Aging and genetic variation of plasma apolipoproteins. Relative loss of the apolipoprotein E4 phenotype in centenarians

Positive association of familial longevity with the moderate-high HDL-C concentration in Bama Aging Study

Familial longevity is characterized by beneficial metabolic phenotype in lipid metabolism and APOE genetic variation. Although effects of lipid metabolism and the genetic basis for human longevity remain largely unclear, the contribution of high-density lipoprotein cholesterol (HDL-C) and APOE ε2 allele has been repeatedly demonstrated. This study was designed to determine whether ApoE isoforms and HDL-C levels marked the familial longevity status in an offspring cohort with the age range of 20-89 years old and subsequently to explore the correlation between these two markers and the aging. In the Bama Aging Study (BAS), we recruited 312 offspring from longevity historical families and 298 controls from non-longevity historical families. Information on APOE genotype frequencies, lipid levels, and population characteristics were recorded. No evidence was found to support the association of APOE genotypes with HDL-C and age. HDL-C was significantly higher in longevity group (p < 0.0001). Scatter plot showed a moderately strong linear relationship between the HDL-C level and age in longevity group (r = 0.213, p < 0.001). We conclude that the variation of the APOE gene may not influence familial longevity status at a certain age but the moderate-high HDL-C level contributes to the familial longevity in Bama.

The impact of APOE genotype on survival: Results of 38,537 participants from six population-based cohorts (E2-CHARGE)

BACKGROUND

Apolipoprotein E is a glycoprotein best known as a mediator and regulator of lipid transport and uptake. The APOE-ε4 allele has long been associated with increased risks of Alzheimer's disease and mortality, but the effect of the less prevalent APOE-ε2 allele on diseases in the elderly and survival remains elusive.

METHODS

We aggregated data of 38,537 individuals of European ancestry (mean age 65.5 years; 55.6% women) from six population-based cohort studies (Rotterdam Study, AGES-Reykjavik Study, Cardiovascular Health Study, Health-ABC Study, and the family-based Framingham Heart Study and Long Life Family Study) to determine the association of APOE, and in particular APOE-ε2, with survival in the population.

RESULTS

During a mean follow-up of 11.7 years, 17,021 individuals died. Compared with homozygous APOE-ε3 carriers, APOE-ε2 carriers were at lower risk of death (hazard ratio,95% confidence interval: 0.94,0.90-0.99; P = 1.1*10-2), whereas APOE-ε4 carriers were at increased risk of death (HR 1.17,1.12-1.21; P = 2.8*10-16). APOE was associated with mortality risk in a dose-dependent manner, with risk estimates lowest for homozygous APOE-ε2 (HR 0.89,0.74-1.08), and highest for homozygous APOE-ε4 (HR 1.52,1.37-1.70). After censoring for dementia, effect estimates remained similar for APOE-ε2 (HR 0.95,0.90-1.01), but attenuated for APOE-ε4 (HR 1.07,1.01-1.12). Results were broadly similar across cohorts, and did not differ by age or sex. APOE genotype was associated with baseline lipid fractions (e.g. mean difference(95%CI) in LDL(mg/dL) for ε2 versus ε33: -17.1(-18.1-16.0), and ε4 versus ε33: +5.7(4.8;6.5)), but the association between APOE and mortality was unaltered after adjustment for baseline LDL or cardiovascular disease. Given the European ancestry of the study population, results may not apply to other ethnicities.

CONCLUSION

Compared with APOE-ε3, APOE-ε2 is associated with prolonged survival, whereas mortality risk is increased for APOE-ε4 carriers. Further collaborative efforts are needed to unravel the role of APOE and in particular APOE-ε2 in health and disease.

The Genetic Variability of APOE in Different Human Populations and Its Implications for Longevity

Human longevity is a complex phenotype resulting from the combinations of context-dependent gene-environment interactions that require analysis as a dynamic process in a cohesive ecological and evolutionary framework. Genome-wide association (GWAS) and whole-genome sequencing (WGS) studies on centenarians pointed toward the inclusion of the apolipoprotein E (APOE) polymorphisms ε2 and ε4, as implicated in the attainment of extreme longevity, which refers to their effect in age-related Alzheimer's disease (AD) and cardiovascular disease (CVD). In this case, the available literature on APOE and its involvement in longevity is described according to an anthropological and population genetics perspective. This aims to highlight the evolutionary history of this gene, how its participation in several biological pathways relates to human longevity, and which evolutionary dynamics may have shaped the distribution of APOE haplotypes across the globe. Its potential adaptive role will be described along with implications for the study of longevity in different human groups. This review also presents an updated overview of the worldwide distribution of APOE alleles based on modern day data from public databases and ancient DNA samples retrieved from literature in the attempt to understand the spatial and temporal frame in which present-day patterns of APOE variation evolved.

APOE Alleles and Extreme Human Longevity

We assembled a collection of 28,297 participants from seven studies of longevity and healthy aging comprising New England Centenarian, Long Life Family, Longevity Gene Population, Southern Italian Centenarian, Japanese Centenarian, the Danish Longevity, and the Health and Retirement Studies to investigate the association between the APOE alleles ε2ε3 and ε4 and extreme human longevity and age at death. By using three different genetic models and two definitions of extreme longevity based on either a threshold model or age at death, we show that ε4 is associated with a substantially decreased odds for extreme longevity, and increased risk for death that persists even beyond ages reached by less than 1% of the population. We also show that carrying the ε2ε2 or ε2ε3 genotype is associated with significantly increased odds to reach extreme longevity, with decreased risk for death compared with carrying the genotype ε3ε3 but with only a modest reduction in risk for death beyond an age reached by less than 1% of the population.

Exceptional Human Longevity

Exceptional longevity represents an extreme phenotype. Current centenarians are survivors of a cohort who display delayed onset of age-related diseases and/or resistance to otherwise lethal illnesses occurring earlier in life. Characteristics of aging are heterogeneous, even among long-lived individuals. Associations between specific clinical or genetic biomarkers exist, but there is unlikely to be a single biomarker predictive of long life. Careful observations in the oldest old offer some empirical strategies that favor increased health span and life span, with implications for compression of disability, identification and implementation of lifestyle behaviors that promote independence, identification and measurement of more reliable markers associated with longevity, better guidance for appropriate health screenings, and promotion of anticipatory health discussions in the setting of more accurate prognostication. Comprehensive PubMed literature searches were performed, with an unbiased focus on mechanisms of longevity. Overall, the aggregate literature supports that the basis for exceptional longevity is multifactorial and involves disparate combinations of genes, environment, resiliency, and chance, all of which are influenced by culture and geography.

Review and meta-analysis of genetic polymorphisms associated with exceptional human longevity

BACKGROUND

Many factors contribute to exceptional longevity, with genetics playing a significant role. However, to date, genetic studies examining exceptional longevity have been inconclusive. This comprehensive review seeks to determine the genetic variants associated with exceptional longevity by undertaking meta-analyses.

METHODS

Meta-analyses of genetic polymorphisms previously associated with exceptional longevity (85+) were undertaken. For each variant, meta-analyses were performed if there were data from at least three independent studies available, including two unpublished additional cohorts.

RESULTS

Five polymorphisms, ACE rs4340, APOE ε2/3/4, FOXO3A rs2802292, KLOTHO KL-VS and IL6 rs1800795 were significantly associated with exceptional longevity, with the pooled effect sizes (odds ratios) ranging from 0.42 (APOE ε4) to 1.45 (FOXO3A males).

CONCLUSION

In general, the observed modest effect sizes of the significant variants suggest many genes of small influence play a role in exceptional longevity, which is consistent with results for other polygenic traits. Our results also suggest that genes related to cardiovascular health may be implicated in exceptional longevity. Future studies should examine the roles of gender and ethnicity and carefully consider study design, including the selection of appropriate controls.

Assessment of the contribution of APOE gene variants to metabolic phenotypes associated with familial longevity at middle age

Offspring of long-lived families are characterized by beneficial metabolic phenotypes in glucose and lipid metabolism and low 25-hydroxyvitamin D. Although the genetic basis for human longevity remains largely unclear, the contribution of variation at the APOE locus has been repeatedly demonstrated. We aimed to assess whether ApoE isoforms mark the familial longevity status in middle age and subsequently to test to what extend this association is mediated by the metabolic characteristics marking this status. From the Leiden Longevity Study (LLS), we included offspring from nonagenarian siblings and partners as controls. Using the metabolic phenotypes of familial longevity as mediators, we investigated how APOE gene variants associated with LLS offspring/control status (in 1,515 LLS offspring and 715 controls). Within the LLS (mean age = 59.2 years), ApoE ε4 was not associated with a lower likelihood of being an LLS offspring, whereas ApoE ɛ2 was significantly associated with a higher likelihood of being an LLS offspring (odds ratio = 1.43), but this difference was not mediated (p-values>0.05) by any of the investigated metabolic phenotypes (e.g., diabetes and glucose). Therefore, variation at the APOE locus may not influence familial longevity status in middle age significantly through any of the metabolic mechanisms investigated.

Cognitive status in the oldest old and centenarians: a condition crucial for quality of life methodologically difficult to assess

Human life expectancy and the number of the oldest old are rapidly increasing worldwide. Advanced age is the main risk factor for dementia, representing one of the major causes of disability/dependency among older people with a strong impact on their families/caregivers. Centenarians have reached the extreme limits of human life escaping or delaying the major age-related diseases. Thus, these extraordinary individuals embody the best model to answer the crucial question if cognitive decline and dementia are progressive and unavoidable occurrences of increasing age. Despite a growing amount of data underlines the importance of cognitive function for quality of life and survival in old age, studies on centenarians have paid more attention to their physical condition rather than the assessment of their actual cognitive abilities. Accordingly, this work aims to summarize available data on the prevalence of dementia in centenarians and to critically address topics which can have a relevant impact on the cognitive assessment/status of the oldest old: (i) lack of standardized tools for cognitive assessment; (ii) criteria and threshold to establish the presence of dementia; (iii) influence of birth cohort and education; (iv) role of depression or positive attitude towards life; (v) gender differences.

Limitations and risks of meta-analyses of longevity studies

Searching for genetic determinants of human longevity has been challenged by the rarity of data sets with large numbers of individuals who have reached extreme old age, inconsistent definitions of the phenotype, and the difficulty of defining appropriate controls. Meta-analysis - a statistical method to summarize results from different studies - has become a common tool in genetic epidemiology to accrue large sample sizes for powerful genetic association studies. In conducting a meta-analysis of studies of human longevity however, particular attention must be made to the definition of cases and controls (including their health status) and on the effect of possible confounders such as sex and ethnicity upon the genetic effect to be estimated. We will show examples of how a meta-analysis can inflate the false negative rates of genetic association studies or it can bias estimates of the association between a genetic variant and extreme longevity.

The Neurobiology and Age-Related Prevalence of the ε4 Allele of Apolipoprotein E in Alzheimer's Disease Cohorts

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterised by amyloid beta (Aβ) plaques and tau neurofibrillary tangles in the brain. Human apolipoprotein E (ApoE) is a lipid transport protein coded by the polymorphic APOE gene, with three major alleles: ε2, ε3 and ε4. After age, the ε4 allele is the greatest risk factor for developing sporadic AD, conferring an increased risk of 3-4 and 8-12 times for one or two copies of the allele, respectively. This risk is reported to vary by demographic factors including sex, ethnicity and geography. In order to understand the risk of ApoE ε4 in relation to age, the primary risk factor for developing AD, we need to understand how the prevalence of APOE genotypes changes with age. Here, we present the first data on age-related prevalence of APOE ε4 in AD in three AD cohorts in Australia and the USA. There is a significant association between age and ε4 prevalence, particularly for ε4 homozygotes, such that as age increases the prevalence of ε4 decreases. Further studies on a random, population-based sample of the population are needed to provide more generalizable data, particularly in the >90-year-old age group.

Age, APOE and sex: Triad of risk of Alzheimer's disease

Age, apolipoprotein E ε4 (APOE) and chromosomal sex are well-established risk factors for late-onset Alzheimer's disease (LOAD; AD). Over 60% of persons with AD harbor at least one APOE-ε4 allele. The sex-based prevalence of AD is well documented with over 60% of persons with AD being female. Evidence indicates that the APOE-ε4 risk for AD is greater in women than men, which is particularly evident in heterozygous women carrying one APOE-ε4 allele. Paradoxically, men homozygous for APOE-ε4 are reported to be at greater risk for mild cognitive impairment and AD. Herein, we discuss the complex interplay between the three greatest risk factors for Alzheimer's disease, age, APOE-ε4 genotype and chromosomal sex. We propose that the convergence of these three risk factors, and specifically the bioenergetic aging perimenopause to menopause transition unique to the female, creates a risk profile for AD unique to the female. Further, we discuss the specific risk of the APOE-ε4 positive male which appears to emerge early in the aging process. Evidence for impact of the triad of AD risk factors is most evident in the temporal trajectory of AD progression and burden of pathology in relation to APOE genotype, age and sex. Collectively, the data indicate complex interactions between age, APOE genotype and gender that belies a one size fits all approach and argues for a precision medicine approach that integrates across the three main risk factors for Alzheimer's disease.

The genetics of exceptional longevity: Insights from centenarians

As the world population ages, so the prevalence increases of individuals aged 100 years or more, known as centenarians. Reaching this age has been described as exceptional longevity (EL) and is attributed to both genetic and environmental factors. Many genetic variations known to affect life expectancy exist in centenarians. This review of studies conducted on centenarians and supercentenarians (older than 110 years) updates knowledge of the impacts on longevity of the twenty most widely investigated single nucleotide polymorphisms (SNPs).

The ApoE gene is related with exceptional longevity: a systematic review and meta-analysis

The objective of this meta-analysis was to determine the association of the apolipoprotein E (ApoE) gene with exceptional longevity (EL) (i.e., reaching 100+ years) by identifying possible unequal distribution of alleles/genotypes in the common variants ε2, ε3, and ε4 among centenarians and younger population. The association of ApoE with EL was analyzed in a total of 2776 centenarians (cases) and 11,941 younger controls (from 13 case-control studies) using the chi-squared test with the Yates correction. We conducted combined and separate analyses for all ethnic groups studied in the literature (Caucasian and Asian). The main result for all ethnic groups combined was that the likelihood of reaching EL was negatively associated with ε4 allele carriage [pooled odds ratio (OR)=0.43; 95% confidence interval (CI) 0.36, 0.50; p<0.001] and with ε4/ε4 (OR=0.18; 95% CI 0.08, 0.39; p<0.001), ε3/ε4 (OR=0.44; 95% CI 0.37, 0.53; p<0.001) and ε2/ε4 genotypes (OR=0.48; 95% CI 0.31, 0.74; p<0.001). In contrast, the ε2/ε3 genotype was positively associated with EL (OR=1.35; 95% CI 1.06, 1.72; p=0.017). When compared with the ε3 allele, the ε2 allele was not associated with increased odds of EL (OR=1.08; 95% CI 0.77, 1.50, p=0.660). The present meta-analysis confirms that, besides its previously documented influence on Alzheimer's and cardiovascular disease risk, the ApoE gene is associated with the likelihood of reaching EL.

ApoE gene and exceptional longevity: Insights from three independent cohorts

The ApoE gene is associated with the risk of Alzheimer or cardiovascular disease but its influence on exceptional longevity (EL) is uncertain. Our primary purpose was to determine, using a case-control design, if the ApoE gene is associated with EL. We compared ApoE allele/genotype frequencies among the following cohorts: cases (centenarians, most with 1+ major disease condition; n=163, 100-111years) and healthy controls (n=1039, 20-85years) from Spain; disease-free cases (centenarians; n=79, 100-104years) and healthy controls (n=597, age 27-81years) from Italy; and cases (centenarians and semi-supercentenarians, most with 1+ major disease condition; n=729, 100-116years) and healthy controls (n=498, 23-59years) from Japan. Our main findings were twofold. First, the ε4-allele was negatively associated with EL in the three cohorts, with the following odds ratio (OR) values (adjusted by sex) having been found: 0.55 (95% confidence interval (CI): 0.33, 0.94), P=0.030 (Spain); 0.41 (95%CI: 0.18, 0.99), P=0.05 (Italy); and 0.35 (95%CI: 0.26, 0.57), P<0.001 (Japan). Second, although no association was found in the Spanish cohort (OR=1.42 (95%CI: 0.89, 2.26), P=0.145), the ε2-allele was positively associated with EL in the Italian (OR=2.14 (95%CI: 1.18, 3.45), P=0.01) and Japanese subjects (OR=1.81 (95%CI: 1.25, 2.63), P=0.002). Notwithstanding the limitations of case-control designs, our data suggest that the ApoE might be a candidate to influence EL. The ε4-allele appears to decrease the likelihood of reaching EL among individuals of different ethnic/geographic origins. An additional, novel finding of our study was that the ε2-allele might favor EL, at least in the Italian and Japanese cohorts.

The forgotten APOE allele: a review of the evidence and suggested mechanisms for the protective effect of APOE ɛ2

Ongoing efforts to improve survival, and enhance quality of life have led biomedical research to focus on disease and the mechanisms that increase risk for disease. The other side of that coin may be as important, i.e. examining the protective factors that allow some individuals to enjoy long, healthy lives. One of the best examples of a gene that positively influences cognitive health is the apolipoprotein (APOE) ɛ2 allele. The APOE ɛ4 allele is a well-established risk factor for Alzheimer's disease (AD) and has thus dominated the APOE literature, with the putative protective role of ɛ2 receiving little attention. This review describes the effects of APOE ɛ2 on the structure and function of the brain. With a focus on neurodegeneration, we discuss evidence for APOE ɛ2's protective effects, explore some key mechanisms through which this protection may be conferred, and address a few inconsistencies in the literature. Understanding the mechanisms that underlie the association between APOE ɛ2, cognition and longevity may provide new targets for research on promoting life-long health.

Apolipoprotein E genotype, dementia, and mortality in the oldest old: the 90+ Study

BACKGROUND

Although the apolipoprotein E (APOE) ε4 allele is a major genetic risk factor for Alzheimer's disease (AD), it is not clear whether this relationship persists among the oldest old. Several European studies suggest that the effect of the APOE ε4 allele on dementia and mortality disappears in very old age. We describe the APOE allele and genotype frequencies and examine whether the presence of the APOE ε4 or APOE ε2 alleles is related to prevalent dementia, incident dementia, and mortality in a population-based cohort of oldest-old participants in the United States.

METHODS

We studied 904 participants aged 90 years and older from The 90+ Study. Eight hundred two (89%) participants were genotyped and included in the prevalent dementia and mortality analyses. The 520 initially nondemented participants were included in the incident dementia analyses and were evaluated for dementia every 6 months.

RESULTS

The APOE ε4 allele was significantly associated with prevalent dementia (odds ratio = 2.06) and AD (odds ratio = 2.37) in women but not in men. The APOE ε2 allele was not related to prevalent dementia in either sex. After an average follow-up of 2.4 years, 188 incident dementia cases were identified. Neither the APOE ε4 nor the APOE ε2 allele was related to incident dementia or AD. Five hundred ten (64%) participants died after an average follow-up of 2.3 years, and their mortality was not related to the presence of either the APOE ε2 or APOE ε4 allele.

CONCLUSIONS

Our findings suggest that the associations between APOE ε4, dementia, and mortality are age dependent, and that APOE ε4 no longer plays a role in dementia and mortality at very old ages.

Apolipoprotein E and familial longevity

Exceptional longevity is associated with substantial heritability. The ε4 allele in apolipoprotein E and the linked G allele in rs2075650 of TOMM40 have been associated with increased mortality and the ε2 allele with decreased mortality, although inconsistently. Offspring from long-lived families and spouse controls were recruited at 3 sites in the United States and Denmark. We used generalized estimating equations to compare the likelihood of carrying risk alleles in offspring (n = 2307) and spouse controls (n = 764), adjusting for age, sex, level of education, and family membership. The likelihood of carrying an APOE ε4 allele or a G allele in rs2075650 was lower (odds ratio [OR], 0.75; p = 0.005 and OR, 0.70; p = 0.002) and the likelihood of carrying an APOE ε2 allele was higher (OR, 1.5; p = 0.007) among family members in the offspring generation than among their spouse controls. Our findings support the hypothesis that both reduction in the frequency of the ε4 allele and increase in the frequency of the ε2 allele contribute to longevity.

Ideal lipid profile and genes for an extended life span

PURPOSE OF REVIEW

The world population is aging and a rapid increase is being seen in the very elderly (aged >80 years). Cholesterol levels in general rise with age and high cholesterol has been associated with extreme longevity. The relationship between lipids and cardiovascular events in the extreme elderly is unclear.

RECENT FINDINGS

A number of genetic factors associated with lipid metabolism have also been described as having potential antiaging roles, including the genes encoding lipoprotein-associated factors - apolipoprotein E and cholesterol ester transfer protein; adipose tissue metabolism - adiponectin, leptin, glycaemia; and blood pressure - angiotensinogen. Clinical trials of lipid-lowering therapies have recruited subgroups of moderately elderly patients, but only the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER) trial specifically recruited an elderly population. There is no direct equivalent of the Hypertension in the Very Elderly trial (HYVET) study of antihypertensive patients in the extreme elderly. No heterogeneity has been seen with the effects of statin therapy in the elderly compared with younger age groups on classical cardiovascular endpoints of coronary heart disease and stroke.

SUMMARY

The optimal cholesterol target, long-term tolerability and the specific effects of statins on other vascular-associated diseases of aging, for example arterial aneurysms, microvascular renal and cerebral disease (dementias), remain to be determined.

RNA surveillance-an emerging role for RNA regulatory networks in aging

In this review, we describe recent advances in the field of RNA regulatory biology and relate these advances to aging science. We introduce a new term, RNA surveillance, an RNA regulatory process that is conserved in metazoans, and describe how RNA surveillance represents molecular cross-talk between two emerging RNA regulatory systems-RNA interference and RNA editing. We discuss how RNA surveillance mechanisms influence mRNA and microRNA expression and activity during lifespan. Additionally, we summarize recent data from our own laboratory linking the RNA editor, ADAR, with exceptional longevity in humans and lifespan in Caenorhabditis elegans. We present data showing that transcriptional knockdown of RNA interference restores lifespan losses in the context of RNA editing defects, further suggesting that interaction between these two systems influences lifespan. Finally, we discuss the implications of RNA surveillance for sarcopenia and muscle maintenance, as frailty is a universal feature of aging. We end with a discussion of RNA surveillance as a robust regulatory system that can change in response to environmental stressors and represents a novel axis in aging science.

The role of genetic variants in human longevity

Human longevity is a complex phenotype with a strong genetic predisposition. Increasing evidence has revealed the genetic antecedents of human longevity. This article aims to review the data of various case/control association studies that examine the difference in genetic polymorphisms between long-lived people and younger subjects across different human populations. There are more than 100 candidate genes potentially involved in human longevity; this article particularly focuses on genes of the insulin/IGF-1 pathway, FOXO3A, FOXO1A, lipoprotein metabolism (e.g., APOE and PON1), and cell-cycle regulators (e.g., TP53 and P21). Since the confirmed genetic components for human longevity are few to date, further precise assessment of the genetic contributions is required. Gaining a better understanding of the contribution of genetics to human longevity may assist in the design of improved treatment methods for age-related diseases, delay the aging process, and, ultimately, prolong the human lifespan.

Total and cause-specific mortality in the cardiovascular health study

BACKGROUND

Few cohort studies have adequate numbers of carefully reviewed deaths to allow an analysis of unique and shared risk factors for cause-specific mortality. Shared risk factors could be targeted for prevention of premature death and the study of longevity.

METHODS

A total of 5,888 community-dwelling persons aged 65 years or older living in four communities in the United States participated in the Cardiovascular Health Study cohort. Participants were initially recruited from 1989 to 1990; an additional 687 black participants were recruited in 1992-1993. The average length of follow-up was 16 years. Total and cause-specific mortality, including cardiovascular disease, stroke, cancer, dementia, pulmonary disease, infection, and other cause, were examined as outcomes. Variables previously associated with total mortality were examined for each cause of death using Cox proportional hazard models.

RESULTS

Multiple risk factors were related to total mortality. When examining specific causes, many factors were related to cardiovascular death, whereas fewer were related to other causes. For most causes, risk factors were specific for that cause. For example, apolipoprotein E epsilon4 was strongly associated for dementia death and forced vital capacity with pulmonary death. Age, male sex, markers of inflammation, and cognitive function were related to multiple causes of death.

CONCLUSIONS

In these older adults, associations of risk factors with a given cause of death were related to specific deficits in that same organ system. Inflammation may represent a common pathway to all causes of death.

Genetic variation in healthy oldest-old

Individuals who live to 85 and beyond without developing major age-related diseases may achieve this, in part, by lacking disease susceptibility factors, or by possessing resistance factors that enhance their ability to avoid disease and prolong lifespan. Healthy aging is a complex phenotype likely to be affected by both genetic and environmental factors. We sequenced 24 candidate healthy aging genes in DNA samples from 47 healthy individuals aged eighty-five years or older (the 'oldest-old'), to characterize genetic variation that is present in this exceptional group. These healthy seniors were never diagnosed with cancer, cardiovascular disease, pulmonary disease, diabetes, or Alzheimer disease. We re-sequenced all exons, intron-exon boundaries and selected conserved non-coding sequences of candidate genes involved in aging-related processes, including dietary restriction (PPARG, PPARGC1A, SIRT1, SIRT3, UCP2, UCP3), metabolism (IGF1R, APOB, SCD), autophagy (BECN1, FRAP1), stem cell activation (NOTCH1, DLL1), tumor suppression (TP53, CDKN2A, ING1), DNA methylation (TRDMT1, DNMT3A, DNMT3B) Progeria syndromes (LMNA, ZMPSTE24, KL) and stress response (CRYAB, HSPB2). We detected 935 variants, including 848 single nucleotide polymorphisms (SNPs) and 87 insertion or deletions; 41% (385) were not recorded in dbSNP. This study is the first to present a comprehensive analysis of genetic variation in aging-related candidate genes in healthy oldest-old. These variants and especially our novel polymorphisms are valuable resources to test for genetic association in models of disease susceptibility or resistance. In addition, we propose an innovative tagSNP selection strategy that combines variants identified through gene re-sequencing- and HapMap-derived SNPs.

Centenarians--a useful model for healthy aging? A 29-year follow-up of hospitalizations among 40,000 Danes born in 1905

Centenarians surpass the current human life expectancy with about 20-25 years. However, whether centenarians represent healthy aging still remains an open question. Previous studies have been hampered by a number of methodological shortcomings such as a cross-sectional design and lack of an appropriate control group. In a longitudinal population-based cohort, it was examined whether the centenarian phenotype may be a useful model for healthy aging. The study was based on a complete follow up of 39,945 individuals alive in the Danish 1905 birth cohort on January 1, 1977 identified through the Danish Civil Registration System (DCRS). Data from the Danish Demographic Database and The Danish National Patient Register (in existence since 1977) were used. The 1905 cohort was followed up from 1977 through 2004 with respect to hospitalizations and number of hospital days. Survival status was available until December 2006. Danish centenarians from the 1905 cohort were hospitalized substantially less than their shorter-lived contemporaries at the same point in time during the years 1977 through 2004. For example, at age 71-74, the proportion of nonhospitalized centenarians was 80.5% compared with 68.4% among individuals who died in their early 80s. This trend was evident in both sexes. As a result of their lower hospitalization rates and length of stay in hospital compared with their contemporaries, who died at younger ages, Danish centenarians represent healthy agers. Centenarians constitute a useful study population in the search for fixed traits associated with exceptional longevity, such as genotype.

Genetic epidemiology in aging research

Over the last two decades, aging research has expanded to include not only age-related disease models, and conversely, longevity and disease-free models, but also focuses on biological mechanisms related to the aging process. By viewing aging on multiple research frontiers, we are rapidly expanding knowledge as a whole and mapping connections between biological processes and particular age-related diseases that emerge. This is perhaps most true in the field of genetics, where variation across individuals has improved our understanding of aging mechanisms, etiology of age-related disease, and prediction of therapeutic responses. A close partnership between gerontologists, epidemiologists, and geneticists is needed to take full advantage of emerging genome information and technology and bring about a new age for biological aging research. Here we review current genetic findings for aging across both disease-specific and aging process domains. We then highlight the limitations of most work to date in terms of study design, genomic information, and trait modeling and focus on emerging technology and future directions that can partner genetic epidemiology and aging research fields to best take advantage of the rapid discoveries in each.

Variation in NPC1, the gene encoding Niemann-Pick C1, a protein involved in intracellular cholesterol transport, is associated with Alzheimer disease and/or aging in the Polish population

There is abundant evidence that cholesterol metabolism, especially as mediated by the intercellular transporter APOE, is involved in the pathogenesis of sporadic, late-onset Alzheimer disease (SLAD). Identification of other genes involved in SLAD pathogenesis has been hampered since gene association studies, whether individual or genome-wide, experience difficulty in finding appropriate controls in as much as 25% or more of normal adults will develop SLAD. Using 152 centenarians as additional controls and 120 "regular", 65-75-year-old controls, we show an association of genetic variation in NPC1 with SLAD and/or aging. In this preliminary study, we find gradients of two non-synonymous SNP's allele frequencies in NPC1 from centenarians through normal controls to SLAD in this non-stratified Polish population. An intervening intronic SNP is not in Hardy-Weinberg equilibria and differs between centenarians and controls/SLAD. Haplotypes frequencies determined by fastPHASE were somewhat different, and the predicted genotype frequencies were very different between the three groups. These findings can also be interpreted as indicating a role for NPC1 in aging, a role also suggested by NPC1's role in Dauer formation (hibernation, a longevity state) in Caenorhabditis elegans.

Longevity genes

Ha elfogadjuk, hogy az öregedés biológiailag szabályozott életfolyamat, akkor továbbgondolva adódik a feltételezés, hogy biztosan van genetikai kódja. Márpedig ha van kódja, akkor a humán genom ismeretében ez megfejthető. Ha megfejthető, akkor manipulálható is. Ha azonban ezen mesterkedünk, akkor azt tegyük úgy, hogy a megnövelt élettartam a fizikai és szellemi jóllét csúcsán elérhető állapotot tartósítsa. Tehát ne csak az élethosszt növeljük, de egyúttal a betegségekkel szembeni ellenállást is. Szerte a világon sok kutatóintézet foglalkozik ma már ezzel a témával, és lázasan fáradoznak a megvalósításon. Az összefoglaló a feltárt ismeretanyagból ad ízelítőt.

Lipoproteins, vascular-related genetic factors, and human longevity

The relationships among lipoprotein metabolism, genetic vascular factors, vascular disease, and Alzheimer's disease suggest that the examination of centenarian populations in relation to certain genes or lipoprotein metabolism provide insights into human longevity. The findings on the higher frequency of the apolipoprotein E epsilon4 allele in middle-aged subjects than in centenarians were substantially confirmed. On the contrary, recent findings did not confirm previous data on increased prevalence of the high-risk angiotensin I converting enzyme D allele in French centenarians. The variability in the strength of association between angiotensin I converting enzyme polymorphism and longevity could be related to regional differences in angiotensin I converting enzyme D allele frequency in Europe recently showed, as also recently reported for apolipoprotein Eepsilon2 and epsilon4 allele in centenarians. Indeed some studies of lipoprotein profiles in centenarians have also had contradictory outcomes, with evidence of lower serum levels of high-density lipoprotein cholesterol, with higher high-density lipoprotein 2 cholesterol subfraction, larger high-density lipoprotein and low-density lipoprotein particle sizes, and higher lipoprotein(a) concentration in centenarians, which is apparently disadvantageous for human longevity. Elevated lipoprotein(a) serum levels, increasing the risk for cerebrovascular disease, may play a role in determining clinical Alzheimer's disease, but lipoprotein(a) elevation in centenarians, in the absence of other coronary artery disease risk factors, appears as a positive survival factor. In different populations, there are significant trends in the reduction of serum apolipoprotein E levels from apolipoprotein E epsilon2- to epsilon4-carriers and significant differences in serum apolipoprotein E levels with respect to age in epsilon4-carriers but only after adjustment for high-density lipoprotein cholesterol. While further studies are needed to confirm the possible role of apolipoprotein E concentration as putative longevity factor this paper provides an overview of many of the investigated vascular factors with respect to longevity.

Exact sample size needed to detect dependence in 2 x 2 x 2 tables

In the Georgia Centenarian Study (Poon et al., Exceptional Longevity, 2006), centenarian cases and young controls are classified according to three categories (age, ethnic origin, and single nucleotide polymorphisms [SNPs] of candidate longevity genes), where each factor has two possible levels. Here we provide methodologies to determine the minimum sample size needed to detect dependence in 2 x 2 x 2 tables based on Fisher's exact test evaluated exactly or by Markov chain Monte Carlo (MCMC), assuming only the case total L and the control total N are known. While our MCMC method uses serial computing, parallel computing techniques are employed to solve the exact sample size problem. These tools will allow researchers to design efficient sampling strategies and to select informative SNPs. We apply our tools to 2 x 2 x 2 tables obtained from a pilot study of the Georgia Centenarians Study, and the sample size results provided important information for the subsequent major study. A comparison between the results of an exact method and those of a MCMC method showed that the MCMC method studied needed much less computation time on average (10.16 times faster on average for situations examined with S.E. = 2.60), but its sample size results were only valid as a rule for larger sample sizes (in the hundreds).

Apolipoprotein E polymorphism, age and coronary heart disease

Plasma concentrations of lipids, lipoproteins, and apolipoproteins (apo) are established risk factors for coronary heart disease (CHD). The knowledge of lipid profile may predict the potential victims of cardiovascular disease before its initiation and progression and offer the opportunity for primary prevention. The most common apo E polymorphism has been found to influence blood lipid concentrations and its correlation with CHD has been extensively investigated in the last decade. At younger ages, death from CHD is influenced by genetic factors, while the genetic effect decreases at older ages where environmental factors may play a more prominent role. If apo E polymorphism is an important genetic factor in the pathogenesis of atherosclerosis, it could affect the age of CHD onset. This review analyses the influence of apo E polymorphism on blood lipids and CHD in respect to age.

Differences in the Association Between Apolipoprotein E Genotype and Mortality Across Populations

BACKGROUND

The gene for apolipoprotein-E (APOE) has three common alleles (epsilon2, epsilon3, and epsilon4) that have been shown to be associated with differences in the risk of death in persons older than 60 years in European populations. However, previous research suggests that they may not be associated with mortality in African Americans, and the evidence in Asians is mixed. It is now possible to examine the effects of these genotypes on mortality in African American, Chinese, Japanese, and Korean populations.

METHODS

The analysis is based on two types of published data: genotype by age and mortality by genotype. Demographic synthesis uses a multistate model to combine data from these case-control and cohort studies to provide maximum likelihood estimates of the relative risks of death.

RESULTS

In general, the APOE epsilon2 allele is associated with 5%-10% lower mortality than the epsilon3/3 genotype. The epsilon4/4 allele is generally associated with a moderately high relative risk of death. The epsilon3/4 genotype is associated with 22% excess risk in Europeans and U.S. whites and with about 35% in Chinese. However, there is no evidence of excess risk with epsilon3/4 among African Americans and little excess risk among Japanese and Koreans. The relationship between genotype and mortality is consistent within these ethnic groups. For example, the estimates of R(3/4) for Japanese in Japan and Hawaii are both low, and the estimates for Chinese in Taiwan and Shanghai are relatively high.

CONCLUSIONS

. The relationship between APOE genotype and mortality differs across population groups but shows little evidence of variation within groups.

Genetic variation and human aging: progress and prospects

The genetics of aging has seen extraordinary progress over the last few decades, with animal models suggesting key roles for a number of metabolic pathways. However, humans outlive laboratory models many times over, and only evidence from humans can ultimately identify the drivers of human aging. In this article we thematically review progress in identifying human genetic variants associated with longevity. We also look at the bigger picture of progress in identifying genetic associates of disease and functioning and healthy aging in older people. Although much of the existing evidence is fragmentary, recent exciting findings and robust methods are taking the field rapidly forward.

Hemostasis and aging

Many changes in the vasculature, hemostasis and endothelium, including alterations of platelets, coagulation and fibrinolytic factors, occur during aging. While the increasing hypercoagulability observed with aging may account for the higher incidence of thrombotic cardiovascular disorders in the elderly, the lack of genetic protective factors against thrombosis in healthy centenarians suggests that little is yet known about the age-associated changes of hemostasis. The complex inter-relationships between inherited and acquired factors influencing the hemostatic system during aging are discussed in this review.

Sex differences in the association of apolipoprotein E and angiotensin-converting enzyme gene polymorphisms with healthy aging and longevity: a population-based study from Southern Italy

We investigated the association of sex and age with the occurrence of apolipoprotein E (apoE) and angiotensin-converting enzyme (ACE) genotypes in healthy aging and longevity in 1344 healthy individuals and 64 centenarians. As compared to participants younger than 60 years, a significant higher frequency of the apoE/epsilon2 was observed in men aged 60-90 years (p <.001) and in centenarians (p <.001). Logistic regression analysis confirmed this outcome in both participants aged 60-90 years (odds ratio [OR] = 1.897; 95% confidence interval [CI], 1.227-2.931) and centenarians (OR = 3.263; 95% CI, 1.860-5.722). A further significant association of ACE/D allele and age was observed in centenarians (OR = 2.135; 95% CI, 1.253-3.636). Heterosis was also observed at the ACE locus. No relationship between apoE and ACE polymorphism was found. These findings suggest a role of sex in the association of apoE and ACE gene polymorphisms with healthy aging and longevity.

Is aging part of Alzheimer's disease, or is Alzheimer's disease part of aging?

For 70 years after Alois Alzheimer described a disorder of tangle-and-plaque dementia, Alzheimer's disease was a condition of the relatively young. Definitions of Alzheimer's disease (AD) have, however, changed over the past 30 years and under the revised view AD has truly become an age-related disease. Most now diagnosed with AD are elderly and would not have been diagnosed with AD as originally conceived. Accordingly, younger patients that qualify for a diagnosis of AD under both original and current Alzheimer's disease constructs now represent an exceptionally small percentage of the diagnosed population. The question of whether pathogenesis of the "early" and "late" onset cases is similar enough to qualify as a single disease was previously raised although not conclusively settled. Interestingly, debate on this issue has not kept pace with advancing knowledge about the molecular, biochemical and clinical underpinnings of tangle-and-plaque dementias. Since the question of whether both forms of AD share a common pathogenesis could profoundly impact diagnostic and treatment development efforts, it seems worthwhile to revisit this debate.

Apolipoprotein E Genotypes: Relationship to Cognitive Functioning, Cognitive Decline, and Survival in Nonagenarians

OBJECTIVES

To evaluate the extent to which relationships between apolipoprotein E, cognitive functioning, and survival in people aged 60 to 80 persist into advanced old age.

DESIGN

Examine the effect of apolipoprotein E genotypes on baseline cognitive functioning, cognitive decline over 5 years, and survival in a cohort of 1,551 nonagenarians.

SETTING

The Danish 1905 birth cohort.

PARTICIPANTS

One thousand five hundred fifty-one nonagenarians from the Danish 1905 birth cohort.

MEASUREMENTS

Cognitive functioning was assessed using the Mini-Mental State Examination (MMSE) and five brief cognitive tests (cognitive composite).

RESULTS

The subjects were stratified into four groups by occurrence of a protective (epsilon2) or a risk (epsilon4) apo E allele (epsilon22 and epsilon23, epsilon33, epsilon24 and epsilon34, epsilon44). At intake, the mean scores for the three genotype groups were 22.1, 21.8, 21.4, and 21.0 for MMSE and 0.10, 0.07, -0.02, and 0.30 for the cognitive composite, respectively. Growth-curve analyses showed that, although individuals carrying at least one epsilon4 allele had slightly lower MMSE scores and declined slightly more rapidly over time, this effect was not statistically significant and was not apparent in scores on the cognitive composite. In subjects whose functioning was relatively well preserved (those still living and able to participate in the assessment, and whose cognitive functioning had declined less than 4 points on the MMSE), epsilon4 frequencies tended to decline at subsequent waves (P=.03, chi-square test for trend), but epsilon4 had no significant survival disadvantage (hazard ratio=1.11 (95% confidence interval=0.99-1.25; P=.07).

CONCLUSION

Apo E genotype has a small effect on the probability of remaining a well-functioning nonagenarian but no separately detectable effect on cognitive functioning, cognitive decline, or survival.

Apolipoprotein E genotype is related to plasma levels of C-reactive protein and lipids and to longevity in nonagenarians

OBJECTIVE

Apolipoprotein E (APOE) genotype is a regulator of hepatic lipoprotein metabolisms and has been linked with longevity. The relationship between APOE genotype and plasma C-reactive protein (CRP), which is produced by the liver during inflammation, has not been studied in nonagenarians. The aim of the present study was to establish whether APOE genotype is related to plasma concentrations of CRP and lipids, or longevity among nonagenarians.

DESIGN AND PATIENTS

This cross-sectional study consisted of 291 Finnish nonagenarians and three previously described and genotyped control populations from the same area (i.e. newborns, 40-year-olds, and 70-year-olds).

RESULTS

In all nonagenarians and especially in women (P= 0.038), CRP level decreased linearly in the genotype order of epsilon2/2, epsilon2/3, epsilon3/3, epsilon2/4, epsilon3/4 and epsilon4/4. Total (P= 0.009) and low-density lipoprotein (LDL) cholesterol (P = 0.076) levels, in turn, were increased in the epsilon4 allele carriers. In newborns, the epsilon4 frequency was 0.192, in 40-year-olds 0.181, in 70-year-olds 0.179 and in nonagenarians 0.095 (P < 0.0001). The decrease in the epsilon4 allele frequency in the elderly was more clearly seen in women than in men.

CONCLUSIONS

APOEepsilon4 allele seems to be associated with decreased inflammatory response as measured by CRP among nonagenarians. This finding may partly explain why some epsilon4 allele carriers can reach very old age despite increased risk of hypercholesterolaemia.

Apo-E Genotypes and Cardiovascular Diseases: A Sensitivity Study Using Cross-validatory Criteria

The Apolipoprotein-E (Apo-E) gene, a gene that produces proteins which help to regulate lipid levels in the bloodstream, is of interest in the study of cardiovascular diseases. An approach to making inferences about the genetic effects of the Apo-E gene has been developed by Glickman and Gagnon (2002). The framework describes the role of genetic and risk factors on the onset ages of multiple diseases, and accounts for the possibility that an individual was censored for reasons related to the diseases of interest. The framework also allows for missing genetic information, so that subjects censored prior to genetic sampling, and therefore missing such information, may still be included in the analysis. We apply an extension to this framework to the original cohort of the Framingham Heart Study for measuring the effects of different Apo-E genotypes on the onset age of various cardiovascular disease events. In particular, we compare the fit of univariate versus multivariate onset age components to the model, whether to incorporate health covariates measured at baseline or at a point later in the study, and whether to assume a heritability model for Apo-E genotype frequencies. The results of the best fitting model are presented.

Mismatch repair system and aging: microsatellite instability in peripheral blood cells from differently aged participants

Age-related alterations of DNA repair could be involved in the accumulation of genetic damage with age. Few data suggest a possible alteration with age of the mismatch repair system, evidenced by the acquisition of microsatellite instability. We aimed to point out a possible implication of this repair system in the accumulation of genetic damage with age. Peripheral blood cell DNA from 226 participants, 110 young (25-35 years), 58 old (85-97 years), and 58 centenarian was analyzed at five polymorphic microsatellite loci (CD4, p53, VWA31, TPOX, and FES/FPS) to point out age-related instabilities or modifications in allele frequencies. FES/FPS microsatellite was the most instable, showing both the appearance of trizygosis in DNA from old participants and differences in allele patterns among age groups, thus indicating an association between increased microsatellite instability and aging, one of the possible causes of which being an impairment of mismatch repair system capacity with age.

Preservation of cognitive and functional ability as markers of longevity

Longevity is a complex biological process for which the phenotypes have not been established. Preservation of cognitive and physical function may be important and preservation of these functions is, in part, inherited. We investigated the relation between rate of change in cognitive and functional abilities in probands and risk of death in their siblings. Probands were classified as showing no decline, slow, medium, or rapid rate of decline, based on the slope of change in cognitive and physical/functional factors over three or more assessments. Siblings of probands who did not decline on measures of memory, visuospatial/cognitive function or ADL skills were approximately half as likely to die as siblings of probands who had the most rapid decline. The reduction in risk of death in siblings of probands who did not decline in was primarily observed among siblings of probands who were older than 75 years, suggesting that genetic influences on life span may be greater at older ages. There was no association between probands' rate of change in language, IADL skills, upper or lower extremity mobility and risk of death in siblings. The results of the present study identify phenotypes associated with preserved cognitive and functional abilities which may serve as markers for longevity.

Interleukin 6 −174 G/C promoter gene polymorphism in centenarians: no evidence of association with human longevity or interaction with apolipoprotein E alleles

The C allele at position -174 in the promoter of the interleukin 6 (IL-6) gene has been associated with reduced gene expression and reduced plasma levels of IL-6. Given that IL-6 tracks with functional disability and age-related diseases, there may be attrition or reduction in the frequency of the homozygous subjects, who produce higher IL-6 serum levels, in older survivors in a population. In fact, a marked reduction of the IL-6*G/*G genotype was recently demonstrated in male though not female Italian centenarians compared with younger age groups. First aim of the present study was to investigate whether there was evidence of an association among IL-6 -174 G/C promoter polymorphism and extreme longevity in a population of 81 centenarians compared with a control group of 122 middle-aged healthy subjects (mean age: 51+/-18 SD; range: 19-73 years), from Apulia (Southern Italy). Secondly, we also tested possible interaction of apolipoprotein E (APOE) alleles with the IL-6 -174 G/C promoter polymorphism in view of our recent findings for reduced APOE epsilon4 allele in centenarians. No differences have been found in the IL-6 -174 G/C promoter allele and genotype frequencies between centenarians and controls nor was there any observed interaction with APOE alleles that are also reputed to be linked to longevity. Regional genetic differences in conjunction with differing environmental factors may explain in part previous results suggesting a role of this polymorphism in longevity.

Association of apolipoprotein E genotypes, blood pressure, blood lipids and ECG abnormalities in a general population aged 85+

BACKGROUND

Several studies have linked apolipoprotein E (ApoE) epsilon4 allele with elevated cholesterol and blood pressure levels. Data on the association of APOE genotypes with blood pressure, lipids, atrial fibrillation and ECG abnormalities in individuals aged 85 years and over is sparse.

METHODS

This cross sectional study consisted of all residents of the city of Vantaa (N = 601) aged 85 years or over of whom 505 participated in the study. Blood pressure was measured by using mercury sphygmomanometer. 12-Lead ECG, short ambulatory ECG, or both were taken from all study subjects to diagnose atrial fibrillation (AF). Ambulatory ECG was carried out home or in the institute. APOE genotyping was performed using a combination of the polymerase chain reaction (PCR) and solid-phase minisequencing technique. Statistical analysis was made by using Kruskall-Wallis-test (continuous data) and chi2-test (rates and proportions).

RESULTS

In these very elderly individuals, APOE 4 allele was significantly associated with elevated cholesterol and low-density lipoprotein (LDL) levels. Blood pressure or cardiac arrhythmias did not differ between APOE genotypes.

CONCLUSIONS

These observations suggest that the important role of APOE genotype still influences cardiovascular risk profile even among the very elderly people.

Vascular genetic factors and human longevity

Complex inter-relationships between age-associated illnesses, such as vascular disease and Alzheimer's disease (AD), suggest that biological and genetic pathways may be worthy of examination in centenarian populations to provide insights into human longevity. This is also borne out by the involvement of lipoprotein metabolism and a number of vascular genetic risk factors. Repeated findings of a higher frequency of the apolipoprotein E (APOE) epsilon4 allele in middle-aged subjects compared with centenarians were reported. Furthermore, we have also shown how in different populations there is a significant trend in reduction of serum APOE levels from APOE epsilon2- to epsilon4-carrier as well as significant differences in serum APOE levels respect to age in epsilon4-carriers but only after adjustment for HDL cholesterol. In contrast, findings of increased prevalence of the angiotensin I converting enzyme 1 (ACE1) D allele in French centenarians have not been replicated, suggesting the possibility that regional differences may occur in ACE1(*)D frequency within Europe in centenarians, as has been recently reported for APOE epsilon2 and epsilon4 alleles. A number of studies have examined the potential role in longevity of other genes involved in vascular risk, haemostasis, and blood pressure regulation [methyltetrahydrofolatereductase (MTHFR), apolipoprotein A1 (APOA-I), apolipoprotein C3 (APOC-III), apolipoprotein A4 (APOA-IV), paraoxonase 1 (PON1), plasminogen activator inhibitor type I (PAI-1)], with contrasting results. While further studies are needed to confirm the possible role of APOE concentration as putative longevity factor, this paper provides an overview of genetic vascular factors potentially involved in human longevity.

The normal population distribution of PRNP codon 129 polymorphism

OBJECTIVES

The common prion protein gene (PRNP) codon 129 polymorphism modifies the susceptibility to and the phenotype of prion diseases. However, no truly representative normal population-based data, or data stratified according to age or gender are available on the distribution of this polymorphism.

MATERIAL AND METHODS

Allelic variation of codon 129 in three Finnish populations representing different age groups, and among Finnish, British and Irish blood donors were examined.

RESULTS

The PRNP codon 129 genotype distribution in the total Finnish sample was 49% for methionine-methionine (MM), 42% for methionine-valine (MV) and 9% for valine-valine (VV), for the UK blood donors 42% for MM, 47% for MV and 11% for VV, and for the Irish blood donors 34% for MM, 56% for MV, and 10% for VV.

CONCLUSIONS

The genotype frequencies were almost identical in all three Finnish populations of different ages, with no gender differences, and did not differ from corresponding figures for the Finnish blood donors. However, the PRNP codon 129 genotype distribution in Finland differed significantly from that of the British and the Irish blood donors and the previously published blood donor data on other Western Europeans and Americans.

Molecular variation at the apolipoprotein B gene locus in relation to lipids and cardiovascular disease: a systematic meta-analysis

Apolipoprotein B (apoB) is the sole protein component of low-density lipoprotein (LDL) and is thought to play an important role in atherogenesis. We performed a meta-analysis of the associations between the three most frequently investigated polymorphisms (XbaI, signal peptide insertion/deletion, EcoRI) in the apolipoprotein B (APOB) gene, lipid parameters, and the risk of ischemic heart disease (IHD). We restricted our analysis to Caucasians. Homozygotes for the XbaI X+ allele had significantly elevated levels of LDL cholesterol (LDL-C) and apoB, but a decreased risk (OR=0.80; 95%CI: 0.66-0.96) of IHD. Homozygosity for the signal peptide deletion allele was associated with similarly increased levels of LDL-C and apoB, and with an increased risk of IHD (OR=1.30; 95%CI: 1.08-1.58). Subjects homozygous for the rare EcoRI allele had significantly decreased levels of total and LDL cholesterol, but unaltered risk of IHD. We conclude that all three polymorphic apoB sites are associated with altered lipid levels, but not necessarily with a consistently altered risk of IHD. These data suggest that the relationship between apoB levels, hypercholesterolemia and IHD risk cannot have a simple molecular basis in the apoB gene.