Vitamin D Receptor Gene Fok1 Polymorphism Predicts Calcium Absorption and Bone Mineral Density in Children

Authors

  • Sharla K. Ames,

    1. Children's Nutrition Research Center, U.S. Department of Agriculture/Agricultural Research Service, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, U.S.A.
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  • Kenneth J. Ellis,

    1. Children's Nutrition Research Center, U.S. Department of Agriculture/Agricultural Research Service, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, U.S.A.
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  • Sheila K. Gunn,

    1. Division of Endocrinology and Metabolism, Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, U.S.A.
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  • Kenneth C. Copeland,

    1. Division of Endocrinology and Metabolism, Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, U.S.A.
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  • Steven A. Abrams M.D.

    Corresponding author
    1. Children's Nutrition Research Center, U.S. Department of Agriculture/Agricultural Research Service, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, U.S.A.
    • USDA/ARS Children's Nutrition Research Center, 1100 Bates Street, Houston, TX 77030 U.S.A.
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  • This work is a publication of the U.S. Department of Agriculture (USDA)/Agricultural Research Service (ARS) Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, TX, U.S.A. This project has been funded in part with federal funds from the USDA/ARS under cooperative agreement number 58–6250–6-001, the National Institutes of Health (NIH), NCRR General Clinical Research for Children grant number RR00188, and grant NIH number AR43740. Contents of this publication do not necessarily reflect the views or policies of the USDA, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

Abstract

The vitamin D receptor (VDR) gene has been implicated as one of the major genetic components of osteoporosis. We evaluated the relationship between markers of mineral status and restriction fragment length polymorphisms of the VDR gene in 72 healthy children age 7–12 years. Using stable isotope techniques and dual-energy X-ray absorptiometry, we measured dietary calcium absorption, bone calcium deposition rates, and total body bone mineral density (BMD). The Fok1 polymorphism at the VDR translation initiation site was significantly associated with BMD (p = 0.02) and calcium absorption (p = 0.04). Children who were FF homozygotes had a mean calcium absorption that was 41.5% greater than those who were ff homozygotes and 17% greater absorption than Ff heterozygotes. BMD was 8.2% greater in the FF genotype than the ff genotype and 4.8% higher than the Ff genotype. These results suggest a substantial relationship between the VDR gene and bone metabolism at one or more levels, including dietary absorption of calcium and BMD in growing children.

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