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PubMed1979

The use of heritabilities of anthropometric measures and performance tests in personnel selection.

An analogy exists between the mathematical models of psychological test theory and quantitative genetics. From this analogy we can conclude, that longitudinal correlation and heritability in the broad sense are equivalent expressions for the reliability in the long run. Since long-range prediction is the aim of index construction for personnel selection in athletics and other applied fields, we recommend to use heritability as a weighting factor for phenotypic scores in order to calculate true scores and to eliminate error variance.

Anthropometry↗
PubMed1978

[Estimation of the heritability of hair and eye color].

In the present study the colours of hair are regarded as quantitative genetic characters. The genetic and environmental components of the total variance of the characters are determined by analysis of correlation between parents and children as well as full sibs. An analysis of correlation coefficients makes it possible to further examine whether autosomal dominance or X-linked factors play a role in the inheritance. The correlations between the parents make the genetical analysis more complicated as they raise the correlation coefficients between relatives. The estimates of heritability are 0.61 (hair-colour) and 0.80 (eye-colour). These estimates may serve as preliminary values of orientation. Only further studies will show whether the relative large part of the variance caused by the environment can be confirmed. Dominance may play a small role in the case of hair colour, while it seems to be absent in eye-colour. There are no sufficient indications of X-linked factors for both characters.

Adult↗
PubMed1978

Logical, epistemological and statistical aspects of nature-nurture data interpretation.

In this paper the nature of the reasoning processes applied to the nature-nurture question is discussed in general and with particular reference to mental and behavioral traits. The nature of data analysis and analysis of variance is discussed. Necessarily, the nature of causation is considered. The notion that mere data analysis can establish "real" causation is attacked. Logic of quantitative genetic theory is reviewed briefly. The idea that heritability is meaningful in the human mental and behavioral arena is attacked. The conclusion is that the heredity-IQ controversy has been a "tale full of sound and fury, signifying nothing". To suppose that one can establish effects of an intervention process when it does not occur in the data is plainly ludicrous. Mere observational studies can easily lead to stupidities, and it is suggested that this has happened in the heredity-IQ arena. The idea that there are racial-genetic differences in mental abilities and behavioral traits of humans is, at best, no more than idle speculation.

Analysis of Variance↗
PubMed1984

[Quantitative value of the hallux pattern: mother-child correlation].

Mother-child correlations based upon the ridge-counts of the patterns of the hallucal areas of the soles were computed and compared with the results from finger-tips and palms. The results which are to be found in the hallucal areas of the sole join seamless to those known from finger and hand characters and show that the ridge-count of the hallucal pattern is in the same way suitable for quantitative genetic analysis of dermatoglyphics as the generally accepted dermatoglyphic counts.

Adult↗
PubMed1978

[Reliability, heritability, correlation in longitudinal studies (author's transl)].

An analogy exists between the mathematical models of psychological test theory and quantitative genetics, as well as between the parameters, reliability and heritability, derived from these models. With the same results, heritability and correlation in longitudinal studies are only different approaches to the same problem, the reliability of measurement in the long run, that is of fundamental consequence for personnel selection.

Anthropometry↗
PubMed1995

Ten allelic apolipoprotein[a] 5' flanking fragments exhibit comparable promoter activities in HepG2 cells.

Plasma levels of the atherogenic lipoprotein[a] represent a quantitative genetic trait that is primarily controlled by the polymorphic apolipoprotein[a] locus on chromosome 6q. The more than 1000-fold variation in lipoprotein[a] plasma levels is explained to a large extent by a remarkable size polymorphism of the apolipoprotein[a] gene which is translated into apolipoprotein[a] isoforms and by unidentified sequence variation in apo[a]. In a recent report, sequence variation in a 1.5 kb fragment from the 5' flanking region of the apolipoprotein[a] gene was associated with different promoter activities, which led to the suggestion that transcriptional control of the apolipoprotein[a] gene might contribute significantly to lipoprotein[a] plasma levels. We have used a reporter gene assay to compare the promoter activities of these 1.5 kb fragments which were cloned from ten well-characterized apolipoprotein[a] alleles. These ten allelic apolipoprotein[a] fragments revealed, despite the same sequence variation as previously reported, comparable and relatively weak promoter activities in HepG2 hepatocarcinoma cells. Promoter activity for the same fragment in non-liver cells and the identification of a liver cell-specific DNaseI hypersensitive site 3 kb upstream from the ATG start codon suggest that longer fragments must be used in order to analyze the transcriptional regulation of the apolipoprotein[a] gene.

Alleles↗
PubMed1994

Studies on the inheritance of repellent tolerances in Aedes aegypti.

Two laboratory strains and 6 inbred strains of Aedes aegypti were tested against deet, ethyl hexanediol, dimethyl phthalate, and Indalone. Reciprocal crosses and backcrosses of 2 inbred strains were tested against deet only. Results obtained were compatible with a quantitative genetic model in which the effects of the factors involved were multiplicative. Certain inbred strains differed significantly from cognate laboratory and/or inbred strains in tolerance to one or more test materials. Heritability in the broad sense (H2) was estimated at 0.05 for deet, 0.22 for ethyl hexanediol, 0.48 for dimethyl phthalate, and 0.51 for Indalone. Partial dominance was observed in the inheritance of tolerance to deet.

Aedes↗
PubMed1994

Monte Carlo estimation of mixed models for large complex pedigrees.

In human quantitative genetics, computational complexity restricts the current methods for estimation of mixed models that include major gene effects to data on small pedigrees. However, large complex pedigrees are not uncommon in practice. Also, large pedigrees tend to provide more information on genetic transmission and are more genetically homogeneous than a pooled sample of many nuclear families. We present a Monte Carlo method, using jointly the EM algorithm and the Gibbs sampler, for estimation of mixed models. The approach also provides a Monte Carlo estimate of the asymptotic variance-covariance matrix of the parameters. The methods are conceptually simple, easy to implement, and can handle multiple heritable/nonheritable random components. A numerical example is given to illustrate the methods.

Algorithms↗
PubMed1993

[Lipoprotein(a): a link between thrombosis and atherosclerosis?].

Lipoprotein(a) (Lp(a)) represents a class of plasma lipoproteins similar to low-density lipoprotein (LDL), but containing an unique apolipoprotein(a) with striking homology to plasminogen. Plasma Lp(a) is inherited as a quantitative genetic trait, with a continuous distribution in Caucasian populations (< 10-2000 mg/l), where high levels are associated with an increased risk of atherosclerotic disease. The physiological role of Lp(a) is unknown, and the metabolism is obscure. Plasma Lp(a) is apparently resistent to diets and drug therapy, and LDL-apheresis is currently the most effective way of reducing plasma Lp(a). However, clinical benefits of lowering plasma Lp(a) have not been demonstrated, and specific therapeutic goals cannot be recommended at present. The structural similarity between apo(a) and plasminogen has generated several experimental observations indicating a prothombogenic and proatherogenic role of Lp(a), but the exact pathophysiological mechanisms have not been determined.

Arteriosclerosis↗
PubMed1996

[Mesenteric vein infarction associated with congenital antithrombin III (ATIII) deficiency].

A venous mesenteric infarction in a 27-year-old patient is reported. This patient presented a genetic quantitative AT-III deficiency without anticoagulation therapy. Ultrasonography revealed portal vein thrombosis and laparoscopy showed mesenteric vein infarction. Laparotomy was performed mmediately and revealed segmental infarction of 60 cm of the jejunum which was resected; the portal vein was considered to be partially occluded on palpation. No strangulation or mechanical factors were identified. Immediately postoperatively the patient received therapeutic doses of heparin with AT-III concentrates to increase AT-III levels; no recurrent thrombotic episode was observed. A systematic second-look operation 24 hours postoperatively showed good bowel viability. Five days later, long-term anticoagulation with acenocoumarol was decided. Twelve days later, ultrasonography showed complete portal revascularization which was confirmed by a third surgical operation on D60.

Adult↗
PubMed1997

How frailty models can be used for evaluating longevity limits: taking advantage of an interdisciplinary approach.

In this paper we discuss an approach to the analysis of mortality and longevity limits when survival data on related individuals with and without observed covariates are available. The approach combines the ideas of demography and survival analysis with methods of quantitative genetics and genetic epidemiology. It allows us to analyze the genetic structure of frailty in the Cox-type hazard model with random effects. We demonstrate the implementation of this strategy to survival data on Danish twins. We then evaluate the resulting lower bounds for biological limits of human longevity. Finally, we discuss the limitations of this approach and directions of further research.

Aged↗
PubMed1998

Heritable non-susceptibility in an allopatric host-parasite system: Biomphalaria glabrata (Mollusca)-Echinostoma caproni (platyhelminth Digenea).

We studied the heritability of adult nonsusceptibility/susceptibility in an allopatric host-parasite system, Biomphalaria glabrata (Brazil)-Echinostoma caproni (Egypt). In this system, the fitness of the infected host is substantially reduced because of castration. Mean frequencies of susceptibility among progeny of individual susceptible or nonsusceptible parents were compared, and heritabilities of susceptibility and nonsusceptibility were calculated under a quantitative genetic model. A Monte-Carlo simulation was used to assess the significance of the heritability estimates under the hypothesis of normal standard deviation. The results showed high heritability of both nonsusceptibility (0.56) and susceptibility (0.91).

Animals↗
PubMed2006

Complex genetic interactions in a quantitative trait locus.

Whether in natural populations or between two unrelated members of a species, most phenotypic variation is quantitative. To analyze such quantitative traits, one must first map the underlying quantitative trait loci. Next, and far more difficult, one must identify the quantitative trait genes (QTGs), characterize QTG interactions, and identify the phenotypically relevant polymorphisms to determine how QTGs contribute to phenotype. In this work, we analyzed three Saccharomyces cerevisiae high-temperature growth (Htg) QTGs (MKT1, END3, and RHO2). We observed a high level of genetic interactions among QTGs and strain background. Interestingly, while the MKT1 and END3 coding polymorphisms contribute to phenotype, it is the RHO2 3'UTR polymorphisms that are phenotypically relevant. Reciprocal hemizygosity analysis of the Htg QTGs in hybrids between S288c and ten unrelated S. cerevisiae strains reveals that the contributions of the Htg QTGs are not conserved in nine other hybrids, which has implications for QTG identification by marker-trait association. Our findings demonstrate the variety and complexity of QTG contributions to phenotype, the impact of genetic background, and the value of quantitative genetic studies in S. cerevisiae.

3' Untranslated Regions↗
PubMed2002

Comparison of short tandem repeat and variable number tandem repeat genetic markers for quantitative determination of allogeneic bone marrow transplant engraftment.

Variable number tandem repeats (VNTRs) were among the first genetic markers used to quantitate bone marrow transplant engraftment. The limitations of PCR-based VNTR markers in distinguishing some donor/recipient pairs has shown the need for additional genetic markers to analyze engraftment. Short tandem repeats (STRs) provide an excellent tool for this purpose because of their high degree of polymorphism and relatively short length. We compared STR analysis results with previous VNTR results for 16 post-transplantation samples from four allogeneic bone marrow transplant patients. Previously analyzed patient samples were chosen to cover the full range of engraftment. DNA samples from each patient were analyzed in a blinded fashion. Good quantitative correlation was found between STR and VNTR results in samples from all four patients. STR markers were informative in one patient for whom PCR-based VNTR markers were not available. Correlation of VNTR and STR methods helps to validate the use of STRs for the quantitative analysis of bone marrow transplant engraftment. This study demonstrates that STR-based human identity testing kits are well suited for engraftment analysis.

Bone Marrow Transplantation↗
PubMed2006

Estimation of genetic parameters for quantitative trait loci for dairy traits in the French Holstein population.

A marker-assisted selection program (MAS) has been implemented in dairy cattle in France. The efficiency of such a selection program depends on the use of correct genetic parameters for the marked quantitative trait loci (QTL). Therefore, the objective of this study was to estimate the proportion of genetic variance explained by 4 QTL described in previous studies (these QTL are segregating on chromosomes 6, 14, 20, and 26). Genotypes for 11 markers were available for 3,974 bulls grouped within 54 sire families of the French Holstein population undergoing MAS. The parameters were estimated for 4 QTL and 5 dairy traits: milk, fat and protein yields, and fat and protein percentages. The proportion of genetic variance explained by the QTL ranged from as low as 0.03 to 0.36%. Both lack of marker informativity and poor monitoring of QTL transmission might limit the accuracy of estimation. The QTL explained a larger proportion of genetic variance for milk composition traits. The QTL on chromosome 14 and chromosomes 6 and 20 have their largest influence on fat and protein percentages, respectively. The overall proportions of genetic variance explained by the QTL were 27.0, 30.7, 24.1, 48.2, and 33.6% for milk, fat and protein yields, and fat and protein percentages, respectively. These results clearly indicated that a large part of the genetic variance is explained by a small number of QTL and that their use in MAS might be beneficial for dairy cattle breeding programs.

Animals↗
PubMed2005

[Segregation analysis of genetic system of quantitative traits in plants].

Based on the traditional polygene inheritance model of quantitative traits, the mixed major gene and polygene inheritance model was raised and considered as the general model, while pure major gene or pure polygene inheritance model being only the specific case of the general model. From the proposed theory, the segregation analysis procedure was established for studying the genetic system of quantitative traits of plants. At present this procedure can be used to evaluate the genetic effects of individual major genes (up to 2-3 major genes) and the collective genetic effects of polygenes as well as their heritability values. The present paper introduces the process of the establishment of the procedure, main achievements and application results. An example was given to illustrate the steps, methods and effectiveness of the procedure.

Crosses, Genetic↗
PubMed1996

A genetic map of quantitative trait loci for body weight in the mouse.

The genetic basis of body weight in the mouse was investigated by measuring frequency changes of microsatellite marker alleles in lines divergently selected for body weight from a base population of a cross between two inbred strains. In several regions of the genome, sharp peaks of frequency change at linked markers were detected, which suggested the presence of single genes of moderate effect, although in several other regions, significant frequency changes occurred over large portions of chromosomes. A method based on maximum likelihood was used to infer effects and map positions of quantitative trait loci (QTLs) based on genotype frequencies at one or more marker loci. Eleven QTLs with effects in the range 0.17-0.28 phenotypic standard deviations were detected; but under an additive model, these did not fully account for the observed selection response. Tests for the presence of more than one QTL in regions where there were large changes of marker allele frequency were mostly inconclusive.

Alleles↗
PubMedDate not supplied

Hypothesis testing for the genetic background of quantitative traits.

The testing of Bayesian point null hypotheses on variance component models have resulted in a tough assigmment for which no clear and generally accepted method exists. In this work we present what we believe is a succeeding approach to such a task. It is based on a simple reparameterization of the model in terms of the total variance and the proportion of the additive genetic variance with respect to it, as well as on the explicit inclusion on the prior probability of a discrete component at origin. The reparameterization was used to bypass an arbitrariness related to the impropriety of uninformative priors onto unbounded variables while the discrete component was necessary to overcome the zero probability assigned to sets of null measure by the usual continuous variable models. The method was tested against computer simulations with appealing results.

Algorithms↗