The advantages of analysing human variation using twins and twin half-sibs and cousins

Haley, Chris; Last, Krystyna

doi:10.1038/hdy.1981.78

Cited by 10 publications

(4 citation statements)

References 20 publications

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“…A number of statistical approaches have been developed to account for the fetal genotype and the correlated maternal genotype to address such confounding (36)(37)(38). In our components of variance model for correlations between relatives, additive genetic covariance between maternal and fetal genotypes would be confounded with estimates of the maternal genetic effect (39).…”

Section: Molecular Findings' Support Of a Fetal Genetic Contributionmentioning

confidence: 99%

Fetal and Maternal Genes’ Influence on Gestational Age in a Quantitative Genetic Analysis of 244,000 Swedish Births

York¹,

Eaves²,

Lichtenstein³

et al. 2013

American Journal of Epidemiology

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Although there is increasing evidence that genetic factors influence gestational age, it is unclear to what extent this is due to fetal and/or maternal genes. In this study, we apply a novel analytical model to estimate genetic and environmental contributions to pregnancy history records obtained from 165,952 Swedish families consisting of offspring of twins, full siblings, and half-siblings (1987-2008). Results indicated that fetal genetic factors explained 13.1% (95% confidence interval (CI): 6.8, 19.4) of the variation in gestational age at delivery, while maternal genetic factors accounted for 20.6% (95% CI: 18.1, 23.2). The largest contribution to differences in the timing of birth were environmental factors, of which 10.1% (95% CI: 7.0, 13.2) was due to factors shared by births of the same mother, and 56.2% (95% CI: 53.0, 59.4) was pregnancy specific. Similar models fit to the same data dichotomized at clinically meaningful thresholds (e.g., preterm birth) resulted in less stable parameter estimates, but the collective results supported a model of homogeneous genetic and environmental effects across the range of gestational age. Since environmental factors explained most differences in the timing of birth, genetic studies may benefit from understanding the specific effect of fetal and maternal genes in the context of these yet-unidentified factors.

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Section: Molecular Findings' Support Of a Fetal Genetic Contributionmentioning

confidence: 99%

Fetal and Maternal Genes’ Influence on Gestational Age in a Quantitative Genetic Analysis of 244,000 Swedish Births

York¹,

Eaves²,

Lichtenstein³

et al. 2013

American Journal of Epidemiology

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show abstract

“…It is also easy to extend the classical twin design by including other informative relationships in the analysis including siblings (47,48), parents of twins (25,49,50), the offspring of MZ and DZ twins (51,52), and the spouses of twins (53)(54)(55). These designs can quantify the effects of phenotypic assortment and vertical cultural transmission, which the classical twin study cannot do.…”

Section: S T a T I S T I C A L C O R N E R Genetically Informative Dementioning

confidence: 99%

Genetics in Psychosomatic Medicine: Research Designs and Statistical Approaches

McCaffery

Snieder

Dong

et al. 2007

Psychosomatic Medicine

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It has become increasingly clear that genetic factors influence many of the behaviors and disease endpoints of interest to psychosomatic medicine researchers. There has been increasing interest in incorporating genetic variation markers into psychosomatic research. In this Statistical Corner article, we build on the valuable experiences gained during two workshops for "starters in the field" at the American Psychosomatic Society and the Society for Psychophysiological Research to review two common genetically informative research designs for human studies: twin and genetic association studies. We outline statistical techniques for each and, for genetic association studies, address special topics, including the treatment of race and ethnicity, gene ϫ gene and gene ϫ environment interaction, haplotype analysis, and power and sample size. Finally, we discuss the issue of nonreplication and interpretation of results derived from genetic association studies. We hope this overview of twin and genetic association designs will support and stimulate thoughtful applications of genetic approaches within psychosomatic medicine. Key words: statistics, genetics, twin studies.MZ ϭ monozygotic; DZ ϭ dizygotic; SES ϭ socioeconomic status; SEM ϭ structural equation modeling; SBP ϭ systolic blood pressure; HWE ϭ Hardy-Weinberg equilibrium; SNP ϭ single nucleotide polymorphism; VNTR ϭ varying number of tandem repeats; LD ϭ linkage disequilibrium; TDT ϭ transmission disequilibrium test.

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“…To do this, the well tried and experimentally tested methods of biometrical genetics [13,14] have been utilised [7,8].…”

Section: The Modelsmentioning

confidence: 99%

Detecting Sex-Associated Variation With the Families of MZ and DZ Twins

Haley

1984

Acta genet. med. gemellol.: twin res.

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Phenotypic variation in human population may contain contributions from a number of different sex-associated genetic influences. These influences include maternal effects, the effects of sex-linked loci, and the effects of sex-limited autosomally linked loci. The families produced by MZ and DZ twins provide statistics which permit the detection and estimation of these effects. In particular, they provide statistics derived from various types of age-matched half-sibs and cousins in addition to those derived from the more usually studied full-sib or parent-offspring relationships. Specific models for genetic maternal effects, sex-linkage and sex-limitation are used to explore the use of extended twin design for the detection of and the discrimination between various sex-associated effects. The sample sizes required to detect maternal effects and sex-linkage were considered for some simple cases and it is concluded that comparison derived from the progeny of twins will often provide better tests for these effects than those derived from parent-offspring comparison.

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The advantages of analysing human variation using twins and twin half-sibs and cousins

Cited by 10 publications

References 20 publications

Fetal and Maternal Genes’ Influence on Gestational Age in a Quantitative Genetic Analysis of 244,000 Swedish Births

Fetal and Maternal Genes’ Influence on Gestational Age in a Quantitative Genetic Analysis of 244,000 Swedish Births

Genetics in Psychosomatic Medicine: Research Designs and Statistical Approaches

Detecting Sex-Associated Variation With the Families of MZ and DZ Twins

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