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Peroxisome proliferator-activated receptor gamma (PPAR gamma) and peroxisome proliferator-activated receptor delta (PPAR delta) are promising candidate genes for obesity. Associations between adiposity-related phenotypes and genetic variation in PPAR gamma (Pro12Ala and C1431T), as well as PPAR delta (T+294C) were assessed in 2,102 Greek children aged 1-6 years, as part of a large-scale epidemiological study (Growth, Exercise and Nutrition Epidemiological Study In preSchoolers). In girls aged 3-4 years, the Ala12 allele was associated with higher mid-upper arm (P = 0.010) and hip (P = 0.005) circumferences, as well as subscapular (P = 0.008) and total skinfolds (P = 0.011) that explained 2.0, 3.7, 2.1, and 1.9% of the phenotypic variance, respectively, while the T1431 allele was associated with higher mean values for waist circumference (P = 0.018) and suprailiac skinfold (P = 0.017), genotype accounting for 1.6% of the variance in both phenotypes. No significant effects of PPAR delta T+294C polymorphism or the interaction of the PPAR delta and PPAR gamma variants on adiposity-related phenotypes were observed in any age group or gender. Haplotype-based analysis including both PPAR gamma polymorphisms revealed that in girls aged 3-4 years, the Ala-T haplotype was associated with higher waist (P = 0.014) and hip (P = 0.007) circumferences compared to the common Pro-C haplotype. The PPAR gamma Pro12Ala and C1431T polymorphisms are associated with increased adiposity during early childhood in a gender- and age-specific manner and independently of the PPAR delta T+294C polymorphism.

Objectives: To investigate the relationship between the angiotensin I-converting enzyme 1 (ACE) I/D polymorphism and adiposity-related phenotypes in a large cohort of toddlers and preschoolers., Methods: Body composition measurements and DNA samples were obtained from 2102 Greek children aged 1-6 years, as part of a large-scale epidemiological study (GENESIS). All children were genotyped for the ACE I/D polymorphism and gender- and age-stratified statistical analyses were performed., Results: In girls aged 4-6 years, the D-allele was associated with higher measurements of body mass index (BMI) (P=0.018), waist (P=0.001) and upper arm (P=0.013) circumferences, genotype accounting for 2.5, 4 and 3% of the phenotypic variance, respectively. In boys, the D-allele showed strong associations with lower BMI (P=0.001) at the age of 1-2 years that explained 17% of the phenotypic variance and with larger suprailiac skinfold (P=0.008) at 3-4 years old that explained 2% of the variance. No other significant associations between the ACE I/D polymorphism and adiposity-related phenotypes were found. In girls, the age at which significant associations were revealed coincided with the age at which BMI was observed to increase after its developmental nadir, but this feature of the association was not observed in boys., Conclusions: The ACE I/D polymorphism is associated with developmental and physiological changes in adiposity-related traits during early childhood in a gender- and age-specific manner.