Submitted to: Obesity
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2006
Publication Date: 9/5/2006
Citation: Tejero, M.E., Cai, G., Butte, N., Lopez-Alvarenga, J.C., Mehta, N., Cole, S.A., Comuzzie, A. 2006. Pleiotropic effects between endocrine traits and energy expenditure in Hispanic children [abstract]. Obesity. 14:A197. Interpretive Summary:
Technical Abstract: The prevalence of obesity and related metabolic abnormalities in children and adolescents has escalated. Energy expenditure has been physiologically associated with thyroid hormones and adiposity-related hormones such as leptin and insulin. Genetic factors contribute to the regulation of energy expenditure and metabolic balance. The present investigation analyzed the presence of pleiotropic effects between thyroid hormones, insulin and leptin levels and phenotypes of energy expenditure including total energy expenditure (TEE), basal metabolic rate (BMR), sleeping energy expenditure (SEE) and cycling energy expenditure (CEE). We investigated the genetic factors influencing this group of traits in 1030 Hispanic children participating in the Viva la Familia Study. Hispanic families with at least one overweight child between the ages of 4 to 19 years were included in this investigation. A blood sample was collected under fasting conditions for analyses of circulating levels of free (FT3) and total triiodothyronine (TT3), free (FT4) and total thyroxine (TT4), thyroid stimulating hormone (TSH), insulin and leptin using reference methods. Energy expenditure respiratory quotient (RQ), and substrate utilization were measured by 24-h room respiration calorimetry. Anthropometric measurements were performed by standard methods. Body composition was measured by DEXA. Quantitative genetic analyses were conducted using the variance decomposition approach in the SOLAR software. EE phenotypes were normalized for body composition using allometric or power function models. Significant heritabilities were observed for levels of hormones and traits for energy expenditure. Significant genetic correlations were observed between FT3 and fat and carbohydrate utilization (rG =0.32, p=0.001 and rG = -0.32, p=0.001, respectively), BMR RQ and TEE RQ (rG =0.37, p= 0.003) and (rG = 0.27, p =0.006). Insulin showed a significant rG with TEE (rG = 0.47, p=0.0003), CEE (rG = 0.54, p=0.0002) and SEE (rG = 0.59, p =7.3 x 10 -10). Leptin levels were genetically correlated with TEE (rG= 0.62, p=1.4 x10-7) and CEE (rG = 0.49, p=0.0006). Significant genetic correlations indicate that a common gene or set of genes influences energy expenditure and substrate utilization, and fasting insulin, leptin and thyroid hormones.