Genetic factors, specifically the
VKORC1 and
GGCX genes, have been shown to contribute to the interindividual variability in response to the vitamin K-antagonist, warfarin, which influences the dose required to achieve the desired anticoagulation response. These differences in warfarin sensitivity may be explained by differences in vitamin K status. Men and women (
n=416, 60-80 y), primarily of European descent, were genotyped for common polymorphisms in
VKORC1 and
GGCX. Cross-sectional associations exist between polymorphisms and biochemical markers of vitamin K [plasma phylloquinone, percent undercarboxylated osteocalcin (%ucOC)].
VKORC1 rs8050894 GG homozygotes had significantly higher cross-sectional measures of plasma phylloquinone than carriers of the CG or CC genotypes (plasma phylloquinone geometric means: GG 0.874±0.092 versus CG/CC 0.598± 0.044;
p=0.020), whereas carriers of
VKORC1 rs7294 AA or AG had significantly lower plasma phylloquinone concentrations compared to GG homozygotes (plasma phylloquinone geometric means: 0.579±0.045 versus 0.762±0.057;
p=0.035). Cross-sectional analyses also revealed that heterozygous carriers of
GGCX rs10187424 and
rs7568458 had significantly lower %ucOC relative to either homozygous group. Polymorphisms in genes encoding enzymes involved in vitamin K metabolism may modulate plasma concentrations of phylloquionone and percent carboxylation of osteocalcin.
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