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The Vitamin D Receptor Start Codon Polymorphism ( Fok I) and Bone Mineral Density in Premenopausal American Black and White Women
Author(s) -
Harris Susan S.,
Eccleshall T. ROSS,
Gross Coleman,
DawsonHughes Bess,
Feldman David
Publication year - 1997
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1997.12.7.1043
Subject(s) - foki , femoral neck , bone mineral , medicine , endocrinology , genotype , calcitriol receptor , osteoporosis , bone density , polymorphism (computer science) , biology , vitamin d and neurology , genetics , gene
This study examines the association between bone mineral density (BMD) and a start codon polymorphism (SCP) at the translation initiation site of the vitamin D receptor (VDR) gene. The thymine/cytosine (T/C) polymorphism in the first of two start (ATG) codons can be detected by a restriction fragment length polymorphism (RFLP) using the endonuclease Fok I, which recognizes ATG as part of its restriction site. F indicates absence of the first ATG and a VDR that is shorter by three amino acids. The Fok I genotype was determined in 154 premenopausal American women (72 black and 82 white) who were 20–40 years old. BMD of the total body, femoral neck, and lumbar spine were measured by dual‐energy X‐ray absorptiometry. The distribution of the SCP genotypes differed significantly by race ( p < 0.001): 4% of blacks versus 18% of whites were ff homozygous and 65% of blacks versus 37% of whites were FF homozygous. There was no statistically significant interaction between race and SCP genotype in analyses of BMD at any skeletal site. In the group as a whole, the ff women had femoral neck BMD that was 7.4% lower than that of the FF women. The ff white women had total body BMD values that were 4.3% lower and femoral neck values that were 12.1% lower than FF white women. Total body and femoral neck BMD did not differ significantly by genotype in black women, and spine BMD did not differ by genotype in either race. Addition of the SCP genotype to analysis of covariance models comparing BMD of the black and white women reduced estimated differences in femoral neck BMD between the two groups by about 35%. In conclusion, the SCP polymorphism, detected with the endonuclease Fok I, appears to influence peak bone density, particularly at the femoral neck. Racial differences in its distribution may explain some of the racial difference in femoral neck BMD.