Association of apolipoprotein E promoter polymorphisms with bone structural traits is modified by dietary saturated fat intake — The Cardiovascular Risk in Young Finns Study

Association of apolipoprotein E (APOE) ε4 allele with peripheral quantitative computed tomography (pQCT) bone traits at the distal and shaft sites of the radius and tibia was evaluated in the Young Finns Cohort (n = 1777). We also analyzed the interactions of the APOE promoter polymorphisms (−219G/T rs405509 and + 113G/C rs440446) and bone traits within the APOE ε3/ε3 genotype (n = 1025 and n = 1013, respectively), and investigated the gene–environment interactions on bone traits with longitudinal saturated fatty acids (SAFA) intake. Differences between the ε4 allele carriers and noncarriers were modest and mostly nonsignificant. Within the APOE promoter −219G/T polymorphism, cortical strength index (CSI) and compressive bone strength index (BSI) at the distal radius (linear, P = 0.003 and P = 0.05, respectively) and tibia (linear, P = 0.01 and P = 0.03, respectively), and CSI at the tibial shaft (linear, P = 0.04) decreased towards the −219T/T genotype in women. In men, total cross-sectional areas at the radial site and stress–strain index (SSI) at the radial shaft (linear, P = 0.03 and P = 0.04 and P = 0.05, respectively) increased, and conversely cortical bone density and CSI at the radial shaft (linear, P = 0.005 and P = 0.05, respectively) and CSI at the tibial shaft (linear, P = 0.03) decreased towards the −219T/T genotype. In the highest SAFA tertile, women with the −219T/T genotype had the smallest total area and SSI at the radial shaft (P = 0.01 and P = 0.02, respectively). Subjects with the APOE + 113C/C genotype shared similar bone traits as subjects with the APOE −219T/T genotype. In conclusion, APOE genotypes −219T/T and + 113C/C could be genetic markers for cortical bone strength. Furthermore, high longitudinal SAFA intake seems to be more detrimental to bone in women with the −219T/T and + 133C/C genotypes than others.

Research Highlights
► We examined the association of APOE gene polymorphisms and bone structural traits.
► Study population consisted of Finnish women and men aged 31–46 years.
► The APOE -219T/T genotype could be a genetic marker for lower cortical bone strength.
► Also the APOE +113C/C genotype may be related to lower cortical bone values.
► In women with the -219T/T and +113C/C genotypes, SAFA seems to be detrimental to bone.