Osteoporosis, fracture risk independent of APOE4 gene allele
MedWire News: Results from a meta-analysis refute the hypothesis that the apolipoprotein E (APOE) E4 allele significantly influences bone mineral density (BMD).
Lead author Inga Peter (Mount Sinai School of Medicine, New York, USA) and co-authors comment: “It is unlikely that carriers of the APOE4 allele are at greater risk for bone loss or require more aggressive therapies to prevent osteoporosis compared to those who are not carriers of the allele.”
Research in mice has indicated that animals lacking the low density lipoprotein receptor ligand APOE have greater bone formation due to a reduced osteoblast uptake of lipoproteins. In addition, the APOE4 allele has been linked to reduced BMD or increased risk for fracture compared with the E2 and E3 forms.
To investigate the link between BMD and APOE genotypes further, the team collated hip and lumbar spine BMD data and fracture history from two community cohorts, the Framingham Offspring Study comprising 1495 individuals and the vitamin K clinical trial with 377 participants, as well as 15 other studies.
Trochanteric BMD was a significant 0.018 g/cm2 lower in participants carrying APOE4 than those with other alleles. Lumbar spine BMD was also significantly reduced in APOE4 carriers compared with noncarriers, but this result was heterogenous between the studies.
The likelihood of reduced BMD was especially noted in women, the researchers say.
Furthermore, they caution in the journal Osteoporosis International that “these results were either based on a subset of the identified studies or are sensitive to single influential studies, and do not attain the stringent levels of statistical significance that are typically required for hypothesis forming research.”
The team adds that there was no significant relationship between carriage of APOE4 and BMD at other sites, or with the risk for hip, vertebral, or any site fractures in the studied populations.
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By Lynda Williams