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PubMed2007

Gene-environment interdependence.

Behavioural genetics was initially concerned with partitioning population variance into that due to genetics and that due to environmental influences. The implication was that the two were separate and it was assumed that gene-environment interactions were usually of so little importance that they could safely be ignored. Theoretical considerations suggested that that was unlikely to be true and empirical findings are now accumulating on the demonstrated and replicated biological interactions between identified common single genetic variants and the operation of environmentally mediated risks. The paper outlines the evidence and considers why it is changing concepts in ways that matter.

Behavior↗
PubMed1976

Extensions to pedigree analysis. III. Variance components by the scoring method.

The classic variance components for simple polygenic traits - additive, dominance, and environmental variance - have traditionally been estimated from sample covariances between first-degree relatives. If data is gathered on pedigrees, this statistical procedure wastes information. Recently Elston & Stewart suggested an alternative likelihood procedure that uses all the information in a set of pedigrees. A refinement of their method based on the scoring technique gives rapidly converging maximum likelihood estimates of the variance components and of the male and female means. Tests of statistical hypotheses about the various parameters can then be made by the likelihood ratio method. Furthermore, using classical regression analysis, the estimated parameter values allow prediction of unknown trait values from known trait values within a pedigree. These methods should apply to traits like total finger ridge count and to quantitative measurements associated with disease traits. Since the model postulates independent environmental effects and no assortative mating, its utility in human behaviour genetics seems limited.

Female↗
PubMed2001

RuNAway Disease: A two cycle model for transmissible spongiform encephalopathies (TSEs) wherein SINE proliferation drives PrP overproduction.

BACKGROUND: Despite decades of research, the agent responsible for transmitting spongiform encephalopathies (TSEs) has not been identified. The Prion hypothesis, which dominates the field, supposes that modified host PrP protein, termed PrPSc, acts as the transmissible agent. This model fits the observation that TSE diseases elicit almost no immune reaction. Prion transmission has not been verified, however, as it has not been possible to produce pure PrPSc aggregates. One long-standing objection to the Prion model is the observation that TSE disease agents show classical genetic behaviours, such as reproducible strain variation, while also responding to selection for novel traits such as adaptation to new hosts. Moreover, evidence has been steadily accumulating that infectious titre is decoupled from the quantity (or even the presence) of PrPSc deposits. Rather awkwardly for the Prion hypothesis, PrP0/0 knockout mice have been found to incubate and transmit TSE agents (despite themselves being refractory to TSE disease). HYPOTHESIS: In this article, a new scheme, RuNAway, is proposed whereby uncontrolled proliferation of a type of parasitic gene, the small dispersed repeat sequences (SINEs), in somatic cells induces overproduction of PrP with pathogenic consequences. The RuNAway scheme involves twin tandem positive feedback loops: triggering the second loop leads to the pathogenic disease. This model is consistent with the long latency period and much shorter visible disease progression typical of TSEs.

Animals↗
PubMed1999

Functional complementation of the malvolio mutation in the taste pathway of Drosophila melanogaster by the human natural resistance-associated macrophage protein 1 (Nramp-1).

The malvolio (mvl) gene of Drosophila melanogaster encodes a protein with a high degree of homology to natural resistance-associated macrophage proteins (Nramps). This family of integral membrane proteins, many of which appear to function as cation transporters, is remarkably conserved in several phylogenetically distinct species. In Drosophila melanogaster, the protein Mvl is expressed in macrophages and in differentiated neurons; loss-of-function mutations lead to defects in gustatory behaviour. The human Nramp-1 protein was expressed in Drosophila melanogaster using the hsp70 promoter. Overexpression in normal animals does not lead to any alterations in their behaviour or physiology. In mutants, however, ubiquitous expression of human Nramp-1 can totally rescue the taste defect. This finding that Nramp-1 can complement the taste defect in mvl mutants provides a potent means of exploiting behavioural genetics to dissect the function of Nramp-1 and to identify other molecules involved with this transport system.

Animals↗
PubMed2000

Differential environmental factors in anorexia nervosa: a sibling pair study.

OBJECTIVES: Previous studies have explored differences in psychosocial and familial factors between women who develop anorexia nervosa and those who do not. However, these studies have generally used between-group comparisons. This study looks at the environmental factors which may be antecedents of anorexia nervosa looking at sister pairs where one had anorexia nervosa and the other did not. DESIGN: A paired design was used to compare anorexic women with an unaffected sister on a number of background variables, including sibling interaction, parental care, peer group characteristics and other events unique to the individual. METHODS: The Sibling Inventory of Differential Experience (SIDE) was used to determine non-shared environment. Out of an initial sample of 148 women with past or current anorexia nervosa, 28 were identified who had sisters with no reported history of eating disorders and who also consented to complete the questionnaire. RESULTS: Anorexic sisters perceived more maternal control and reported more antagonism towards and jealousy of their sisters than did unaffected sisters. In addition, anorexic women reported having had fewer friends and boyfriends than their sisters. CONCLUSIONS: These results confirm the perceived differences in background environment between women with and women without anorexia nervosa. These issues are discussed in relation to behavioural genetics, family dynamics and psychosexual development.

Adolescent↗
PubMed2002

The etiology of personality function: the University of British Columbia Twin Project.

The UBC Twin Project is an on-going study of personality and personality disorder that has collected personality data on approximately 1000 adult volunteer twin pairs. The primary purpose of the study is to develop and validate measures of the major forms of personality disorder as a quantitative alternative to the classificatory system first proposed by the DSM-III using the standard methods of personality and behavioural genetics research. To date, the study has explored the univariate and multivariate relationships between the major personality and personality disorder inventories, and their relationships to other psychopathologies including the mood and anxiety disorders and key psychological variables, such as cognitive ability, attachment and attitudes. The results have several implications for personality and personality disorders, most notably a rationalized diagnostic/nosological system to enhanced measurement instruments that index and reflect the influence of specific genetic and environmental influences.

Adult↗
PubMed2003

Twins and friendship.

A growing body of literature asserts the importance of friendships for a child's emotional wellbeing, behavioural adjustment and developmental attainment. However, few studies have examined friendships in the twin situation. This paper examines the literature on friendships among children who are twins and asks two questions: (1) What are the implications of the twin situation for friendship formation? (2) How can the twin situation inform theoretical knowledge concerning friendship formation in the general population? The discussion examines the implications of the twin situation for the size and nature of twin children's friendship pool and questions whether children who are twins are more likely to be adaptive or maladaptive in their social behaviour. The paper argues for the need to study the process and mechanisms in friendship formation among twin children because the findings might inform not only studies of friendship but also behavioural genetic research.

Friends↗
PubMed1993

Personality is indeterminate.

The so-called unique environmental factor in behaviour genetics research, the longitudinal instability of personality, and the unpredictability of human creativity are all manifestations of the same process. Thus a scientific explanation of any one of them should account for them all. That process, it is proposed, is the inherently indeterminate global dynamics of the human brain. The clear implication is that all social sciences have inherently indeterminate phenomena as their subject matter. Predictions of the results of an appropriately designed psychometric study based on this hypothesis are offered.

Adult↗
PubMed1999

Antigenic and genetic characterization of a putative hybrid transferrin-binding protein B from Neisseria meningitidis.

The transferrin-binding protein Bs (TbpBs) from the bacterium Neisseria meningitidis have been divided into two families according to genetic and antigenic features. TbpB from meningococcal strain B385 showed a molecular mass similar to that exhibited by TbpBs belonging to the high molecular mass family of TbpBs. TbpB was recognized by immunoassay using a specific serum directed against the TbpB of the reference strain for this family (strain M982). It was also recognized by a serum elicited against the TbpB of the reference strain for the low molecular mass family (strain B16B6). The tbpB gene from strain B385 was cloned and sequenced. The highest degree of sequence homology was found to be with the TbpBs belonging to the high molecular mass family, although a region of 14 amino acids that is only present in the TbpB from strain B16B6 was also found. This report illustrates a TbpB that shows hybrid antigenic and genetic behaviour.

Amino Acid Sequence↗
PubMedDate not supplied

[Obesity in children].

Obesity during childhood and adolescence is an increasingly common complaint in our daily clinical practice. The increase in its prevalence makes paediatrician worry about this disease, which is now considered an epidemic by the World Health Organisation. Obesity is a complex disease. Its aetiology is not yet clear, due to the multiple factors involved: environment, genetics, behaviour, life style, neuroendocrinology and metabolism. Persistent obesity increases the risk of suffering from diabetes, cardiovascular disease, hypertension, and gallbladder disease. The treatment of obesity is problematic and there are few patients who persist on a long term weight reduction programme. A multidisciplinary approach is therefore required. Paediatricians, dieticians, nurses, psychologists and psychiatrist should intervene in the treatment programme. Dietary changes must combine a decrease in energy intake and an increase in energy expenditure, inculcating both healthy eating habits and lifestyle without interfering in the child's growth and development.

Child↗
PubMed2001

The role of PPAR alpha in obesity.

Obesity is a rapidly increasing health problem in all developed countries. Overweight rarely occurs in isolation but as part of a complex pattern of metabolic abnormalities ("metabolic syndrome" or "syndrome X") consisting of hyperlipidemia, hypoalphalipoproteinemia, type II diabetes and atherosclerosis. The disorder is considerably influenced by genetic, behavioural and nutritional factors. Recent data indicate that a group of closely related nuclear receptors, the peroxisome proliferator-activated receptors (PPARs), may be involved in the metabolic changes ultimately leading to obesity. This review summarises the latest developments in the PPAR field, with particular emphasis being placed on the physiological function of PPAR alpha during various nutritional states, and the possible role of PPAR alpha in obesity.

Animals↗
PubMedDate not supplied

[The nature of the variability in the individual differences of the frequency characteristics of the alpha-rhythm EEG in 6- to 8-year-old children].

Behavioural genetic technique (model fitting) was used to study the genetic and environmental contributions to individual variability of power of the alpha-frequency band and its components (alpha 1 = 7.5-9.0 Hz; alpha 2 = 9.5-11.0 Hz; alpha 3 = 11.5-13.0 Hz) in different brain areas. 26 pairs of monozygotic and 22 pairs of dizygotic twins aged 6-8 years participated in EEG study. EEG was recorded from the frontal (F3, F4), central (C3, C4), temporal (T3, T4), parietal (P3, P4), and occipital (O1, O2) areas. Our study revealed that the nature of different alpha-components was different. It was found that the later in the ontogenesis a component of the alpha-frequency band became dominant in the EEG the less genetic factors contribute into the family resemblance.

Alpha Rhythm↗
PubMed1996

A decade of research on the natural history of HIV infection: Part 2. Cofactors.

Cofactors of HIV disease may be considered risk modifiers that are causally related to future disease course. The search for potential cofactors, of viral, host or environmental origin, may provide avenues for altering the natural history of HIV infection. Potential viral cofactors include viral strains, such as syncytium-inducing and nonsyncytium-inducing variants, and strains that are resistant to specific antiretroviral therapies. Although there is strong evidence that sexually transmitted diseases that lead to genital ulcers or abrasions are important cofactors of HIV transmission, their role as cofactors in HIV disease progression is less clear. Further study of agents such as human herpesviruses 6 and 8 and hepatitis C may shed light on the role of other infectious agents in progressive HIV disease. Far less research has been conducted on behavioural, genetic and sociodemographic factors that may influence HIV disease progression rates. Since current anti-HIV therapies do not offer a cure, but only a means of prolonging life, the identification of possible cofactors is critical.

Comorbidity↗
PubMed1997

[French expatriates in the tropics. One hundred years of health history].

It is difficult to synthesize, for the 20th century, the evolution of mortality among travellers, since they make up a heterogenous and elusive category. Data for soldiers sent abroad are the most easily available and suggest two rates in the decline of mortality: one before and one after the Pasteurian revolution. There is no direct link between demographic curves and optimistic or pessimistic biological theories which have alternatively sought to interpret the phenomenon of being "transplanted" in the tropics. Today, the debate remains open as to the respective roles of genetic, behavioural, and ecological factors in the adaptation of the individual and the group. Although traumatology comes first among risks associated with voyaging, infectious disease still occupies an important place in how travel is perceived, perhaps because it symbolizes coming into contact with "strangers".

Colonialism↗
PubMed1998

Categorical models of childhood disorder: a conceptual and empirical analysis.

In this review we explore the clinical and scientific status of categorical models of childhood disorder. Three themes are developed. First, the practical origins of standardised category-based diagnostic schemes are examined along with their contemporary philosophical and psychological significance. Next, the impact that these systems have had on the science of child psychopathology is explored. We look at their link to the medical model and the assumption that childhood disorders are categorical, endogenous, and dysfunctional in nature. We argue that these assumptions underpin the dominant paradigm in child psychopathology and so constrain empirical study and theory development. In the final section, the different ways in which researchers have responded to this link and its impact on science are presented. We present the sort of scientific realism associated with Meehl (1995) as the most appropriate basis for a philosophically respectable child psychopathology. Following this approach means unpacking the paradigmatic assumptions, including the assumption of the categorical structure of disorder, into hypotheses that are then put to empirical test. The sorts of data that would allow us to test the categorical hypothesis are identified. We conclude by discussing the results from three recent studies using behaviour genetic analysis of twin data that, in fact, lead us toward a rejection of this hypothesis. The implications for diagnostic and clinical practice of such a rejection are discussed.

Child↗
PubMed2000

Plasticity and the genetics of reproductive behaviour in the monocarpic perennial, Lobelia inflata (Indian tobacco).

The timing of reproduction is an important life-history variable, especially for organisms that die following a single reproductive episode, such as the monocarp Lobelia inflata. The propensity to initiate flowering (to bolt) under a given set of conditions is expected to be shaped by natural selection acting on the norms of reaction for bolting behaviour over, for example, changing photoperiods. We study the genetic basis of bolting and of the plasticity of bolting using three continuously changing photoperiod regimes over two generations in a growth chamber experiment. Multiple genotypes from three populations are tested under three different photoperiod treatments mimicking early, mid, and late 'summer' during both generations. The frequency of bolting ranges from 88% under long days to 1% under short days. The overall heritability (h2) of bolting is found to be high, and increases later in the flowering season. Genetic variance for bolting is explained by genetic variance for threshold size itself, rather than for capacity to attain a fixed threshold size: genotypes that bolt most readily tend to be those that bolt at a smaller rosette size. No significant heritability of the plasticity of bolting behaviour is detected. Similarly to within populations, variation at the among-population level exists for bolting behaviour. There is no evidence for genetic population differentiation with respect to plasticity for bolting: although plasticity differs among populations within a generation, this population effect is not consistent between the two generations of the experiment.

Asteraceae↗
PubMed1998

Complex limiting behaviour of multilocus genetic systems in cyclical environments.

Here we demonstrate that complex limiting behaviour (supercycles and chaotic-like phenomena) may arise in a rather broad and natural class of multilocus systems, both haploid and diploid, experiencing stabilizing selection with cyclically varying optima over a short period. These include loci with purely additive, dominant, or semidominant effects, with different types of their chromosome distribution. The observed complex dynamics appeared to manifest a certain stability with respect to disturbances of parameters specifying the structure of the selected system and environmental characteristics. This mode of multilocus dynamics by far exceeds the potential attainable under ordinary selection models resulting in simple behaviour. It may represent a novel evolutionary mechanism increasing genetic diversity over long time periods. This novel mechanism could contribute to the observation that biological diversity has increased over geological time regardless of the well-known massive extinctions.

Animals↗
PubMed1998

Self-injurious behaviour as part of genetic syndromes.

BACKGROUND: The purpose of this paper is to review the association between genetic syndromes and self-injurious behaviour. METHOD: The information available from the literature on the subject of self-injurious behaviours and genetic syndromes was collated and presented with a critical appraisal. RESULTS: Self-injurious behaviours are associated with some genetic syndromes. However, the causal relationship between the genetic syndromes and the self-injurious behaviour remains far from clear. CONCLUSIONS: Although self-injurious behaviour has been shown to be the part of a broader phenotype in many genetic disorders, the specificity and sensitivity of these behaviours in this context remain unclear.

Brain Damage, Chronic↗