Biomedical subjects

Marian Beekman

Publications and source records attributed to Marian Beekman.

13 recordsLinked to original sources

PubMed2006

Evidence of genetic enrichment for exceptional survival using a family approach: the Leiden Longevity Study.

We conducted a sib pair study in very old subjects for the purpose of mapping longevity loci. In the present analysis, we explore whether our recruitment strategy has resulted in a population enriched for a heritable component for exceptional longevity. Our study includes families with at least two long-living siblings (men aged 89 years or above; women aged 91 years or above). Data were collected on date of birth and, if applicable, date of death of parents, brothers and sisters, offspring, and spouses of the long-living participants. Standardised mortality ratios (SMRs) compared with the general Dutch population, were calculated. The SMR for all siblings of the long-living participants was 0.66 (95% CI 0.60-0.73). A similar survival benefit was also observed in the parents (SMR=0.76, 95% CI 0.66-0.87) and in the offspring of the long-living subjects (SMR=0.65, 95% CI 0.51-0.80). The SMR of the spouses of the long-living subjects was 0.95 (95% CI 0.82-1.12). The familial clustering of extended survival is unlikely to be caused by ascertainment bias, because in all analyses the long-living participants were excluded. Moreover, it is also unlikely to be caused by environmental factors, because the spouses of the long-living participants had a mortality risk comparable with the general Dutch population, whereas they share the same environment. We conclude that our sample is genetically enriched for extreme survival.

Aged, 80 and over↗

PubMed2006

Chromosome 4q25, microsomal transfer protein gene, and human longevity: novel data and a meta-analysis of association studies.

Recently, chromosome 4q25 was linked to exceptional human longevity, and a haplotype of the positional candidate microsomal transfer protein (MTP) gene was associated to the phenotype in U.S. Caucasians. We investigated whether linkage to 4q25 could be detected in 164 nonagenarian sibships of the Leiden Longevity Study. Additionally, we compared the MTP -493G/T and Q95H allele and haplotype frequencies in the Leiden Longevity Study (379 nonagenarians, 525 of their offspring, and 251 partners of their offspring) and in the Leiden 85-Plus Study (655 octogenarians and 244 young controls). The latter study population was followed for at least 7 years, providing the opportunity to perform also prospective analyses using the longitudinal data. We found neither evidence for linkage at 4q25 nor association of the MTP locus with longevity in nonagenarian individuals. Meta-analyses of all previous studies implied that the association in U.S. Caucasians may have its source in admixture of the U.S. control population rather than in the genetic effect of the locus on exceptional longevity.

Adult↗

PubMed2006

Lipoprotein particle profiles mark familial and sporadic human longevity.

BACKGROUND: Genetic and biochemical studies have indicated an important role for lipid metabolism in human longevity. Ashkenazi Jewish centenarians and their offspring have large low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles as compared with control individuals. This profile also coincided with a lower prevalence of disease. Here, we investigate whether this observation can be confirmed for familial longevity in an outbred European population and whether it can be extended to sporadic longevity in the general population. METHODS AND FINDINGS: NMR-measured lipoprotein profiles were analyzed in 165 families from the Leiden Longevity Study, consisting of 340 long-lived siblings (females >91 y, males >89 y), 511 of their offspring, and 243 partners of the offspring. Offspring had larger (21.3 versus 21.1 nm; p = 0.020) and fewer (1,470 versus 1,561 nmol/l; p = 0.011) LDL particles than their same-aged partners. This effect was even more prominent in the long-lived siblings (p < 10(-3)) and could be pinpointed to a reduction specifically in the concentration of small LDL particles. No differences were observed for HDL particle phenotypes. The mean LDL particle sizes in 259 90-y-old singletons from a population-based study were similar to those in the long-lived siblings and thus significantly larger than in partners of the offspring, suggesting that the relevance of this phenotype extends beyond familial longevity. A low concentration of small LDL particles was associated with better overall health among both long-lived siblings (p = 0.003) and 90-y-old singletons (p = 0.007). CONCLUSIONS: Our study indicates that LDL particle profiles mark both familial and sporadic human longevity already in middle age.

Aged↗

PubMed2005

Shuttling between species for pathways of lifespan regulation: a central role for the vitellogenin gene family?

Studies to find genes that affect maximum lifespan aim at identifying important determinants of ageing that may be universal across species. Model organisms show insulin signalling can play an important role in ageing. In view of insulin resistance, such loci can also be important in human ageing and health. The study of long-lived humans and their children points to the relevance of lipoprotein profiles and particle size for longevity. If ageing pathways are conserved, then the genes mediating such pathways may also be conserved. Cross-species sequence comparisons of potential longevity loci may reveal whether the pathways that they represent are central themes in lifespan regulation. Using bioinformatic tools, we performed a sequence comparison of the genes involved in lipid metabolism identified in humans as potential longevity loci. This analysis revealed that lipid storage and transport may be a common theme related to longevity in humans, honeybees and nematodes. Here, the vitellogenin family emerges as a potential key connection between lipid metabolism and the insulin/IGF-1 signalling pathway.

Animals↗

PubMed2005

Meta-analysis of four new genome scans for lipid parameters and analysis of positional candidates in positive linkage regions.

Lipid levels in plasma strongly influence the risk for coronary heart disease. To localise and subsequently identify genes affecting lipid levels, we performed four genome-wide linkage scans followed by combined linkage/association analysis. Genome-scans were performed in 701 dizygotic twin pairs from four samples with data on plasma levels of HDL- and LDL-cholesterol and their major protein constituents, apolipoprotein AI (ApoAI) and Apolipoprotein B (ApoB). To maximise power, the genome scans were analysed simultaneously using a well-established meta-analysis method that was newly applied to linkage analysis. Overall LOD scores were estimated using the means of the sample-specific quantitative trait locus (QTL) effects inversely weighted by the standard errors obtained using an inverse regression method. Possible heterogeneity was accounted for with a random effects model. Suggestive linkage for HDL-C was observed on 8p23.1 and 12q21.2 and for ApoAI on 1q21.3. For LDL-C and ApoB, linkage regions frequently coincided (2p24.1, 2q32.1, 19p13.2 and 19q13.31). Six of the putative QTLs replicated previous findings. After fine mapping, three maximum LOD scores mapped within 1 cM of major candidate genes, namely APOB (LOD=2.1), LDLR (LOD=1.9) and APOE (LOD=1.7). APOB haplotypes explained 27% of the QTL effect observed for LDL-C on 2p24.1 and reduced the LOD-score by 0.82. Accounting for the effect of the LDLR and APOE haplotypes did not change the LOD score close to the LDLR gene but abolished the linkage signal at the APOE gene. In conclusion, application of a new meta-analysis approach maximised the power to detect QTLs for lipid levels and improved the precision of their location estimate.

Adolescent↗

PubMed2005

Reduced insulin/IGF-1 signalling and human longevity.

Evidence is accumulating that aging is hormonally regulated by an evolutionarily conserved insulin/IGF-1 signalling (IIS) pathway. Mutations in IIS components affect lifespan in Caenorhabditis elegans, Drosophila melanogaster and mice. Most long-lived IIS mutants also show increased resistance to oxidative stress. In D. melanogaster and mice, the long-lived phenotype of several IIS mutants is restricted to females. Here, we analysed the relationship between IIS signalling, body height and longevity in humans in a prospective follow-up study. Based on the expected effects (increased or decreased signalling) of the selected variants in IIS pathway components (GHRHR, GH1, IGF1, INS, IRS1), we calculated composite IIS scores to estimate IIS pathway activity. In addition, we analysed the relative impact on lifespan and body size of the separate variants in multivariate models. In women, lower IIS scores are significantly associated with lower body height and improved old age survival. Multivariate analyses showed that these results were most pronounced for the GH1 SNP, IGF1 CA repeat and IRS1 SNP. In females, for variant allele carriers of the GH1 SNP, body height was 2 cm lower (P = 0.007) and mortality 0.80-fold reduced (P = 0.019) when compared with wild-type allele carriers. Thus, in females, genetic variation causing reduced IIS activation is beneficial for old age survival. This effect was stronger for the GH1 SNP than for variation in the conserved IIS genes that were found to affect longevity in model organisms.

Aged↗

PubMed2004

Combined association and linkage analysis applied to the APOE locus.

Combined association and linkage analysis is a powerful tool for pinpointing functional quantitative traits (QTLs) responsible for regions of significant linkage identified in genome-wide scans. We applied this technique to apoE plasma levels and the APOEepsilon2/epsilon3/epsilon4 polymorphism in two Dutch twin cohorts of different age ranges. Across chromosome 19, short tandem repeats and the APOEepsilon2/epsilon3/epsilon4 polymorphism were genotyped in adolescent (aged 13-22 years) and adult (aged 34-62 years) Dutch twins. In both samples, evidence for indicative linkage with plasma apoE levels was found (maximum LOD score (MLS)=0.8, MLS=2.5, respectively) at 19q13.32. These linkage regions included the APOE locus. As expected, the APOEepsilon2/epsilon3/epsilon4 polymorphism was strongly associated with apoE plasma levels in both samples. An extension of the between/within families association test developed by Fulker et al. ([1999] Am. J. Hum. Genet. 64:259-267) showed that these associations were not due to population stratification. The combined association and linkage analyses revealed that the association of the APOEepsilon2/epsilon3/epsilon4 polymorphism with apoE plasma levels completely explained the linkage in the adolescent twins and partly in the adult twins.

Adolescent↗

PubMed2004

Variation in the SHC1 gene and longevity in humans.

Mice in which the p66(SHC) specific region of the SHC gene is deleted live 30% longer without apparent disease. These mice have lower levels of oxidative stress and apoptosis, both of which have been linked to old age survival in man. This makes SHC1 an important candidate gene for longevity in humans. We found no variations in the p66 specific region of the SHC1 gene in 30 young and 30 extreme long-lived subjects. Thus in man, no common sequence variations occur in p66 specific region of the SHC1 gene. In two independent cohorts of respectively 730 and 563 subjects aged 85 and over, we tested the only known non-synonymous polymorphism, Met(410)Val, for association with longevity using a prospective follow-up design. In the first cohort, we found increasing valine allele frequency in three strata of increasing age at death (2.8-5.2%). Moreover, compared to Met/Met carriers, mortality rate was a factor of 0.71 (95% CI 0.45-1.13) reduced for Met/Val carriers in the combined cohorts, with similar risk estimates in both cohorts. Low valine allele frequency resulted, however, in low power to detect statistical significance. These data suggest that an association between the Met(410)Val polymorphism and longevity in humans may exist.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Copulas in QTL mapping.

The standard variance components method for mapping quantitative trait loci is derived on the assumption of normality. Unsurprisingly, statistical tests based on this method do not perform so well if this assumption is not satisfied. We use the statistical concept of copulas to relax the assumption of normality and derive a test that can perform well under any distribution of the continuous trait. In particular, we discuss bivariate normal copulas in the context of sib-pair studies. Our approach is illustrated by a linkage analysis of lipoprotein(a) levels, whose distribution is highly skewed. We demonstrate that the asymptotic critical levels of the test can still be calculated using the interval mapping approach. The new method can be extended to more general pedigrees and multivariate phenotypes in a similar way as the original variance components method.

Analysis of Variance↗

PubMed2003

Evidence for a QTL on chromosome 19 influencing LDL cholesterol levels in the general population.

The genetic basis of cardiovascular disease (CVD) with its complex etiology is still largely elusive. Plasma levels of lipids and apolipoproteins are among the major quantitative risk factors for CVD and are well-established intermediate traits that may be more accessible to genetic dissection than clinical CVD end points. Chromosome 19 harbors multiple genes that have been suggested to play a role in lipid metabolism and previous studies indicated the presence of a quantitative trait locus (QTL) for cholesterol levels in genetic isolates. To establish the relevance of genetic variation at chromosome 19 for plasma levels of lipids and apolipoproteins in the general, out-bred Caucasian population, we performed a linkage study in four independent samples, including adolescent Dutch twins and adult Dutch, Swedish and Australian twins totaling 493 dizygotic twin pairs. The average spacing of short-tandem-repeat markers was 6-8 cM. In the three adult twin samples, we found consistent evidence for linkage of chromosome 19 with LDL cholesterol levels (maximum LOD scores of 4.5, 1.7 and 2.1 in the Dutch, Swedish and Australian sample, respectively); no indication for linkage was observed in the adolescent Dutch twin sample. The QTL effects in the three adult samples were not significantly different and a simultaneous analysis of the samples increased the maximum LOD score to 5.7 at 60 cM pter. Bivariate analyses indicated that the putative LDL-C QTL also contributed to the variance in ApoB levels, consistent with the high genetic correlation between these phenotypes. Our study provides strong evidence for the presence of a QTL on chromosome 19 with a major effect on LDL-C plasma levels in outbred Caucasian populations.

Adolescent↗

PubMed2003

Two-locus linkage analysis applied to putative quantitative trait loci for lipoprotein(a) levels.

Plasma levels of lipoprotein(a) - Lp(a) - are associated with cardiovascular risk (Danesh et al., 2000) and were long believed to be influenced by the LPA locus on chromosome 6q27 only. However, a recent report of Broeckel et al. (2002) suggested the presence of a second quantitative trait locus on chromosome 1 influencing Lp(a) levels. Using a two-locus model, we found no evidence for an additional Lp(a) locus on chromosome 1 in a linkage study among 483 dizygotic twin pairs.

Adolescent↗

PubMed2002

Heritabilities of apolipoprotein and lipid levels in three countries.

This study investigated the influence of genes and environment on the variation of apolipoprotein and lipid levels, which are important intermediate phenotypes in the pathways toward cardiovascular disease. Heritability estimates are presented, including those for apolipoprotein E and AII levels which have rarely been reported before. We studied twin samples from the Netherlands (two cohorts; n = 160 pairs, aged 13-22 and n = 204 pairs, aged 34-62), Australia (n = 1362 pairs, aged 28-92) and Sweden (n = 302 pairs, aged 42-88). The variation of apolipoprotein and lipid levels depended largely on the influences of additive genetic factors in each twin sample. There was no significant evidence for the influence of common environment. No sex differences in heritability estimates for any phenotype in any of the samples were observed. Heritabilities ranged from 0.48-0.87, with most heritabilities exceeding 0.60. The heritability estimates in the Dutch samples were significantly higher than in the Australian sample. The heritabilities for the Swedish were intermediate to the Dutch and the Australian samples and not significantly different from the heritabilities in these other two samples. Although sample specific effects are present, we have shown that genes play a major role in determining the variance of apolipoprotein and lipid levels in four independent twin samples from three different countries.

Adolescent↗

PubMedDate not supplied

Variation in the human TP53 gene affects old age survival and cancer mortality.

Longevity may depend on a balance between tumor suppression and tissue renewal mechanisms [Campisi, J., 2003. Cancer and ageing: rival demons? Nat. Rev. Cancer 3 (5), 339-349]. Mice with constitutively activated p53 are almost cancer free but their life span is reduced and accompanied by early tissue atrophy [Tyner et al., 2002. p53 mutant mice that display early ageing-associated phenotypes. Nature 415 (6867) 45-53]. Replacement of arginine (Arg) by proline (Pro) at position 72 of human p53 decreases its apoptotic potential [Dumont et al., 2003. The codon 72 polymorphic variants of p53 have markedly different apoptotic potential. Nat. Genet. 33 (3), 357-365] providing a tool to test for a similar trade-off in humans. Using a formal meta-analysis of the published literature we show that carriers of the TP53 codon 72 Pro/Pro genotype have an increased cancer risk compared to Arg/Arg carriers (p<0.05). Next, in a prospective study of 1226 people aged 85 years and over we show that carriers of the Pro/Pro genotype have a 41% increased survival (p = 0.032) despite a 2.54 fold increased (p = 0.007) proportional mortality from cancer. It is suggested that human p53 protect against cancer but at a cost of longevity.

Aged↗