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International Journal of Molecular... Mar 2023Inbreeding is the crossing of closely related individuals in nature or a plantation or self-pollinating plants, which produces plants with high homozygosity. This... (Review)
Review
Inbreeding is the crossing of closely related individuals in nature or a plantation or self-pollinating plants, which produces plants with high homozygosity. This process can reduce genetic diversity in the offspring and decrease heterozygosity, whereas inbred depression (ID) can often reduce viability. Inbred depression is common in plants and animals and has played a significant role in evolution. In the review, we aim to show that inbreeding can, through the action of epigenetic mechanisms, affect gene expression, resulting in changes in the metabolism and phenotype of organisms. This is particularly important in plant breeding because epigenetic profiles can be linked to the deterioration or improvement of agriculturally important characteristics.
Topics: Animals; Inbreeding; Plant Breeding; Epigenesis, Genetic; Plants; Heterozygote
PubMed: 36982483
DOI: 10.3390/ijms24065407 -
Trends in Genetics : TIG Jun 2018Unbiased allele transmission into progeny is a fundamental genetic concept canonized as Mendel's Law of Segregation. Not all alleles, however, abide by the law. Killer... (Review)
Review
Unbiased allele transmission into progeny is a fundamental genetic concept canonized as Mendel's Law of Segregation. Not all alleles, however, abide by the law. Killer meiotic drivers are ultra-selfish DNA sequences that are transmitted into more than half (sometimes all) of the meiotic products generated by a heterozygote. As their name implies, these loci gain a transmission advantage in heterozygotes by destroying otherwise viable meiotic products that do not inherit the driver. We review and classify killer meiotic drive genes across a wide spectrum of eukaryotes. We discuss how analyses of these ultra-selfish genes can lead to greater insight into the mechanisms of gametogenesis and the causes of infertility.
Topics: Alleles; Chromosome Segregation; Eukaryota; Genetics; Heterozygote; Meiosis
PubMed: 29499907
DOI: 10.1016/j.tig.2018.02.003 -
Archives of Disease in Childhood May 1977
Topics: Cystic Fibrosis; Gene Frequency; Genetic Diseases, Inborn; Heterozygote; Humans; Selection, Genetic
PubMed: 869563
DOI: 10.1136/adc.52.5.343 -
Nature Genetics May 2019In numerous applications, from working with animal models to mapping the genetic basis of human disease susceptibility, knowing whether a single disrupting mutation in a... (Review)
Review
In numerous applications, from working with animal models to mapping the genetic basis of human disease susceptibility, knowing whether a single disrupting mutation in a gene is likely to be deleterious is useful. With this goal in mind, a number of measures have been developed to identify genes in which protein-truncating variants (PTVs), or other types of mutations, are absent or kept at very low frequency in large population samples-genes that appear 'intolerant' to mutation. One measure in particular, the probability of being loss-of-function intolerant (pLI), has been widely adopted. This measure was designed to classify genes into three categories, null, recessive and haploinsufficient, on the basis of the contrast between observed and expected numbers of PTVs. Such population-genetic approaches can be useful in many applications. As we clarify, however, they reflect the strength of selection acting on heterozygotes and not dominance or haploinsufficiency.
Topics: Animals; Gene Frequency; Genes, Recessive; Genetic Drift; Genetics, Population; Haploinsufficiency; Heterozygote; Humans; Loss of Function Mutation; Models, Genetic; Mutation; Selection, Genetic
PubMed: 30962618
DOI: 10.1038/s41588-019-0383-1 -
Journal of Mathematical Biology Dec 2020In this study, we consider admixed populations through their expected heterozygosity, a measure of genetic diversity. A population is termed admixed if its members...
In this study, we consider admixed populations through their expected heterozygosity, a measure of genetic diversity. A population is termed admixed if its members possess recent ancestry from two or more separate sources. As a result of the fusion of source populations with different genetic variants, admixed populations can exhibit high levels of genetic diversity, reflecting contributions of their multiple ancestral groups. For a model of an admixed population derived from K source populations, we obtain a relationship between its heterozygosity and its proportions of admixture from the various source populations. We show that the heterozygosity of the admixed population is at least as great as that of the least heterozygous source population, and that it potentially exceeds the heterozygosities of all of the source populations. The admixture proportions that maximize the heterozygosity possible for an admixed population formed from a specified set of source populations are also obtained under specific conditions. We examine the special case of [Formula: see text] source populations in detail, characterizing the maximal admixture in terms of the heterozygosities of the two source populations and the value of [Formula: see text] between them. In this case, the heterozygosity of the admixed population exceeds the maximal heterozygosity of the source groups if the divergence between them, measured by [Formula: see text], is large enough, namely above a certain bound that is a function of the heterozygosities of the source groups. We present applications to simulated data as well as to data from human admixture scenarios, providing results useful for interpreting the properties of genetic variability in admixed populations.
Topics: Computer Simulation; Genetics, Population; Heterozygote; Humans; Models, Biological
PubMed: 33034736
DOI: 10.1007/s00285-020-01531-9 -
Current Opinion in Plant Biology Apr 2017Since the introduction of next generation sequencing, plant genome assembly projects do not need to rely on dedicated research facilities or community-wide consortia... (Review)
Review
Since the introduction of next generation sequencing, plant genome assembly projects do not need to rely on dedicated research facilities or community-wide consortia anymore, even individual research groups can sequence and assemble the genomes they are interested in. However, such assemblies are typically not based on the entire breadth of genomic technologies including genetic and physical maps and their contiguities tend to be low compared to the full-length gold standard reference sequences. Recently emerging third generation genomic technologies like long-read sequencing or optical mapping promise to bridge this quality gap and enable simple and cost-effective solutions for chromosomal-level assemblies.
Topics: Animals; Genome, Plant; Genomics; Heterozygote; Polyploidy; Sequence Analysis, DNA
PubMed: 28231512
DOI: 10.1016/j.pbi.2017.02.002 -
Journal of Cystic Fibrosis : Official... Sep 2016
Topics: Asthma; Cystic Fibrosis; Heterozygote; Humans
PubMed: 27451013
DOI: 10.1016/j.jcf.2016.07.003 -
Central European Journal of Public... Mar 2017The paper presents the results od 22-year study of screening and follow-up of haemoglobinopathies in Slovakia, an overview of genetic mutations, the coincidence with...
BACKGROUND
The paper presents the results od 22-year study of screening and follow-up of haemoglobinopathies in Slovakia, an overview of genetic mutations, the coincidence with hereditary haemochromatosis mutations, and the procedure in genetic councelling.
METHODS
Between 1993-2015, in three centres in Bratislava and in one centre in Kosice, carriers of beta-thalassaemic genes or other haemoglobinopathies were searched for. Diagnosis was performed by haematologists, whereby the family history was evaluated, together with the overall clinical condition, blood count and blood smear, iron and haemolysis parameters, mutations of hereditary haemochromatosis, and haemoglobin electrophoresis testing. In the last years the haemoglobin division also examined by high performance liquid chromatography (HPLC).
RESULTS
A clinical suspicion of the heterozygous form of beta-thalassaemia or other haemoglobinopathies was documented in 554 patients. Of them 32 (5.8%) were foreigners. 213 (38.45%) patients were genetically examined. In 190 (33.93%) of them heterozygote beta-thalassaemia was confirmed. The most frequent mutations were IVS 1.110 (33.15%), IVS 2.1 (33.15%), and IVS 1.6 (14.7%). Evidence of haemoglobin S (heterozygote sickle cell anaemia) was also notable in two non-relative children, whose fathers were of African origin, and one patient from Ghana. One female patient was followed up for haemoglobin Santa Ana (non-stabile haemoglobin previously diagnosed as mutation de novo). In our group, we took care of pregnant patients with haemoglobinopathies.
CONCLUSIONS
The study showed that there is a higher number of heterozygotes for beta-thalassaemia and rarely haemoglobinopathies in Slovakia. Over the past years, we have recorded an increase number of foreigners coming to our country. It is necessary to continue in search of pathological gene carriers to avoid serious forms of haemoglobinopathies.
Topics: Adult; Female; Genetic Counseling; Hemoglobinopathies; Heterozygote; Humans; Mutation; Pregnancy; Slovakia
PubMed: 28399358
DOI: 10.21101/cejph.a4471 -
Philosophical Transactions of the Royal... Mar 2022The distribution of genetic diversity over geographical space has long been investigated in population genetics and serves as a useful tool to understand evolution and...
The distribution of genetic diversity over geographical space has long been investigated in population genetics and serves as a useful tool to understand evolution and history of populations. Within some species or across regions of contact between two species, there are instances where there is no apparent ecological determinant of sharp changes in allele frequencies or divergence. To further understand these patterns of spatial genetic structure and potential species divergence, we model the establishment of clines that occur due to the surfing of underdominant alleles during range expansions. We provide analytical approximations for the fixation probability of underdominant alleles at expansion fronts and demonstrate that gene surfing can lead to clines in one-dimensional range expansions. We extend these results to multiple loci via a mixture of analytical theory and individual-based simulations. We study the interaction between the strength of selection against heterozygotes, migration rates, and local recombination rates on the formation of stable hybrid zones. Clines created by surfing at different loci can attract each other and align after expansion, if they are sufficiently close in space and in terms of recombination distance. Our findings suggest that range expansions can set the stage for parapatric speciation due to the alignment of multiple selective clines, even in the absence of ecologically divergent selection. This article is part of the theme issue 'Species' ranges in the face of changing environments (part I)'.
Topics: Alleles; Gene Frequency; Genetics, Population; Heterozygote; Models, Genetic
PubMed: 35067089
DOI: 10.1098/rstb.2021.0006 -
G3 (Bethesda, Md.) Jan 2017Assortative mating has been suggested to result in an increase in heritability and additive genetic variance through an increase in linkage disequilibrium. The impact of...
Assortative mating has been suggested to result in an increase in heritability and additive genetic variance through an increase in linkage disequilibrium. The impact of assortative mating on linkage disequilibrium was explicitly examined for the two-locus model of Wright (1921) and two selective assortative mating models. For the Wright (1921) model, when the proportion of assortative mating was high, positive linkage disequilibrium was generated. However, when the proportion of assortative mating was similar to that found in some studies, the amount of linkage disequilibrium was quite low. In addition, the amount of linkage disequilibrium was independent of the level of recombination. For two selective assortative models, the amount of linkage disequilibrium was a function of the amount of recombination. For these models, the linkage disequilibrium generated was negative mainly because repulsion heterozygotes were favored over coupling heterozygotes. From these findings, the impact of assortative mating on linkage disequilibrium, and consequently heritability and additive genetic variance, appears to be small and model-specific.
Topics: Animals; Genotype; Heterozygote; Humans; Linkage Disequilibrium; Models, Genetic; Recombination, Genetic; Reproduction; Selection, Genetic; Sexual Behavior, Animal
PubMed: 27784755
DOI: 10.1534/g3.116.034967