title: Genetic and environmental influences on thyroid hormone variation in Mexican Americans.
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.
authors.affiliation: Southwest Foundation for Biomedical Research, P.O. Box 760549, San Antonio, TX 78245-0549, USA. pbs@darwin.sfbr.org
authors.forename: Paul B
authors.initials: PB
authors.lastname: Samollow
authors.forename: Graciela
authors.initials: G
authors.lastname: Perez
authors.forename: Candace M
authors.initials: CM
authors.lastname: Kammerer
authors.forename: David
authors.initials: D
authors.lastname: Finegold
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Zwartjes
authors.forename: Lorena M
authors.initials: LM
authors.lastname: Havill
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Comuzzie
authors.forename: Michael C
authors.initials: MC
authors.lastname: Mahaney
authors.forename: Harald H
authors.initials: HH
authors.lastname: Göring
authors.forename: John
authors.initials: J
authors.lastname: Blangero
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Foley
authors.forename: M Michael
authors.initials: MM
authors.lastname: Barmada
mesh_terms: D000328:Adult; D000367:Age Factors; D001835:Body Weight; D004777:Environment; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008019:Life Style; D008297:Male; D017058:Mexican Americans / Q000235:genetics*; D008875:Middle Aged; D009043:Motor Activity; D015999:Multivariate Analysis; D010641:Phenotype; D011446:Prospective Studies; D012737:Sex Factors; D013739:Testosterone / Q000097:blood; D013963:Thyroid Hormones / Q000097:blood* / Q000235:genetics*
chemical_list: D013963:Thyroid Hormones; D013739:Testosterone