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Bone Mineral Density in Patients with Apolipoprotein E Type 2/2 and 4/4
Genotype
T. Štulc, R. Češka, A. Hořínek, J. Štěpán
Third Department of Internal Medicine, First Faculty of Medicine, Charles
University, Prague, Czech Republic
Received October 3, 1999
Accepted January 6, 2000
Summary
The peak bone mass and the rate of bone loss are in part
genetically determined. It has been suggested that bone mineral density (BMD)
may be related to allelic variation in the apolipoprotein E (ApoE) gene locus. ApoE is important in the receptor-mediated clearance of chylomicron particles
from the plasma, Apo E4 having the highest and Apo E2 the lowest receptor
affinity. Chylomicrons are the main carrier of vitamin K in the plasma;
vitamin K plays an important role in the carboxylation of osteocalcin. We
have tested the hypothesis that persons with E4 variant would have lower BMD and
increased bone turnover than those with E2 variant. A total of 18 ApoE 2/2 and ApoE 4/4 homozygotes were selected from 873 patients who were examined for the ApoE genotype. BMD in lumbar vertebral, femoral neck and distal forearm was
measured and plasma concentrations of osteocalcin and C-terminal fragments of
collagen (CTx) were determined. BMD values (expressed as T-score) at the three
specified sites were –0.12± 1.72, –0.52±
1.32 and –0.52± 0.81 in ApoE 2/2 group and –0.24±
1.22, 0.00± 0.84 and –0.17±
1.07 in the ApoE 4/4 group. Plasma osteocalcin and CTx were within normal limits
in both groups. In conclusion, we did not observe any association of ApoE
genotype with BMD and biochemical markers of bone metabolism in ApoE 2/2 and ApoE 4/4 homozygotes.
Key words
Bone mineral density · Osteoporosis · Bone turnover · Apolipoprotein E · Vitamin K
Reprint requests
T. Štulc, M.D., Third Department of Internal Medicine, U nemocnice 1, 128 21
Prague 2, Czech Republic. Fax: 420-2-2496 2946. E-mail:
tstulc@lf1.cuni.cz
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