XXIV.—On the Sampling Variance of Heritability Estimates derived from Variance Analyses

Osborne, R. T.; Paterson, W. S. B.

doi:10.1017/s0080455x0000998x

Cited by 65 publications

(31 citation statements)

References 7 publications

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“…22 The degree of genetic determination from the cross analysis was also estimated by the method of Falconer. 21 The phenotypic variance at the nonsegregating generation is theoretically due to environmental cause only, and that at the segregating generation can be attributable to both genetic and environmental causes.…”

Section: Males Of 23 Inbred Strains'mentioning

confidence: 99%

Heart size in inbred strains of rats. Part 1. Genetic determination of the development of cardiovascular enlargement in rats.

Tanase¹,

Yamori²,

Hansen³

et al. 1982

Hypertension

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SUMMARY The heart and aorta weights in 23 strains of rats and the four-way cross generation among the M520/N, SHRSP/N, SHR/N, and WKY/N strains were investigated in relation to their blood pressure in an attempt to characterize cardiovascular enlargement (increased weight of heart and aorta) from a genetic aspect. The distribution of blood pressure in these strains at 10 weeks of age was clearly divided into hypertensive and normotensive groups. In the hypertensive group, heart weight increased in proportion to blood pressure. In contrast, there was no relationship between blood pressure and heart weight in the normotensive group in spite of large strain differences in heart weights. The result of variance analysis exhibited a significant strain difference in heart weight, and the degree of genetic determination was estimated to be 65%-75%. A similar genetic influence was apparent for normotensive strains excluding hypertensive strains. The distribution of blood pressures in the four-way cross generation showed the segregation of three phenotypes consisting of normotensive, intermediate and hypertensive groups. A large variability was seen in heart weight of each group. However, the increase in average heart weight of these three groups was very small. The degree of genetic determination from the cross analysis was estimated to be 45%-65%. These results indicate that heart weight is a highly heritable trait, and that the effect of genetic factors on cardiac enlargement is larger than that of blood pressure. A similar result was obtained for the aorta weight. However, the effect of genetic factors was less important for aorta weight than for heart weight since the degree of genetic determination was estimated to be 45%-65% from the strain comparison and 35%-60% from the cross analysis. (Hypertension 4: 864-872, 1982) KEY WORDS • hypertrophy • heart • aorta • hypertension genetic factor • spontaneously hypertensive rat A S described by Bright 1 in 1839, cardiac hypertrophy was one of the first obvious changes noted in hypertension. Since then, cardiac hypertrophy has been investigated not only in humans with hypertension but also in animals with experimentally induced hypertension. In general, cardiac hypertrophy has been regarded as a secondary response to increased pressure because the heart enlarges in response to the increment in pressure load. "1 However, it was pointed out that there were many patients with- Received September 4, 1981; accepted April 26, 1982. out cardiac hypertrophy in spite of a marked hypertension. 5 -6 The spontaneously hypertensive rat (SHR) strain developed by Okamoto 7 appears to be an appropriate animal model for the study of cardiac hypertrophy associated with hypertension since the hypertension resembles human essential hypertension in many respects.8 It is well known that the SHR strain develops left ventricular hypertrophy.9 " 12 It has been recently reported that the increase of left ventricular wall mass in the SHR is initiated early in life before elevation of blood pres...

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Section: Males Of 23 Inbred Strains'mentioning

confidence: 99%

Heart size in inbred strains of rats. Part 1. Genetic determination of the development of cardiovascular enlargement in rats.

Tanase¹,

Yamori²,

Hansen³

et al. 1982

Hypertension

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“…Several methods for calculating confidence intervals for heritability estimators have been proposed. The sampling variance of broad-sense or familymean heritability, both calculated from two variance components, has received considerable attention, especially for balanced data (Osborne and Paterson 1952;Knapp et al 1985Knapp et al , 1989Knapp and Bridges 1987;Koots and Gibson 1996;Visscher 1998;Burch and Harris 2005). For unbalanced data and under normality assumptions, Harville and Fenech (1985) developed a method to calculate exact confidence intervals on a ratio of two variance components, which allows one to give exact confidence intervals for broad-sense heritability.…”

Section: Discussionmentioning

confidence: 99%

Reliable confidence intervals in quantitative genetics: narrow-sense heritability

2007

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Many quantitative genetic statistics are functions of variance components, for which a large number of replicates is needed for precise estimates and reliable measures of uncertainty, on which sound interpretation depends. Moreover, in large experiments the deaths of some individuals can occur, so methods for analysing such data need to be robust to missing values. We show how confidence intervals for narrow-sense heritability can be calculated in a nested full-sib/half-sib breeding design (males crossed with several females) in the presence of missing values. Simulations indicate that the method provides accurate results, and that estimator uncertainty is lowest for sampling designs with many males relative to the number of females per male, and with more females per male than progenies per female. Missing data generally had little influence on estimator accuracy, thus suggesting that the overall number of observations should be increased even if this results in unbalanced data. We also suggest the use of parametrically simulated data for prior investigation of the accuracy of planned experiments. Together with the proposed confidence intervals an informed decision on the optimal sampling design is possible, which allows efficient allocation of resources.

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“…(5) (6) It is known from quantitative genetics that the estimated intraclass correla tion coefficients, t, or t2 is h2/4 for additive genetic effects and the sampling variance of tj and t2 can be obtained after Osborne and Paterson [1952] with the assumption that tx = t2 = t. by:…”

Section: Half-sibling Analysismentioning

confidence: 99%

Sampling Variances in Twin and Sibling Studies of Man

Kang¹,

Lindemann²,

Christian³

et al. 1974

Hum Hered

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The sampling variances in twin and sibling studies of man for estimation of intraclass correlation coefficients and their relation to heritabilities are evaluated. For twins and full-sibs the higher the estimated heritability of a trait the smaller the sampling variance. With increase in the number of twin sets or of full-sibships studied, the sampling variances decrease by their proportions. Twin and full-sib studies with lower heritabilities (h² < 0.25) need at least 50 sibships to obtain a significant estimate. Using half-sibs to estimate heritabilities, increase of the offspring number from the same parent would be more efficient for reducing the sampling variance of the heritability compared with increases of half-sibship families. However, because of the limited number of offspring per family in modern man, the efficiency of the half-sib design could be increased by the large number of monozygotic twin families. It appears that with only 2 or 3 children per full-sibship family, approximately 100 half-sibships are needed for significant estimate of heritability.

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XXIV.—On the Sampling Variance of Heritability Estimates derived from Variance Analyses

Abstract: SynopsisA method is presented by which the sampling variance of all heritability estimates derived from ratios involving variance components may be found.

Cited by 65 publications

References 7 publications

Heart size in inbred strains of rats. Part 1. Genetic determination of the development of cardiovascular enlargement in rats.

Heart size in inbred strains of rats. Part 1. Genetic determination of the development of cardiovascular enlargement in rats.

Reliable confidence intervals in quantitative genetics: narrow-sense heritability

Sampling Variances in Twin and Sibling Studies of Man

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