Associations between uncoupling protein 2, body composition, and resting energy expenditure in lean and obese African American, white, and Asian children.
BACKGROUND
Little is known about genes that affect childhood body weight.


OBJECTIVE
The objective of this study was to examine the association between alleles of the mitochondrial uncoupling protein 2 (UCP2) gene and obesity because UCP2 may influence energy expenditure.


METHODS
We related UCP2 genotype to body composition and resting energy expenditure in 105 children aged 6-10 y. Overweight children and nonoverweight children of overweight parents were genotyped for a 45-base pair deletion/insertion (del/ins) in 3'-untranslated region of exon 8 and for an exon 4 C to T transition.


RESULTS
Eighty-nine children were genotyped for the exon 8 allele: 50 children had del/del, 33 had del/ins, and 6 had ins/ins. Mean (+/-SD) body mass index (BMI; in kg/m(2)) was greater for children with del/ins (24.1 +/- 5.9) than for children with del/del (20.4 +/- 4.8; P < 0.001). BMI of ins/ins children (23.7 +/- 7.8) was not significantly different from that of del/ins children. A greater BMI in del/ins children was independent of race and sex. Body composition was also different according to UCP2 genotype. All body circumferences and skinfold thicknesses examined were significantly greater in del/ins than in del/del children. Body fat mass as determined by dual-energy X-ray absorptiometry was also greater in del/ins than in del/del children (P < 0.005). For 104 children genotyped at exon 4, no significant differences in BMI or body composition were found among the 3 exon 4 genotypes. Neither resting energy expenditure nor respiratory quotient were different according to UCP2 exon 4 or exon 8 genotype.


CONCLUSIONS
The exon 8 ins/del polymorphism of UCP2 appears to be associated with childhood-onset obesity. The UCP2/UCP3 genetic locus may play a role in childhood body weight.
Yanovski
J A
JA
Unit on Growth and Obesity, Developmental Endocrinology Branch, National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892-1862, USA. jy15i@nih.gov
Diament
A L
AL
Sovik
K N
KN
Nguyen
T T
TT
Li
H
H
Sebring
N G
NG
Warden
C H
CH
D044466:Asian People / Q000235:genetics; D044383:Black People / Q000235:genetics; D001823:Body Composition; D001824:Body Constitution; D015992:Body Mass Index; D002648:Child; D004734:Energy Metabolism; D005091:Exons; D005260:Female; D005838:Genotype; D006801:Humans; D007473:Ion Channels; D008297:Male; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D009154:Mutation; D009765:Obesity / Q000235:genetics* / Q000503:physiopathology; D011506:Proteins / Q000235:genetics*; D044469:Racial Groups / Q000235:genetics*; D012146:Rest; D000071246:Uncoupling Protein 2; D044465:White People / Q000235:genetics; D001741:Black or African American
D007473:Ion Channels; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; C000604389:UCP2 protein, human; D000071246:Uncoupling Protein 2