Genetic Study Of The Longevity And Longevity-related Phenotypes In Guangxi, China

Longevity is a complex trait with genetic inheritance, and a marker for healthy and successful aging. Recent studies demonstrated that the lifespan and aging is regulated by genes. Most of these genes are involved in energy metabolism as well as mostly highly conservative and located in nuclear and mitochondrial genome. Therefore, the systematic study of the role of nDNA and mtDNA genetic variants in healthy longevity and successful aging is very important to better understand the reason and mechanism of health longevity and to reduce the risk of aged-related diseases and improve the life quality of the elders.Objectives:To explore'the role of nDNA and mtDNA genetic variants in healthy longevity and successful aging, we analyzed the association of nDNA and mtDNA genetic variants with healthy longevity and successful aging, and employed a preliminary study on the function mechanism of nDNA and mtDNA genetic variants.Methods:1) By bioinformatics analysis, the mitochondrial genome and nuclear APOE gene are selected as the candidate genes associated with longevity.2) Through collecting the information of familial longevity and longevity-related phenotype and by case-control design, long-lived individuals who were 90 years old or above was selected as case sample and the local general population whose parents didn't survived to 90 years old or above was selected as control sample.3) Longevity-related phenotype analysis:the physiological or biochemical measurement index and longevity-related phenotype were compared between long-lived individuals and controls.4) The study of genes associated with longevity:identifying genes associated with longevity in population 1, and replicating genes associated with longevity in population 2 and 3.4.1) By sequencing whole mitochondrial genome, construct mtDNA phylogeny and identify mtDNA genetic variants associated with longevity.4.2) By genotyping APOE gene variants, detecting APOE gene variants associated with longevity in population 1.4.3) Replicating APOE gene variants associated with longevity in population 2 and 3, and conducting Meta-analysis in multi-populatipns.4.4) Exploring the interaction between APOE gene and mitochondrial genetics variants.5) Analyzing the effect of genes associated with longevity on the longevity-related phenotype.6) A preliminary study on the function of the mtDNA genetic variant associated with longevity.7) By a variety of statistical software packages, conducing genetic model analysis. Results:1)A total of 814"longevity" cases were classified as participants who had survived to age 90 years or more, with a total of 1136 "younger controls" less than 65 years of age, including 1012 Bama individuals(247 individuals in 2001 and 738 individuals in 2008) and 938 Yongfu individuals(in 2008). The ratio of female and male is 2.8:1.2) A total of 43 phenotypes were analyzed in this study. There were statistical significance for 7 phenotypes (SBP, DBP, FBG, TC, TG, LDL-C and BMI) between long-lived population and controls.3) By sequencing the whole mitochondrial genome, 225 mtSNPs and 25 mtDNA haplogroups were found in 20 long-lived individuals.4) Haplogroup F was found to be significantly more frequent in longevity cases (21.0%) than in local controls (13.5%) in Bama population in 2008. There were significantly statistical significance for haplogroup F between two groups (p=0.013), conferring approximately 1.7 times of the protective effect (OR:1.703,95%CI:1.153-2.514). 5)The three mtSNPs in haplogroup F m.3970C＞T, m.13928G>C, m.10310G>A) were found to be consistently associated with longevity(p=0.009, OR:1.602,95%CI: 1.134-2.262; p=0.021, OR:1.507,95%CI:1.075-2.114和1 p=0.01, OR:1.703,95%CI: 1.153-2.514).6) By the comparative analysis of rCRS sequence, the mutation m.13928G/C causes an amino acid change Ser531Thr in the MT-ND5 protein. According to the protein secondary-structure and hydrophilicity analysis, the Ser531Thr polymorphism is located in the loop structure between the 7th and 8th transmembrane helices and increases local hydrophilicity in the loop structure.7) The mtDNA phylogeny constructed showed long-lived populations could have originated from ancestor in South China.8) Compared to control subjects in Bama population in 2001, the homozygousε3/ε3 genotype frequency in long-lived population was significantly higher (78.9% versus 67.8%, p=0.04), whereas the heterozygousε3/ε4 genotype andε4 allele frequency were significantly lower (5.5%versus 13.7%, p=0.02, and 4.6%versus 10.6%, p=0.01). 9) Further replicate the association of APOE gene with longevity in Bama population in 2008 and Yongfu population in 2008. Results in Bama population in 2008 showed the APOEε3 allele and the APOE s3/s3 genotype in long-lived individuals is higher frequent than those in control subjects, positively associated with longevity (p=0.008, OR:1.427, 95%CI:1.095-1.859 and p=0.007, OR:1.530,95%CI:1.124-2.083), whereas APOEε4 allele and the APOEε3/ε4 genotype were significantly lower frequent than those in controls, negatively associated with longevity (p=0.004, OR:0.565,95%Cl:0.380-0.838 and p=0.044, OR:0.626,95%CI:0.396-0.991). Results in Yongfu population in 2008 indicated the APOEε3 allele and the APOEε3/ε3 genotype in long-lived individuals is higher frequent than those in control subjects, positively associated with longevity (p<0.01, OR:2.06,95%CI:1.52-2.78 and p<0.01,OR:2.16,95%CI:1.55-3.02), whereas APOEε4 allele and the APOEε3/e4 genotype were significantly lower frequent than those in controls, negatively associated with longevity (p<0.01,OR:0.29,95%CI: 0.18-0.49 and p<0.01, OR:0.32,95%CI:0.18-0.58).10) The results of meta-analysis in 14 populations suggestedε4-carriers (the s3/s4 andε4/ε4 genotypes) were positively associated with longevity and the APOE s3/s3 genotype was negatively associated with longevity. The combined ORs for APOEε4-carriers was OR=0.42,95%CI:0.36-0.49 and the combined ORs for APOEε3/ε3 genotype OR=1.47,95%CI:1.25-1.74.11) The effect of the interaction of mtDNA genetic variants and APOE gene on longevity was analyzed, suggesting among APOEε4-carriers, mtDNA haplogroup F was higher frequent in long-lived population than that in controls (28.9%vs 8.8%, p=0.010, OR:4.237, 95%CI:1.335-13.446).12) The relationship of FBG, TG, TC, HDL-C and LDL-C levels with mtDNA variants was tested. The results showed that there was a significant relation of TC and HDL-C levels to mtDNA variants. Haplogroup F, m.13928C and m.10310A were associated with markedly higher HDL-C levels, and m.13928C was associated with lower TC levels in long-lived cases. APOEε4-carrier was associated with significantly higher TC and LDL-C levels (p=0.003 and p=0.012), and APOEε3/s3 was associated with higher HDL-C levels (p=0.005) in long-lived individuals.Conclusions:1) The mtDNA haplogroup F was found to be associated with healthy longevity, conferring the protective effect.2) The three mtSNPs (mt3970C>T, mt13928G>C and mt10310G>A) were found to be associated with longevity, and an amino acid changes Ser531Thr (mt13928G/C) in the MT-ND5 gene might account for the beneficial effect of F.3) it was confirmed APOE gene associated with longevity in multi-population APOEε4 gene increased the risk effect for successful aging and longevity, whereas APOEε3 gene conferred protective effect for healthy longevity.4) There could be the interaction of haplogroup F and APOE s4 gene.5) The mtDNA and APOE genetic variants possibly influence healthy phenotype of long-lived individuals, such as TC, LDL-C and HDL.