Heterozygosity, Loss of

2014 ◽  
Author(s):  
Hawkins B. De France ◽  
Elaine A. Ostrander
Keyword(s):  
Heterozygosity Loss

scholarly journals Heterozygosity Loss at 22q and Lack of INI1 Gene Mutation in Gastrointestinal Stromal Tumor

Pathobiology ◽  
2011 ◽  
Vol 78 (3) ◽  
pp. 132-139 ◽  
Author(s):  
Hidetaka Yamamoto ◽  
Kenichi Kohashi ◽  
Masazumi Tsuneyoshi ◽  
Yoshinao Oda
Keyword(s):  
Gastrointestinal Stromal Tumor ◽  
Gene Mutation ◽  
Stromal Tumor ◽  
Heterozygosity Loss

scholarly journals Formation of a hyperdiploid karyotype in childhood acute lymphoblastic leukemia [see comments]

Blood ◽  
1992 ◽  
Vol 80 (1) ◽  
pp. 203-208 ◽  
Author(s):  
N Onodera ◽  
NR McCabe ◽  
CM Rubin
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Loss Of Heterozygosity ◽  
Molecular Basis ◽  
Lymphoblastic Leukemia ◽  
Chromosome 21 ◽  
Mechanism Of Formation ◽  
Length Polymorphisms ◽  
Equal Dose ◽  
Heterozygosity Loss ◽  
Haploid Karyotype

Hyperdiploidy with greater than or equal to 50 chromosomes is a frequent and distinct karyotypic pattern in the malignant cells of children with acute lymphoblastic leukemia. To understand better the mechanism of formation of the hyperdiploid karyotype, we studied 15 patients using 20 DNA probes that detect restriction fragment length polymorphisms. We first examined disomic chromosomes for loss of heterozygosity. Two patients had widespread loss of heterozygosity on all informative disomic chromosomes, and represent cases of near- haploid leukemia in which the chromosomes doubled. One other patient had loss of heterozygosity limited to chromosome 3; in this patient all of seven other informative disomic chromosomes retained heterozygosity. Loss of heterozygosity was not detected in the remaining 12 patients on a total of 87 informative disomic chromosomes. We then examined tetrasomic chromosomes for parental dosage. Of the 13 patients in whom widespread loss of heterozygosity was not present, 11 patients had tetrasomy 21; 10 of 11 (91%) had an equal dose of maternal and paternal alleles on chromosome 21 and only 1 of 11 (9%) had an unequal dose of parental alleles in a 3:1 ratio. These results suggest that the hyperdiploid karyotype usually arises by simultaneous gain of chromosomes from a diploid karyotype during a single abnormal cell division, and occasionally by doubling of chromosomes from a near- haploid karyotype. The hyperdiploidy in cases without widespread loss of heterozygosity is not caused by stepwise or sequential gains from a diploid karyotype or by losses from a tetraploid karyotype; the former should result in a 3:1 parental dosage for 67% of tetrasomic chromosomes (9% observed) and the latter should result in loss of heterozygosity for 33% of disomic chromosomes (1% observed). Additional studies of the molecular basis for this leukemia subtype are warranted.

scholarly journals IUCN Red List and the value of integrating genetics

2020 ◽  
Vol 21 (5) ◽  
pp. 795-801 ◽  
Author(s):  
Brittany A. Garner ◽  
Sean Hoban ◽  
Gordon Luikart
Keyword(s):  
Endangered Species ◽  
Extinction Risk ◽  
Species Traits ◽  
Iucn Red List ◽  
Red List ◽  
Effective Population ◽  
Mature Adults ◽  
Heterozygosity Loss ◽  
Species Lists ◽  
Explicit Consideration

Abstract Many species on endangered species lists such as the IUCN Red List (RL) are categorized using demographic factors such as numbers of mature individuals. Genetic factors are not currently used in the RL even though their explicit consideration, including effective population size (Ne) and expected heterozygosity-loss (H-loss), could improve the assessment of extinction risk. Here, we consider the estimation of Ne and H-loss in the context of RL species. First, we investigate the reporting of number of mature individuals for RL Endangered species, which is needed to estimate Ne and H-loss. We found 77% of species assessments studied here did not report methods used to estimate the number of mature adults, and that these assessments rarely report other important determinants of Ne (e.g., sex ratio, variance in family size). We therefore applied common rules of thumb to estimate Ne, and found that Ne was likely < 50 for at least 25% of the 170 RL Endangered species studied here. We also estimated mean expected H-loss for these species over the next 100 years, and found it to be 9–29%. These estimates of high H-loss and low Ne suggest that some species listed as Endangered likely warrant listing as Critically Endangered if genetic considerations were included. We recommend that RL and other assessment frameworks (i) report methods used for estimating the number of mature adults, (ii) include standardized information on species traits that influence Ne to facilitate Ne estimation, and (iii) consider using concepts like Ne and heterozygosity-loss in risk assessments.

scholarly journals Formation of a hyperdiploid karyotype in childhood acute lymphoblastic leukemia [see comments]

Blood ◽  
1992 ◽  
Vol 80 (1) ◽  
pp. 203-208 ◽  
Author(s):  
N Onodera ◽  
NR McCabe ◽  
CM Rubin
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Loss Of Heterozygosity ◽  
Molecular Basis ◽  
Lymphoblastic Leukemia ◽  
Chromosome 21 ◽  
Mechanism Of Formation ◽  
Length Polymorphisms ◽  
Equal Dose ◽  
Heterozygosity Loss ◽  
Haploid Karyotype

Abstract Hyperdiploidy with greater than or equal to 50 chromosomes is a frequent and distinct karyotypic pattern in the malignant cells of children with acute lymphoblastic leukemia. To understand better the mechanism of formation of the hyperdiploid karyotype, we studied 15 patients using 20 DNA probes that detect restriction fragment length polymorphisms. We first examined disomic chromosomes for loss of heterozygosity. Two patients had widespread loss of heterozygosity on all informative disomic chromosomes, and represent cases of near- haploid leukemia in which the chromosomes doubled. One other patient had loss of heterozygosity limited to chromosome 3; in this patient all of seven other informative disomic chromosomes retained heterozygosity. Loss of heterozygosity was not detected in the remaining 12 patients on a total of 87 informative disomic chromosomes. We then examined tetrasomic chromosomes for parental dosage. Of the 13 patients in whom widespread loss of heterozygosity was not present, 11 patients had tetrasomy 21; 10 of 11 (91%) had an equal dose of maternal and paternal alleles on chromosome 21 and only 1 of 11 (9%) had an unequal dose of parental alleles in a 3:1 ratio. These results suggest that the hyperdiploid karyotype usually arises by simultaneous gain of chromosomes from a diploid karyotype during a single abnormal cell division, and occasionally by doubling of chromosomes from a near- haploid karyotype. The hyperdiploidy in cases without widespread loss of heterozygosity is not caused by stepwise or sequential gains from a diploid karyotype or by losses from a tetraploid karyotype; the former should result in a 3:1 parental dosage for 67% of tetrasomic chromosomes (9% observed) and the latter should result in loss of heterozygosity for 33% of disomic chromosomes (1% observed). Additional studies of the molecular basis for this leukemia subtype are warranted.

16q heterozygosity loss in Wilms» tumour in children and its clinical importance

2000 ◽  
Vol 26 (1) ◽  
pp. 61-66 ◽  
Author(s):  
G Skotnicka-Klonowicz ◽  
P Rieske ◽  
J Bartkowiak ◽  
S Szymik-Kantorowicz ◽  
P Daszkiewicz ◽  
...  
Keyword(s):  
Clinical Importance ◽  
Wilms Tumour ◽  
Heterozygosity Loss

scholarly journals Effects of Different Simulated Management Intensities on The Genetic Diversity of a Heart-of-palm Tree Natural Population (Euterpe edulis Martius)

2010 ◽  
Vol 59 (1-6) ◽  
pp. 201-210 ◽  
Author(s):  
Juliano Zago Da Silva ◽  
Maurício Sedrez Dos Reis
Keyword(s):  
Genetic Diversity ◽  
Genetic Characterization ◽  
Selective Logging ◽  
Fixation Index ◽  
Palm Tree ◽  
Euterpe Edulis ◽  
Heterozygosity Loss ◽  
Euterpe Edulis Martius ◽  
Total Seed ◽  
The Impact

Abstract The objective of this study was to evaluate the impact of selective logging on genetic diversity and inbreeding a heart-of-palm tree (Euterpe edulis), simulating different cutting intensities. To detect the effects of logging, we first performed the genetic characterization of the reproductive plants present in 24 plots that were allocated in Ibirama-SC, Brazil. For the genetic characterization we used allozyme markers, and for simulating the occurrence of different cutting intensities (5, 10, 20, 30, 40, 50, 60 and 150 seed-trees/ha) we performed 1000 resamplings within the total seed-tree group (599). Thus, it was possible to compare the genetic diversity among the different cutting intensities and the unmanaged population, through alterations to the allelic frequencies, heterozygosity, loss of alleles and increase in the inbreeding. The results of genetic indexes for different cutting intensity were variable, but all presented the same tendency towards genetic diversity reduction when the density of the seed-trees/ha was reduced. The results show that the density of 60 seed-trees/ha, or higher are the most indicated when the objective is to utilize this natural resource in a sustainable way as regards the management issues, because they did not present loss of alleles or reduction in the number of polymorphic loci, and also because they presented the lowest reductions in the observed and expected heterozygosity index and fixation index.

scholarly journals Detection of Cryptic Sex in Automictic Populations: Theoretical Expectations and a Case Study in Cataglyphis Desert Ants

2021 ◽  
Vol 9 ◽  
Author(s):  
Alexandre Kuhn ◽  
Serge Aron ◽  
Olivier J. Hardy
Keyword(s):  
Asexual Reproduction ◽  
Reproductive Strategies ◽  
Relative Rate ◽  
Natural Populations ◽  
Colony Development ◽  
Genetic Structure Of Populations ◽  
Heterozygosity Loss ◽  
Sexual Production ◽  
Cryptic Sex ◽  
The Individual

Reproductive strategies are diverse and a whole continuum of mixed systems lies between strict sexuality and strict clonality (apomixis), including automixis, a parthenogenetic mode of reproduction involving a meiosis and increasing homozygosity over generations. These various systems impact the genetic structure of populations, which can therefore be used to infer reproductive strategies in natural populations. Here, we first develop a mathematical model, validated by simulations, to predict heterozygosity and inbreeding in mixed sexual-automictic populations. It highlights the predominant role of the rate of heterozygosity loss experienced during automixis (γ), which is locus dependent. When γ is low, mixed populations behave like purely sexual ones until sex becomes rare. In contrast, when γ is high, the erosion of genetic diversity is tightly correlated to the rate of sex, so that the individual inbreeding coefficient can inform on the ratio of sexual/asexual reproduction. In the second part of this study, we used our model to test the presence of cryptic sex in a hybridogenetic Cataglyphis ant where new queens are produced parthenogenetically, leaving males with an apparent null fitness while they are essential to colony development as sperm is required to produce workers. Occasional sexual production of queens could resolve this paradox by providing males some fertile progeny. To determine whether this occurs in natural populations, we simulated genotypic datasets in a population under various regimes of sexual vs. asexual reproduction for queen production and compared the distribution of inbreeding, expected heterozygosity and inter-individual relatedness coefficients with those observed in a natural population of Cataglyphis mauritanica using microsatellites. Our simulations show that the distribution of inter-individual relatedness coefficients was particularly informative to assess the relative rate of sexual/asexual reproduction, and our dataset was compatible with pure parthenogenesis but also with up to 2% sexual reproduction. Our approach, implemented in an R script, should be useful to assess reproductive strategies in other biological models.

Heterozygosity, Loss of

2005 ◽  
Author(s):  
Hawkins B. De France ◽  
Elaine A. Ostrander
Keyword(s):  
Heterozygosity Loss
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