Additive effect of LRP8/APOER2 R952Q variant to APOE ε2/ε3/ε4 genotype in modulating apolipoprotein E concentration and the risk of myocardial infarction: a case-control study

Abstract

Abstract Background The R952Q variant in the low density lipoprotein receptor-related protein 8 (LRP8)/apolipoprotein E receptor 2 (ApoER2) gene has been recently associated with familial and premature myocardial infarction (MI) by means of genome-wide linkage scan/association studies. We were interested in the possible interaction of the R952Q variant with another established cardiovascular genetic risk factor belonging to the same pathway, namely apolipoprotein E (APOE) ε2/ε3/ε4 genotype, in modulating apolipoprotein E (ApoE) plasma levels and risk of MI. Methods In the Italian cohort used to confirm the association of the R952Q variant with MI, we assessed lipid profile, apolipoprotein concentrations, and APOE ε2/ε3/ε4 genotype. Complete data were available for a total of 681 subjects in a case-control setting (287 controls and 394 patients with MI). Results Plasma ApoE levels decreased progressively across R952Q genotypes (mean levels ± SD = RR: 0.045 ± 0.020, RQ: 0.044 ± 0.014, QQ: 0.040 ± 0.008 g/l; P for trend = 0.047). Combination with APOE genotypes revealed an additive effect on ApoE levels, with the highest level observed in RR/non-carriers of the E4 allele (0.046 ± 0.021 g/l), and the lowest level in QQ/E4 carriers (0.035 ± 0.009 g/l; P for trend = 0.010). QQ/E4 was also the combined genotype with the most significant association with MI (OR 3.88 with 95%CI 1.08–13.9 as compared with RR/non-carriers E4). Conclusion Our data suggest that LRP8 R952Q variant may have an additive effect to APOE ε2/ε3/ε4 genotype in determining ApoE concentrations and risk of MI in an Italian population.