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Results for “multifactorial inheritance”

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PubMed2002

Beyond Mendel: an evolving view of human genetic disease transmission.

Methodological and conceptual advances in human genetics have led to the identification of an impressive number of human disease genes. This wealth of information has also revealed that the traditional distinction between Mendelian and complex disorders might sometimes be blurred. Genetic and mutational data on an increasing number of disorders have illustrated how phenotypic effects can result from the combined action of alleles in many genes. In this review, we discuss how an improved understanding of the genetic basis of multilocus inheritance is catalysing the transition from a segmented view of human genetic disease to a conceptual continuum between Mendelian and complex traits.

Alleles↗
PubMed2005

Studying the genetics of Hirschsprung's disease: unraveling an oligogenic disorder.

Hirschsprung's disease is characterized by the absence of ganglion cells in the myenteric and submucosal plexuses of the gastrointestinal tract. Genetic dissection was successful as nine genes and four loci for Hirschsprung's disease susceptibility were identified. Different approaches were used to find these loci such as classical linkage in large families, identity by descent mapping in an inbred kindred, candidate gene approaches based on naturally occurring mutant mice models, and finally the use of model-free linkage and association analyzes. In this study, we review the identification of genes and loci involved in the non-syndromic common form and syndromic Mendelian forms of Hirschsprung's disease. The majority of the identified genes are related to Mendelian syndromic forms of Hirschsprung's disease. The non-Mendelian inheritance of sporadic non-syndromic Hirschsprung's disease proved to be complex; involvement of multiple loci was demonstrated in a multiplicative model. We discuss the practical implications of the elucidation of genes associated with Hirschsprung's disease susceptibility for genetic counseling. Finally, we speculate on possible strategies to identify new genes for Hirschsprung's disease.

Family Health↗
PubMed1988

[The possibility of modern segregation analysis to discriminate monogenic and multifactorial types of the inheritance of traits. The reliability of models and the power of the analysis].

Using computer simulation of family data sets within segregation analysis limits the comparative research of the autosomal major locus model (MLM) and the multifactorial model (MFM) which described the basic types of inheritance of the alternative traits (affected--nonaffected) has been conducted. Robustness of models (statistical aspect) and the power of the analysis (its possibility to discriminate MLM and MFM) are tested. It is shown that permissible level of relative errors for estimated population's frequency is increased, when the values of parameters of models are increased (with decrease of sporadic cases' portion). The power of the analysis is the greatest in the field of greatest robustness of models: the higher the parameters of models, the portion of sporadic cases being low, the stronger the power of the analysis. MFM satisfactorily describes family distribution given by additive MLM. On the contrary, if the MLM corresponds to the multifactorial traits, this model is additive. It is shown that the possibility of the analysis to reject alternative model is decreased when determination of model grows down.

Genes↗
PubMed2005

Support for polygenic influences on ocular refractive error.

PURPOSE: Refractive errors, myopia, and hyperopia are common conditions requiring corrective lenses. The familial clustering of myopia has been well established. Several chromosomal regions have been linked to high myopia (12q, 17q, and 18q), to quantitative refraction among twins (3q, 4q, 8p, and 11p), and to families with moderate myopia (22q). This study examined the familial aggregation and pattern of inheritance of ocular refraction in an adult population, by using data from the Beaver Dam Eye Study. METHODS: Familial correlations were examined and segregation analysis was performed on the average refractive error measurements in the right and left eyes after adjustment for age, sex, and education. Analyses were based on 2138 individuals in 620 extended pedigrees with complete data on age, sex, education, and spherical equivalent. RESULTS: Substantial positive correlation was found between siblings (0.33), parents and offspring (0.17), and cousins (0.10) and lower correlation among avuncular pairs (0.08) after adjustment for age, sex, and years of education. The results of this segregation analysis do not support the involvement of a single major locus throughout the entire range of refractive error. However, models allowing for familial correlation, attributable in part to polygenic effects, provided a better fit to the observed data than models without a polygenic component, suggesting that several genes of modest effect may influence refractive error, possibly in conjunction with environmental factors. CONCLUSIONS: These results support the involvement of genetic factors in the etiology of refractive error and are consistent with reports of linkage to multiple regions of the genome.

Family Health↗
PubMed1981

Hereditary factors in the pathogenesis of affective illnesses.

The purpose of the study was verification of a genetic distinction between bipolar and unipolar affective illness and investigation of hypotheses concerning the mode of genetic transmission of both illnesses. The investigation demonstrated a difference between a group of 150 probands with bipolar affective illness and 50 probands with unipolar affective illness. A genetic-correlation analysis of both diseases showed that they are determined by different, partly correlated liabilities. Evaluation of the mode of inheritance suggests an multifactorial mode of inheritance of both affective illnesses: although genetic factors are of basic importance, continuously acting environmental factors also have a significant influence on the manifestation of the illness. The results suggest possible heterogeneity of both illnesses from the genetic standpoint.

Adult↗
PubMed2026

Polygenic risk score and its role in cancer susceptibility.

BACKGROUND: Polygenic risk score (PRS) has the ability to stratify inherited susceptibility to cancer and, as a complement to monogenic testing, can identify individuals at increased genetic risk even when no pathogenic variant is detected in high- or moderate-penetrance genes. It reflects the combined additive effects of a large number of low-penetrance variants across the genome, and represents a continuum of genetic susceptibility with an approximately normal distribution. Clinically relevant differences are typically observed in individuals in the highest and lowest percentiles of the PRS distribution, while relative risk gradients depend on the cancer type, the specific PRS model, and the reference population used. PRS is not a single test but rather a family of statistical models that differ in their design, predictive performance, and transferability across populations, underscoring the need for external validation and population-specific calibration of absolute risk. Broader implementation is thus still held back by differences between individual PRS models, limited transferability, and the lack of harmonized guidance on indication, reporting, and clinical decision-making. Consequently, clinical use in the European Union remains largely confined to pilot studies and local projects. Within these initiatives, PRS is most commonly applied in two main ways - either as a triage tool for intensified diagnostics or screening in higher-risk groups, or as a component of multifactorial absolute-risk models (e. g. BOADICEA/CanRisk) that integrate PRS with other risk factors such as pathogenic variants in moderate-penetrance genes (e. g. ATM or CHEK2), family history, or lifestyle factors. By refining absolute-risk estimates, PRS may shift individuals across clinical decision thresholds for more intensive surveillance and preventive strategies. AIM: This review summarizes the principles of PRS, the main sources of variability between models, and its potential applications in risk stratification and personalized cancer screening. It also addresses limitations in transferability, the need for calibration, and the currently limited evidence for improvements in hard clinical outcomes.

Humans↗
PubMed1977

[Genetic aspects of keratoconus (author's transl)].

The diverging views expressed in the literature on the inheritance of keratoconus gave us cause to examine the genetic relationships in 304 cases of keratoconus from our own clinic material. In the 22 cases (19 families) where two or more family members were affected, the genetic relationships generally indicated a multifactorial mode of inheritance, although isolated dominant or recessive variants could not be excluded. The assumption of a multifactorial inheritance is further supported by the occurrence of keratoconus in connection with various syndromes, as well as the fact that keratoconus does not only express itself in sharply defined stages, but also occurs in all possible degrees, from almost normal to the extreme.

Chromosome Aberrations↗
PubMed1979

A genetic study of febrile convulsions.

307 probands with febrile convulsions classed as the simple type (131 children) and the complicated type (176 children) were genetically analyzed. There was a tendency toward familial aggregation of febrile convulsions, and genetic involvement was suggested. The multifactorial mode of inheritance best agreed with the observations. (1) The ratio of incidence of febrile convulsions in siblings of probands in the present study (19.9%) to the incidence in the general population (2.9%), i.e., 6.85, was rather close to the expected ratio of 5.87 from the multifactorial inheritance system. (2) The incidence in siblings tended to be higher when either or both of their parents had a history of febrile convulsions. In 2-child families where the first child was affected, the incidence in the second child tended to increase in parallel with the increasing incidence in parents. (3) The incidence in siblings was higher if probands were males. (4) The heritability, when estimated by Falconer's procedure, was as high as 76%, showing that febrile convulsions are strongly genetically predisposed. These findings were more distinctly observed in the simple type than in the complicated type.

Adult↗
PubMed1993

The genetics of infantile hypertrophic pyloric stenosis. A reanalysis.

OBJECTIVE: To determine whether the existing family data for infantile hypertrophic pyloric stenosis (IHPS) are sufficient for the purposes of establishing the mode of inheritance of this condition. DESIGN: Reanalysis of the familial aggregation patterns exhibited by IHPS, using data from several published family studies. CONCLUSIONS: Due to several limitations of the available family data for IHPS, the results of this analysis should be interpreted cautiously. Within the context of these limitations, the familial recurrence pattern among monozygotic cotwins and more remote relatives of IHPS probands was found to be inconsistent with generalized single major locus inheritance. The familial recurrence pattern of IHPS is, however, compatible with multifactorial threshold inheritance or the effects of multiple interacting loci. Under a model of multiple interacting loci, no single locus can account for more than a fivefold increase in the risk to first-degree relatives of IHPS probands. In contrast to several earlier reports, this analysis does not support the existence of a maternal factor that contributes to the risk of IHPS in the offspring of affected females.

Diseases in Twins↗
PubMed2006

Genetic and environmental interactions determine seizure susceptibility in epileptic EL mice.

Gene identification has progressed rapidly for monogenic epilepsies, but complex gene-environmental interactions have hindered progress in gene identification for multifactorial epilepsies. We analyzed the role of environmental risk factors in the inheritance of multifactorial idiopathic generalized epilepsy in the EL mouse. Seizure susceptibility was evaluated in the EL (E) and seizure-resistant ABP/LeJ (A) parental mouse strains and in their AEF1 and AEF2 hybrid offspring using a handling-induced seizure test. The seizure test was administered in three environments (environments I, II and III) that differed with respect to the number of seizure tests administered (one test or four tests) and the age of the mice when tested (young or old). The inheritance of seizure susceptibility appeared dominant after repetitive seizure testing in young or old mice, but recessive after a single test in old mice. Heritability was high (0.67-0.77) in each environment. Significant quantitative trait loci (QTL) that were associated with environments I and III (repetitive testing) were found on chromosomes 2 and 9 and colocalized with previously mapped El2 and El4, respectively. The El2 QTL found in environment I associated only with female susceptibility. A novel QTL, El-N, for age-dependent predisposition to seizures was found on proximal chromosome 9 only in environment II. The findings indicate that environmental risk factors determine the genetic architecture of seizure susceptibility in EL mice and suggest that QTL for complex epilepsies should be defined in terms of the environment in which they are expressed.

Age Factors↗
PubMed2004

Triallelic inheritance: a bridge between Mendelian and multifactorial traits.

The increasing identification of disease genes is revealing a growing number of traits that fail to conform to traditional Mendelian paradigms, thereby creating new challenges to both genetic investigators and clinicians. Bardet-Biedl syndrome (BBS) is one such disorder that has helped to define 'oligogenic' inheritance, a term that implies that some diseases are not inherited as simple single-gene Mendelian disorders and yet are not classic complex traits, but rather fit a model in which mutations in a small number of genes may interact genetically to manifest the phenotype. BBS is a pleiotropic disorder characterized by postnatal obesity, post-axial polydactyly, and progressive retinal dystrophy. Eight BBS loci have been identified to date and six of these genes have been cloned. Mutation analysis of these BBS genes in a cohort of patients has led to the description of the novel phenomenon of 'triallelic inheritance', wherein families were identified in which three mutations from genes at two different BBS loci segregate with expression of the disease. Modeling the cooperative ability of alleles of different genes at distinct loci to give rise to a particular phenotype will facilitate the understanding of complex multifactorial and polygenic traits.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Inheritance of canine hip dysplasia: review of estimation methods and of heritability estimates and prospects on further developments.

Canine hip dysplasia is a long-known, widespread degenerative skeletal disease. A hereditary component of hip dysplasia was assumed early, although attempts to explain hip dysplasia with known Mendelian modes of inheritance did not sufficiently fit the data observed. Nevertheless, both recessive and dominant modes of inheritance were proposed. Later on, it was proposed that CHD was determined in a multifactorial way. Both the influence of many genes and environmental effects were assumed to affect the development of CHD. More recently, this thesis was supplemented and refined, as a major gene was detected as a cause of CHD in addition to a polygenic component. Nowadays, projects are under way with the aim to locate quantitative trait loci (QTL) significantly linked to CHD, and ultimately to develop gene tests to identify carriers of genes responsible for CHD.

Animals↗