Population genetic models in the study of aging and longevity in a Mennonite community

"Predicting" parental longevity from offspring endophenotypes: data from the Long Life Family Study (LLFS)

While there is evidence that longevity runs in families, the study of long-lived families is complicated by the fact that longevity-related information is available only for the oldest old, many of whom may be deceased and unavailable for testing, and information on other living family members, primarily descendents, is censored. This situation requires a creative approach for analyzing determinants of longevity in families. There are likely biomarkers that predict an individual's longevity, suggesting the possibility that those biomarkers which are heritable may constitute valuable endophenotypes for exceptional survival. These endophenotypes could be studied in families to identify human longevity genes and elucidate possible mechanisms of their influence on longevity. In this paper, we analyze data collected in the Long Life Family Study (LLFS) investigating whether indicators of physiological state, cognitive functioning and health/well-being among offspring predict longevity in parents. Good predictors can be used as endophenotypes for exceptional survival. Our analyses revealed significant associations between cumulative indices describing physiological state, as well as a number of offspring phenotypes, and parental lifespan, supporting both their familial basis and relevance to longevity. We conclude that the study of endophenotypes within families is a valid approach to the genetics of human longevity.

Familial Transmission of Human Longevity Among the Oldest-Old in China

This paper investigates the relationship between longevity of parents and exceptional longevity (survival to age 80 or older) of offspring, using data from the first three waves of the Chinese Longitudinal Healthy Longevity Survey. We apply the Fixed-Attributes Dynamics method and logistic regression models to the data. Results of both methods show that the familial transmission of longevity exists at very old ages, and the transmission is same-sex linked between parents and offspring; that is, there is a strong father-son resemblance of longevity and a strong mother-daughter resemblance of longevity, but a non-significant or weak association of longevity between father and daughter or between mother and son.

Parental effects on offspring longevity—evidence from 17th to 19th century reproductive histories

BACKGROUND

Family studies provide support for a modest genetic influence on offspring life span, although the magnitude of these correlations is small.

AIM

The study aimed to clarify the relative contributions of parental age at birth and overall parental longevity on offspring lifespan, and to identify the biological and cultural mechanisms.

SUBJECTS AND METHODS

Information was derived from two village genealogies (1650-1927) encompassing 9979 births (5315 males, 4664 females). Data selection was guided by the inclusion of information about parental age at birth and lifespan, offspring lifespan and cohort-specific life expectancy.

RESULTS

Parental age at reproduction displayed a negative association with offspring survivability, which was caused by a host of biological as well as environmental factors. In contrast, parental lifespan was positively associated with offspring age at death. These effects differed by parent's and child's sex.

CONCLUSION

The maternal age effect on female progeny is thought to be indicative of a preferential genetic load. From an evolutionary point of view, direct selection for maternal lifespan may be an adaptive strategy to enhance child survival prospects.

Genealogical data and the biodemography of human longevity

Biodemography of human longevity is an emerging interdisciplinary field of sociobiological research with deep historical roots. Two research questions are examined in this article: (1) What evidence is there for the familial transmission of human longevity?, and (2) what are the effects of parental age at reproduction on offspring longevity, and in particular, are there long-term adverse health consequences associated with the trend toward delayed reproduction? The ability of scientists to conduct biodemographic studies depends not only on merging theoretical and methodological elements from the biological and demographic/actuarial sciences, but unique sources of data and statistical methods must also be developed. In this article we describe how gencalogical data have been used for over a century to explore basic questions about human longevity, and how similar kinds of data now being developed are driving the formation of new testable research hypotheses in the field of biodemography.

Heritability of life span in the Old Order Amish

Although a familial contribution to human longevity is recognized, the nature of this contribution is largely unknown. We have examined the familial contribution to life span in the Old Order Amish (OOA) population of Lancaster County, Pennsylvania. Analyses were conducted on 1,655 individuals, representing all those born prior to 1890 and appearing in the most widely available genealogy, surviving until at least age 30 years, and with known date of death. Mean age at death (+/-SD) in this population was 70.7 +/- 15.6 years, and this did not change appreciably over time. Parental and offspring ages at death were significantly correlated, as were ages of death among siblings. Offspring longevity was correlated with longevity of both parents, and in more or less additive fashion. For example, mean offspring age at death was 69.4 +/- 15.3 years in individuals for whom both parents died before the age of 75 years (n = 280) and increased to 73.5 +/- 16.0 years in individuals for whom neither parent died before the age of 75 years (n = 311). These differences were highly significant (P = 0.006). We estimated heritability of life span to be 25% +/- 5%, suggesting that the additive effects of genes account for one quarter of the total variability in life span in the OOA. We conclude that longevity is moderately heritable in the OOA, that the genetic effects are additive, and that genetic influences on longevity are likely to be expressed across a broad range of ages. Published 2001 Wiley-Liss, Inc.

Inherited diseases in North American Mennonites: focus on Old Colony (Chortitza) Mennonites

The patterns of migration and the genetic disorders occurring among North American Mennonites are reviewed, and inherited conditions recently recognized in a religious and genetic isolate, the Old Colony (Chortitza) Mennonites, are described. Old Colony Mennonites are of Dutch/German origin and descend from approximately 400 founding families who settled in the Old Colony, Chortitza (the Ukraine, USSR) in the late 1700s, and then migrated to Canada and Central and South America in the past century. We investigated over 6 generations of a Canadian Old Colony kindred in which there was extensive intermarriage, and in whom 28 individuals developed diabetes mellitus. Insulin-dependent diabetes mellitus (IDDM) occurred in 14 affected individuals in 10 closely related sibships; the 11 living IDDM patients were all concordant for the immunogenetic marker HLA-DR4. Fourteen close relatives had other disorders of carbohydrate metabolism, including gestational diabetes and non-insulin-dependent diabetes mellitus. Other close relatives had autoimmune diseases, including rheumatoid arthritis, hyper- and hypothyroidism, multiple sclerosis, and red cell aplasia. Other inherited diseases, including Alport syndrome, congenital defects, and inborn errors of metabolism were also found in the kindred. In the almost exclusively (99%) Old Colony Mennonite public health district in which the kindred was ascertained, there were multiple cases of Tourette syndrome, of malformations (including congenital heart defects and cleft lip +/- palate), and familial clusters of inborn errors of metabolism. We report this Old Colony (Chortitza) Mennonite isolate because 1) there are large familial aggregations of tissue-specific autoimmune diseases, malformations, inborn errors of metabolism, and of some other conditions whose genetic basis is still unknown; 2) there are multiple cases of rare genetic conditions, 3) we have established a computerized genealogic data base on over 1,000 kindred members as well as a cryopreserved lymphocyte/DNA bank on over 100 closely related individuals with various genetic conditions; and 4) this religious isolate, which extends across North, Central, and South America, offers an excellent opportunity for studying the epidemiology and molecular genetics of both common and rare inherited diseases.

Inherited frailty and longevity

The lifespansof parents and children appearonly weakly related,even though parents affect their children’s longevity through both genetic and environmental influences. These influences can be summarizedas a correlation betweenparents’and children’s frailty. It isshownthat even ifchildren perfectly inherit their frailty from their parents, parents’ life spans explain little of the variance in children’s life spans, because the variance in life expectancies among people with different frailties is small compared with the variancein life spansamongpeopleat the same leveloffrailty. Byinterpreting frailty as a relative risk in a proportional-hazard model, longevity as a duration or waiting time, and inheritance as an invariance in relative risk over time, one can extend this result to repeatable events involving fertility, migration, marriage, unemployment, and so forth.

Transmissible and nontransmissible components of anthropometric variation in the Alexanderwohl Mennonites: I. Description and familial correlations

Data on 34 anthropometric measures from the Alexanderwohl Mennonite congregations of Kansas and Nebraska are presented. A factor analysis of these traits shows that body length and body width measures are distinct from each other as well as from measures of the head and face. Moreover, familial correlations estimated by maximum likelihood for all 34 traits tend to separate from each other along factor lines with correlations for body lengths being the highest and those for skinfolds and circumferences being the lowest. These results suggest the presence of various body "fields" which are under differing degrees of genetic and environmental control. We offer the term "functional multifactorial complex" as a means of referring to the joint genetic and environmental influences on these fields.

Genetic study of high longevity index populations

Five-year multidisciplinary study of longevity in the Georgian SSR made it possible to select two populations (Abkhazian and Imeretian), in which indices of longevity were much higher, than the average level for the rural population of the whole region. The distribution of polymorphic systems of red cell enzymes (adenilate kinase, esterase D, phosphoglucomutase I, acid phosphatase, 6-phosphogluconate dehydrogenase, glyoxalase I, lactate dehydrogenase, adenosine deaminase, glutamate pyruvate transaminase, phosphoglycolate phosphatase, phosphohexose isomerase) and serum proteins (haptoglobin, Gc-component and transferrin) was studied for genetic analysis of these populations. The results indicate that for all the studied loci the observed genotypic frequencies in both populations are distributed according to Hardy-Weinberg equilibrium. The genetic comparison of the studied populations with some other neighbouring populations did not reveal any genetic peculiarities and the both populations concord with the scheme of anthropological types of Hither Asia. The study of age-related changes of gene frequencies and heterozygosity showed some age-related fluctuations of genetic indices in all age groups, but the heterogeneous nature of these deviations indicate that they may be the result of random genetic processes.

Family resemblance for normal pulmonary function

Family resemblance for normal pulmonary function as measured by forced vital capacity and one second forced expiration volume is assessed using a path analysis model which incorporates sex differences in transmissibility of the phenotype from parents to offspring as well as in the effect of a correlated shared-sibling environment. Application of this model, called XTAU, to familial correlations indicates that transmissible factors, which may be genetic or cultural, accounts for 20-30% of the variation in these measures. Further, a pronounced same-sex-specific effect of the sibling environment is indicated which enhanced the observed correlation between same-sex siblings and diminished the observed correlation between opposite-sex siblings. These results are consistent with findings of twin studies of pulmonary function indicating high heritability for both FVC and FEV1.0. In addition, the complex multifactorial model of family resemblance for normal pulmonary function is shown to have implications for specifying causal models of pulmonary disorders such as asthma, bronchitis, allergic rhinitis, and chronic obstructive pulmonary disease.

A commingling analysis of quantitative neuromuscular performance in a Kansas Mennonite community

The method of commingling analysis is applied to distributions of six quantitative neuromuscular traits. Results show that only two of these traits may be described by the single normal distribution commonly associated with quantitative variables. The remaining four traits show significant skewness which is best accounted for by a mixture of three component distributions. The pattern of commingling found suggests the presence of a major (megaphenic) effect operating in these traits. Further, evidence is found which links the major effect in three of the four commingled traits to a single process which may be related to neurological control. The etiology of the major effect (i.e., whether genetic or environmental) cannot be determined from commingling analysis, but some suggestions are offered based upon the nature of the traits themselves and the major effects.