MTP Genotype and Allele Frequency in Centenarians, Offspring, and Controls:
The prevalence of the MTP rs2866164 SNP and genotype frequency among centenarians, offspring, and controls are presented in Figure 1A and B, respectively. As compared with Ashkenazi controls, the CC genotype was more prevalent in both centenarians and their offspring (p<.05, Figure 1A), but no significant differences were observed in CG or GG genotype prevalence among groups. When assessing allele frequency in all three groups,Life but was followed by a marked enrichment to near 60% by 90 years of age (Figure 3B), as predicted by the buffering hypothesis (18). Discussion: Here, we show that the prevalence of the MTP CC genotype is enriched in centenarians and their offspring, as compared with Ashkenazi Jew controls. Paradoxically, this genotype was associated with an unfavorable lipid profile, including greater concentrations of TG, VLDL, and chylomicrons, all known risk factors for cardiovascular and metabolic diseases. This paradox between phenotype and genotype is explained by the fact that the MTP CC genotype demonstrated a monotonic decline with aging until ~80 years of age, followed by a marked increase in centenarians, forming a U-shape pattern with aging. Offspring and individuals belonging to the control group with the MTP CC genotype across ages were then categorized by presence or absence of one or more known longevity genotypes {CETP (VV) [rs5882] (13), APOC3 (CC) [rs2542052] (14), and AdipoQ (del/del APM1+2019) [rs56354395] (15)}. Absence of these genotypes resulted in a monotonic decline in CC prevalence to near 0% by 90 years, whereas a sharp rise in prevalence was observed in those harboring longevity genotypes beyond 80 years old. Finally, we show that control and offspring without any of the three favorable longevity genotype variants but possessing MTP CC genotype and Survivorship in Ashkenazi Offspring and Controls Kaplan Meier curves comparing survivorship between MTP genotypes are presented in Figure 4A and B. As compared with Ashkenazi offspring and controls with either CG/GG genotypes, those with the CC genotype demonstrated significantly worse survival (p < .05, Figure 4A). Table 2. Demographic and Metabolic Characteristics of Ashkenazi Offspring and Controls Categorized by MTP Genotype Percentage in group (%) >woPercentage in group (%)60[= Controlc OffspringCi Proband            5040302010cc CG GG70605040302010[= ControlOffspringC= Proband  p Value, CC vs CG/GG Trait CC, n = 113 CG/GG, n = 320 * Female (%) 51 59 .15 .14 Age, y 70.2 0.8 73.1 0.5 .004 .004 Age range, y 44-92 49-93 Glucose, mg/dL 90-4 95-2 .25 .26 Insulin, mg/dL 19.2-3.2 20.8-2.3 .68 .33 CRP 0.39-0.07 0.37-0.04 .73 .53 Cholesterol, mg/dL 204-4 203-2 .78 .61 Apo-A1, mg/dL 154-3 157-2 .45 .42 Apo-B, mg/dL 105-3 102-2 .37 .40 VLDL particle size, nm 48.9-1.7 47.6-0.8 .45 .54 LDL, mg/dL 117-4 116-2 .85 .54 LDL1, mg/dL 67.2-5.6 71.4-2.9 .47 .72 LDL3, mg/dL 32.8-4.2 28.2-2.3 .3 .46 LDL particle size, nm 20.9-0.1 21.0-0.1 .34 .77 HDL, mg/dL 59.5-1.7 60.8-1.1 .53 .4 Large HDL, mg/dL 28.8-2.1 32.1-1.2 .17 .72 Small HDL, mg/dL 18.2-0.7 17.5-0.5 .66 .92 HDL particle size, nm 9.06-0.05 9.16-0.03 .15 .48 Downloaded from http://biomedgerontology.oxfordjournals.org/ at Ondokuz Mayis University on November 9, 2014 Notes: Data are expressed as means SE. Crude means are shown. TG, which were not normally distributed, were log-transformed for analysis but presented as untransformed raw values. HDL = high-density lipoprotein; LDL = low-density lipoprotein; VLDL = very low-density lipoproteins. p Values between CC carriers and CG/GG carriers adjusted for age and sex (glucose [mg/dL], insulin [mg/dL],We conclude that the CC genotype is not a longevity gene, despite its relative enrichment in Ashkenazi probands. Contrary to prior observations, the pattern of genotype frequency during aging shows that CC genotype prevalence begins to decrease at ages where the mortality rate is expected to increase (Figure 3A). However, individuals approaching exceptional old age show a marked enrichment in the CC genotype. This is not because this genotype suddenly becomes beneficial, but rather due to the buffering effect of longevity genotypes, which are also becoming enriched (Figure 3B). 

For example, comparing only case-control analysis between 60-year-old individuals and centenarians in our study, which are on opposite ends of the U-shape, would show that gene variants involved in lipoprotein metabolism play an important role in healthy aging and longevity. 

In summary, we show that enrichment of the MTP CC genotype in centenarians and their offspring, relative to controls, is misleading unless the pattern in genotype frequency during aging is observed. The CC genotype demonstrates all the hallmarks of a buffered-deleterious genotype. We also demonstrate that a functional consequence of the CC genotype in controls without longevity genes includes poorer survivorship. Finally, this study is a vital proof of concept for the importance of populating the age axis as well as accounting for buffering mechanisms when attempting to discern longevity genotypes from deleterious genotypes.

Funding:
This work has been supported by grants from the Paul Beeson Physician Faculty Scholar in Aging Award, the Ellison Medical Foundation Senior Scholar Award, the General Clinical Research Center (M01-RR12248), and the Diabetes Research and Training Center (DK20541) at the Albert Einstein College of Medicine and grants AG027734, AG028872, RR12248, and M01RR12248 from the National Institutes of Health. D.M.H. is supported by a National Institute of Aging-sponsored K99 award (AG037574).