Heritability Range Research Articles

Genetics of addiction in legal medicine and forensic investigation: SNPs variations associated with nicotine and cannabis dependence

Substance addiction is a complex chronic brain disorder, characterized by neurobiological changes leading to compulsive drug seeking and taking. Although environmental factors contribute to drug addiction, evidence showed that genetic factors with multiple genes also play a significant role. Cannabis and tobacco result as the most common widely abused substances. Epidemiological studies have strongly implicated genetics in nicotine and marijuana consuming and vulnerability to subsequent dependence, estimating the range of heritability from 34% to 78% for cannabis and approximately from 50% to 70% for nicotine. Furthermore, varying aspects of impulsive personality and principal psychiatric disorders co-occur with tobacco and cannabis dependence status. We evaluate the possibility of identifying an individual's risk probability to become an addict, based on a genotype analysis and the different possible applications in legal medicine and forensic genetics.

Genetic variation of metabolite and hormone concentration in UK Holstein-Friesian calves and the genetic relationship with economically important traits

The decline of dairy cattle fertility worldwide remains a major concern, with conception rates to first service commonly below 40%. The length and severity of negative energy balance postpartum are unfavorably correlated with fertility, suggesting that the length and severity of negative energy balance and fertility are linked via several hormones or metabolites. These compounds therefore have the potential to predict fertility at a genetic level. The addition of a predictor trait for fertility into present fertility indices would accelerate genetic gain, particularly if it was expressed before adulthood. The objective of this work was to estimate the genetic variation in several metabolites and hormones in calves, and to determine their genetic relationships with fertility and production through sire predicted transmitting abilities (PTA; sires of calves sampled). Circulating concentrations of free fatty acids (FFA), glucose, growth hormone (GH), insulin, and insulin-like growth factor 1 (IGF-1) in male and female UK Holstein-Friesian dairy calves (average age±SD; 126±12.7 d) were analyzed during 2 studies: data set 1 (n = 496 females; 1996–2001; 7 commercial dairy herds) and data set 2 (n = 326 females, n = 256 males; 2002–2006; multiple ovulation and embryo transfer breeding scheme). Univariate mixed models were fitted to the data using ASREML. Basal concentrations of FFA, glucose, GH, insulin and total IGF-1 were all moderately heritable in both sexes (heritability range±SE; 0.09±0.05 to 0.66±0.14). The sire PTA for protein percentage had significant regression coefficients and approximate genetic correlations with FFA and insulin, and the sire PTA for calving interval had significant regression coefficients and approximate genetic correlations with GH. Additive genetic variance seems responsible for a moderate proportion of the phenotypic variation in important metabolites and regulatory hormones in male and female UK Holstein-Friesian dairy calves, therefore supporting further investigation into their use as juvenile predictors for fertility in the mature female.

Epidemiology, Heritability, and Genetic Linkage of C-Reactive Protein in African Americans (from the Jackson Heart Study)

C-reactive protein (CRP) has been studied largely in white non-Hispanic cohorts. There is limited information on CRP's range of values, heritability, and relation to cardiovascular disease risk factors in African Americans. The aim of this study was to evaluate the distribution, clinical correlates, heritability, and genetic linkage of log-transformed CRP in participants in the middle-aged to elderly African American cohort in the community-based Jackson Heart Study. The distribution and correlates of CRP were analyzed for the entire study cohort who underwent the first examination (2001 to 2004). Heritability was estimated for the family cohort nested within the larger Jackson Heart Study (246 families, n = 1,317). The relation between CRP and cardiovascular disease risk factors was tested with multivariable stepwise regression analyses. Heritability was estimated using a variance-components method. Linkage analysis was performed using the multipoint variance-components approach. The study sample consisted of 4,919 participants (mean age 55 +/- 13 years, 63% women); the median CRP concentration was 2.7 mg/L. In stepwise models, traditional risk factors explained 23.8% of CRP's variability, with body mass index (partial R(2) = 13.6%) explaining 57.1% of the variability of CRP due to traditional risk factors. The heritability of CRP (adjusted for age, gender, and body mass index) was 0.45. The strongest linkage evidence for CRP was observed on chromosome 11 (11p13 to 11p11.2), with a logarithm of odds score of 2.72. In conclusion, in this large population-based cohort of African Americans, circulating CRP concentration was heritable and associated with several traditional cardiovascular risk factors, particularly body mass index.

The contribution of social effects to heritable variation in finishing traits of domestic pigs (Sus scrofa).

Social interactions among individuals are ubiquitous both in animals and in plants, and in natural as well as domestic populations. These interactions affect both the direction and the magnitude of responses to selection and are a key factor in evolutionary success of species and in the design of breeding schemes in agriculture. At present, however, very little is known of the contribution of social effects to heritable variance in trait values. Here we present estimates of the direct and social genetic variance in growth rate, feed intake, back fat thickness, and muscle depth in a population of 14,032 domestic pigs with known pedigree. Results show that social effects contribute the vast majority of heritable variance in growth rate and feed intake in this population. Total heritable variance expressed relative to phenotypic variance was 71% for growth rate and 70% for feed intake. These values clearly exceed the usual range of heritability for those traits. Back fat thickness and muscle depth showed no heritable variance due to social effects. Our results suggest that genetic improvement in agriculture can be substantially advanced by redirecting breeding schemes, so as to capture heritable variance due to social effects.

Bivariate Genetic Modeling of Cardiovascular Stress Reactivity: Does Stress Uncover Genetic Variance?

To test the existence of gene-by-stress interaction by assessing cardiovascular stress reactivity in monozygotic and dizygotic twins. We studied 160 adolescent (mean age 16.7 +/- 2.0 years; range 13-22 years) and 212 middle-aged twin pairs (mean age 44.2 +/- 6.7 years; range 34-63 years). Systolic (SBP) and diastolic (DBP) blood pressure, heart rate (HR), pre-ejection period (PEP), and respiratory sinus arrhythmia (RSA) were measured at rest and during a choice reaction time and a mental arithmetic task. We used a bivariate analysis of the resting and mean stress levels to test for gene-by-stress interaction, which can be caused by the emergence of new genetic variance specific to stress or by stress-induced amplification of the existing genetic variance at rest. Genetic factors significantly contributed to individual differences in resting SBP, DBP, HR, PEP, and RSA levels in the adolescent (heritability range 0.31-0.70) and middle-aged (heritability range 0.32-0.64) cohorts. The effect of these genetic factors was amplified by stress for all variables in the adolescent cohort, and for SBP in the middle-aged cohort. In addition, stress-specific genetic variation emerged for HR in both cohorts and for PEP and SBP in the adolescent cohort. Heritability of stress levels of SBP, DBP, HR, PEP, and RSA ranged from 0.54 to 0.74 in the adolescents and from 0.44 to 0.64 in the middle-aged cohort. Stress uncovers genetic variance in BP, HR, and cardiac sympathovagal balance through the emergence of new stress-specific genetic effects and the amplification of existing genetic effects that also affect the resting values.

Genetic variability and path analysis in bellary onion (Allium cepa var. cepa L.) for storage losses

Sixty-two genotypes of onion were collected and evaluated. The range, phenotypic and genotypic coefficients of variation, heritability and genetic advance for the thirteen characters were studied. In storage loss, higher estimates of genotypic and phenotypic coefficients of variation were recorded for bulb weight, reducing sugars, non-reducing sugars, total sugars, total loss and sulphur content. For storage loss, bulb weight, total loss, reducing sugars and sulphur content the higher heritability coupled with high genetic advance were registered. Path co-efficient analysis, indicted that the reducing sugars, protein and total loss had the strongest positive direct effect on storage loss.

The impact of differential success of somatic embryogenesis on the outcome of clonal forestry programs. I. Initial comparison under multitrait selection

A breeding program where clones or clone mixtures are deployed through somatic embryogenesis of superior genotypes produced from elite-parent crosses was evaluated by simulation. A recurrent-selection scheme for general combining ability was considered with a breeding population size of 100 individuals. The population was assortatively pair-crossed with offspring cloned in a progeny test to facilitate forward selection of the next generation. Apart from crosses for the population advancement, "elite" crosses were made among 10 top-ranking individuals in each generation. These crosses differed in their propensity to produce somatic embryos (defined as induction success rate); the impact of this variable propensity on genetic response for two traits in selected 10-clone deployment mixtures was evaluated. The two traits considered in this study can be regarded as "productivity" and "quality". The results revealed that variation in success of clonal propagation does not necessarily lead to a reduction in potential genetic gains from selected clonal mixtures. This can be explained by the relatively small variation that exists among elite crosses, as opposed to large within-family variation. This large within-family variation provides ample potential for selecting superior offspring genotypes, even though they may have not originated from crosses among the very best of the elite parents. This conclusion holds for a range of heritability, correlations between traits, and their relative economic importance.

Positive Assortative Mating With Family Size as a Function of Predicted Parental Breeding Values

While other investigations have described benefits of positive assortative mating (PAM) for forest tree breeding, the allocation of resources among mates in these studies was either equal or varied, using schemes corresponding only to parental rank (i.e., more resources invested in higher-ranking parents). In this simulation study, family sizes were proportional to predicted midparent BLUP values. The distribution of midparent BLUP values was standardized by a constant, which was varied to study the range of distributions of family size. Redistributing progenies from lower- to higher-ranking families to a point where an equal number of progenies were still selected out of each family to the next generation caused minimal change in group coancestry and inbreeding in the breeding population (BP), while the additive genetic response and variance in the BP were both greatly enhanced. This generated additional genetic gains for forest plantations by selecting more superior genotypes from the BP (compared to PAM with equal family sizes) for production of improved regeneration materials. These conclusions were verified for a range of heritability under a polygenic model and under a mixed-inheritance model with a QTL contributing to the trait variation.

Site and gender specificity of inheritance of bone mineral density.

Differences in genetic control of BMD by skeletal sites and genders were examined by complex segregation analysis in 816 members of 147 families with probands with extreme low BMD. Spine BMD correlated more strongly in male-male comparisons and hip BMD in female-female comparisons, consistent with gender- and site-specificity of BMD heritability. Evidence from studies in animals and humans suggests that the genetic control of bone mineral density (BMD) may differ at different skeletal sites and between genders. This question has important implications for the design and interpretation of genetic studies of osteoporosis. We examined the genetic profile of 147 families with 816 individuals recruited through probands with extreme low BMD (T-score < -2.5, Z-score < -2.0). Complex segregation analysis was performed using the Pedigree Analysis Package. BMD was measured by DXA at both lumbar spine (L1-L4) and femoral neck. Complex segregation analysis excluded purely monogenic and environmental models of segregation of lumbar spine and femoral neck BMD in these families. Pure polygenic models were excluded at the lumbar spine when menopausal status was considered as a covariate, but not at the femoral neck. Mendelian models with a residual polygenic component were not excluded. These models were consistent with the presence of a rare Mendelian genotype of prevalence 3-19%, causing high BMD at the hip and spine in these families, with additional polygenic effects. Total heritability range at the lumbar spine was 61-67% and at the femoral neck was 44-67%. Significant differences in correlation of femoral neck and lumbar spine BMD were observed between male and female relative pairs, with male-male comparisons exhibiting stronger lumbar spine BMD correlation than femoral neck, and female-female comparisons having greater femoral neck BMD correlation than lumbar spine. These findings remained true for parent-offspring correlations when menopausal status was taken into account. The recurrence risk ratio for siblings of probands of a Z-score < -2.0 was 5.4 at the lumbar spine and 5.9 at the femoral neck. These findings support gender- and site-specificity of the inheritance of BMD. These results should be considered in the design and interpretation of genetic studies of osteoporosis.

Evidence for genetic mediation of executive control: a study of aging male twins.

The objective of this study was to investigate the genetic and environmental influences on indexes of executive control in elderly male twins (members of the National Heart, Lung, and Blood Institute Twin Study). Multivariate genetic modeling was applied to performance on four tests: Digit Symbol Substitution, color--word interference, Trail Making B, and verbal fluency. After exclusion of individuals with a positive stroke history, data were available for 80 monozygotic and 78 dizygotic twin pairs of ages 69--80 years. Performance on all measures was adjusted for age and education. Significant genetic and environmental influences to performance on each measure of executive control were identified (range of heritability = 34%--68%). Multivariate analyses revealed that a model with a latent executive control factor most adequately fit the observed covariances on test performance, chi(2)(58, N = 316) = 69.7, p =.14. The shared executive control factor had a heritability of 79% and accounted for 10%--56% of the genetic variance in performance on each of the four tests. Of the 4 tests examined in this analysis, Digit Symbol Substitution appeared to be the marker of executive control with the largest genetic component, whereas verbal fluency stood out as displaying a pattern of genetic and environmental influences distinct from the other 3 measures.

Sample test-day heritability estimates for somatic cell score for Hungarian Holstein- Friesian crossbreds

There have been many studies of genetic variance in somatic cell score (SCS). Reported estimates of heritability (h2) range from 0.02 to 0.16, the lowest h2 obtained in the 1st parity and increased in the later lactations (Mrode and Swanson 1996). The objective of the present study was to examine the effect of introducing Holstein-Friesian genes in the Hungarian native breed on the inheritance of sample test-days SCS.

Zusammenhang zwischen Parametern des Glukosetoleranztestes bei Jungbullen und deren Nachkommenzuchtwert

Abstract. Title of the paper: Relationships between parameters of the glucose tolerance test by young sires and estimated their breeding values A high milk Performance connected to a sound health regarding metabolism and a sufficient fertility in dairy cows depends on a well balanced distribution of energy in body. The terms "type of tumover" and "type of deposition" embody two extremes of food energy preferably for milk production or for body composition. Insulin plays an outstanding role based on its central position in energetic metabolism. The function of insulin may be recorded by means of the intravenous glucose tolerance test (GTT). The reaction of insulin and glucose was investigated after infusion of 1 g Glucose/kg075 because of the probable genetic determination of the reactive ability. The coefficients of heritability range from h2 = 0.16 + 0.10 to h2 = 0.28 ± 0.16. Investigating 28 sires the correlation coefficients amount to r = 0.5 for parameters of gluccose tolerance test and estimated breeding values which is closer than those between pedigree breeding value and glucose tolerance test.This is expecting additional Information for young sires before the insert of the test.

Familial resemblance in fatness and fat distribution.

The purpose of the study was to estimate the degree of familial resemblance in anthropometric indicators of fatness and fat distribution. The sample consisted of 327 Caucasian participants from 102 nuclear families. Indicators of fatness included the body mass index (BMI), the sum of six skinfolds (SF6: triceps + biceps + medial calf + subscapular + suprailiac + abdominal), and waist circumference (WAIST), while indicators of fat distribution included WAIST adjusted for BMI (WAIST(ADJ)), the trunk-to-extremity skinfold ratio, adjusted for SF6 (TER(ADJ)), and the first principal component of skinfolds, adjusted for the mean skinfold of the individual (PC1). A general familial correlation model was fit to the data, and a series of nested reduced models were also fit so as to test hypotheses about familial resemblance. The hypothesis of no familial resemblance (all familial correlations are zero) was rejected for all phenotypes, indicating that fatness and fat distribution aggregate within families. For the three indicators of fatness (BMI, SF6, and WAIST), the sibling and parent-offspring correlations were significant. Further, there were no sex or generation differences in the familial correlations. For the three indicators of fat distribution (TER(ADJ), WAIST(ADJ), and PC1), there was no parent-offspring resemblance; sibling resemblance was significant for TER(ADJ) and PC1. Further, spouse resemblance was not significant for WAIST(ADJ), but was for TER(ADJ) and PC1. For both WAIST(ADJ) and PC1 there were significant sex differences in the familial correlations. A combination of models including no sex or generation differences and no spouse resemblance was the most parsimonious model for BMI, SF6, and TER(ADJ). The environmental model (all correlations equal) was the most parsimonious for WAIST, the model of no sibling resemblance was the most parsimonious for WAIST(ADJ), and the model of no spousal resemblance was the most parsimonious for PC1. Estimates of maximal heritability range from 46-60% for fatness and from 29-48% for fat distribution, independent of overall fatness, suggesting that in this sample the heritability of fatness is greater than that for fat distribution. Further, the pattern of correlations, which generally includes no spousal resemblance but significant parent-offspring and sibling correlations, suggests the role of genes in explaining at least part of the heritability. Am. J. Hum. Biol. 12:395-404, 2000. Copyright 2000 Wiley-Liss, Inc.

Quantitative genetics of sex ratio traits in the parasitic wasp, Nasonia vitripennis.

We detected significant parent-offspring regressions for the first sex ratio (the sex ratio produced by a female in a fresh host) and the second sex ratio (the sex ratio produced by a female in a previously parasitized host) in the parasitic wasp, Nasonia vitripennis. For both traits, estimates of the narrow-sense heritability range from approximately 0.05 to approximately 0.15 (depending on how the data are analyzed). The study population was derived from isofemale strains created from wasps captured in a single bird nest. The same population exhibited no significant parent-offspring regression for the brood sizes associated with the first and second sex ratios. There may be a significant negative parent-offspring regression for diapause proportion in the first sex ratio broods. The estimates of the genetic correlations between first and second sex ratios are positive although almost all are not significantly different from 0.0. To our knowledge, this study is the first "fine-scale" analysis of genetic variation for sex ratio traits in any species of insect. Such studies are an essential part of the assessment of the validity of claims that sex ratio traits are locally optimal.

Genetic specification of life span and self-fertility in recombinant-inbred strains of Caenorhabditis elegans

The genetic basis of life-span and age-specific fertility has been analysed using recombinant-inbred strains of the nematode Caenorhabditis elegans. Estimates of narrow-sense heritability range from 0.05 to 0.36 for life span and from 0.36 to 0.49 for total self-fertility. Positive phenotypic and genetic correlations for life span and total fertility were also observed, although in most cases the correlations were not significant. In general, age-specific hermaphrodite fertility was positively correlated with fertility on contiguous days but was negatively correlated with fertility on more distant days. We estimate that a minimum of two to three genes specify each of these traits in this genetic background. Three single-gene markers were used to generate strain distribution patterns, and two of these were found to be linked with loci that specify life span and/or fertility. We also saw evidence for a significant environmental component affecting self-fertility.

Effects of selective return on estimates of heritability for body mass index in the national heart, lung, and blood institute twin study

In the National Heart, Lung, and Blood Institute Twin Study, body mass index (BMI) was studied at military induction and at three subsequent examinations spanning five decades in a cohort of white, male World War II veterans. At military induction (1940s) and again at the first clinical examination of this study (1969-1973), there was close agreement of three commonly used estimates of heritability (range 0.72 to 0.80), and no evidence of a difference in total variance of BMI between the zygosities. However, at the last two examinations (1980s), the total variance in dizygotic (DZ) twins was significantly greater than that of monozygotic (MZ) twins (P less than 0.01) and these same heritability estimates varied widely. The among-pair estimate of heritability fell to unrealistic negative values, the within-pair estimate rose to values of 1.0 or greater, and the intraclass correlation coefficient estimate was slightly lower than in the entire cohort at baseline. The cause of the unequal zygosity total variance appears to have been nonparticipation at later examinations of MZ twins with extreme values of BMI, with no evidence of a similar selection process influencing DZ twins. This selection process biased the three estimates of heritability, making it difficult to determine which estimate is the most appropriate. Despite these biases, it remains clear that genetic factors contribute substantially to BMI in this population.

Design Efficiencies with Planned and Unplanned Unbalance for Estimating Heritability in Forestry

Abstract Design efficiencies are evaluated for the estimation of heritability in unbalanced designs using Modified Maximum Likelihood estimation. Assuming knowledge of the variance components, the variance of the estimate of heritability is calculated. The effects of block size, plot size, family size, variance of family size, and total number of observations on design efficiency are examined across the range of heritability and under 100%, 90%, 80%, and 60% survival. The implications of each of these design factors are discussed. There is no uniformly best design for estimating heritability; the most efficient design is a function of the heritability. For. Sci. 35(3):801-815.

Inheritance of three agronomic characters in cowpea (Vigna unguiculata L.)

The genetics of three agronomic characters are studied in seven cowpea crosses. Seed size. In crosses between large and small seeded parents, small seeds appear to be partially dominant. There is transgressive segregation for small seeds. Broad sense estimates of heritability range from 49% to 82%. Correlation and regression coefficients between F1, F2, F3 and their respective progenies indicate that selection for seed size will be very effective starting from the F2 generation. Number of seeds. Fewer number of seeds is partially dominant over larger number of seeds. There is transgressive segregation for fewer number of seeds. Estimates of broad sense heritability range from 16 to 73%. Pod length. Short pods are partially dominant over long pods. In one cross there is transgressive segregation for both short and long pods. Estimates of broad sense heritability range from 46 to 67%.

Genetic Variability and Path Coefficient Analysis of Components of Ragi (Eleusine Coracana)

SummaryThe range, mean, genotypic and phenotypic coefficients of variation, heritability and genetic advance for various characters, of forty-seven varieties of ragi (Eleusine coracana) showed a wide range of variation and highly significant varietal differences. The genetic advance was highest for yield of straw and genotypic coefficients were higher than phenotypic coefficients for most characters. Path coefficient analysis indicated that the number of productive tillers and grain weight of main ears were the major components for seed yield.