.edu
Glynn
Nancy W
NW
Aston
Christopher E
CE
Damcott
Coleen M
CM
Poehlman
Eric T
ET
Daniels
Stephen R
SR
Ferrell
Robert E
RE
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
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