with this observation, TG level was significantly higher in subjects with CETP*V than those with CETP*I.

Conflict of interest

The stratification Chi-square test, multivariable-adjusted logistic regression, and nonparametric MDR analysis all suggested a significant interaction between CETP and APOE associated with hTG for oldest-old female subjects. Although APOE*4 was not strongly associated with hTG in this population, when APOE*4 was analyzed together with CETP*V, more than a fourfold increase in hTG risk was observed for subjects with both risk alleles (Fig. 1).

Acknowledgments

We are indebted to the participants in the study and their families for their outstanding commitment and cooperation. The study was support- ed by the Beijing Nova program (Z121107002512058), the Natural Science Foundation of China (30972709, 81061120527, 81241082), the major funding from Beijing Hospital (BJ-2010-30), National Department Public Benefit Research Foundation by the Ministry of Health P. R. China (201302008) and 12th 5 year national program from the Ministry of Scientific Technology (2012BAI10B01) and the Key Clinical Program for the Affiliated Hospital of the Ministry of Health (10120101).

We failed to repeat the contribution of CETP for the risk of hTG and the interaction with APOE in our middle-aged controls, but found the impact of APOE alone on TC and LDL-c (data not shown). This might be because of the difference of physiological status between oldest-old and middle-aged groups. Oldest-old subjects are strong survivors by natural selection, including environmental, lifestyle, and aging factors, accompanied with different metabolic characteristics compared to middle-aged subjects, which is the highlight of the study. There might have been a complex mechanism between clinical parameters and longevity in that subjects who met the criteria for oldest-old demon- strated a diverse clinical status.

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