Related Experiment Videos
Genetic and environmental influences on thyroid hormone variation in Mexican Americans
Paul B Samollow1, Graciela Perez, Candace M Kammerer
1Southwest Foundation for Biomedical Research, P.O. Box 760549, San Antonio, TX 78245-0549, USA. pbs@darwin.sfbr.org
Abstract:
Thyroid hormones play major roles in the regulation of a wide range of metabolic and physiologic processes, but the genes and environmental factors that affect normal, quantitative variation in thyroid hormone concentrations are largely unknown. Using quantitative genetic methods, we evaluated the effects of genes and environmental factors on thyroid hormone variation in 586 women and 425 men from 27 randomly ascertained Mexican-American families from the San Antonio Family Heart Study. Data were available on free and total T(4), free and total T(3), TSH, thyroglobulin, and T(4)-binding globulin, as well as on covariates, including sex, age, weight, lifestyle habits, physical activity, and others. These covariates accounted for 2-18% of total phenotypic variation, whereas genes accounted for 26-64% of the variation. Overall, free T(3) had the highest heritability, which is noteworthy because it is the most biologically active thyroid hormone and accounts for the vast majority of metabolic and physiologic effects of thyroid hormones. Our results indicate that genes account for a substantial portion of variation in human thyroid hormone levels, and suggest that further studies to identify the genes involved in this variation could reveal important insights into the processes that govern thyroid-mediated metabolism.
Related Concept Videos
Gene-Environment Interactions
Pharmacogenetic Phenotypes: Alterations in Pharmacokinetics, Drug Targets and Biologic Milieu
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
Synthesis and Regulation of Thyroid Hormones
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...
Background and Environment Affect Phenotype
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
Functions of Thyroid Hormones
TH is indispensable for the normal development and maturation of the skeletal, muscular, and nervous systems during fetal and childhood growth. It facilitates bone mineral turnover and regulates protein synthesis in developing tissues, contributing significantly to overall growth and...