UNIPARENTAL DISOMY: MECHANISMS AND CLINICAL CONSEQUENCES

2003 ◽  
Vol 14 (2) ◽  
pp. 155-175 ◽  
Author(s):  
LISA G SHAFFER
Keyword(s):  
Genomic Imprinting ◽  
Normal State ◽  
Diploid Number ◽  
Uniparental Disomy ◽  
Monoallelic Expression ◽  
Clinical Consequences ◽  
Epigenetic Phenomenon ◽  
Parent Of Origin

During gametogenesis in mammals, half of the parental chromosomes segregate to each gamete. Upon fertilization of two haploid gametes, the diploid number is restored (Figure 1A). Nondisjunction, malsegregation of the chromosomes during gametogenesis, can give rise to chromosomally unbalanced offspring (trisomies and monosomies) (Figure 1B). Genomic imprinting is an epigenetic phenomenon in which the activity of a gene is reversibly modified depending on the parent of origin. This leads to unequal, monoallelic expression of the maternal and paternal alleles of a diploid locus (Figure 1C). Thus, the normal state of an imprinted locus is an “imbalance”, not of chromosomes, but of the functional genetic content.

Imprinted small RNA genes

2004 ◽  
Vol 385 (10) ◽  
pp. 905-911 ◽  
Author(s):  
Hervé Seitz ◽  
Hélène Royo ◽  
Shau-Ping Lin ◽  
Neil Youngson ◽  
Anne C. Ferguson-Smith ◽  
...  
Keyword(s):  
Genomic Imprinting ◽  
Gene Families ◽  
Evolutionary Significance ◽  
Microrna Gene ◽  
Non Coding Rna ◽  
Epigenetic Phenomenon ◽  
Parent Of Origin ◽  
Microrna Genes ◽  
Rna Genes

Abstract Genomic imprinting is an epigenetic phenomenon that results in differential expression of both alleles, depending on their parent of origin. We have recently identified many imprinted small non-coding RNA genes belonging to the C/D RNA and microRNA gene families, both of which are usually known to play key roles in post-transcriptional metabolism of specific genes (e.g. C/D RNAs guide ribose methylation of target RNAs while microRNAs elicit either translational repression or RNA interference). Although the functional and evolutionary significance of this association between C/D RNA genes, microRNA genes and genomic imprinting is still highly elusive, these observations provide a framework for further analysis of the potential role of small non-coding RNAs in epigenetic control.

Loss of genomic imprinting in Drosophila clones

Genome ◽  
2006 ◽  
Vol 49 (8) ◽  
pp. 1043-1046 ◽  
Author(s):  
Andrew J Haigh ◽  
Vett K Lloyd
Keyword(s):  
Drosophila Melanogaster ◽  
Genomic Imprinting ◽  
X Chromosome ◽  
Chromatin Structure ◽  
Nuclear Transfer ◽  
Paternal Allele ◽  
Monoallelic Expression ◽  
C Elegans ◽  
Human Cancers ◽  
Parent Of Origin

Genomic imprinting is a process that genetically distinguishes maternal and paternal genomes, and can result in parent-of-origin-dependent monoallelic expression of a gene that is dependent on the parent of origin. As such, an otherwise functional maternally inherited allele may be silenced so that the gene is expressed exclusively from the paternal allele, or vice versa. Once thought to be restricted to mammals, genomic imprinting has been documented in angiosperm plants (J.L. Kermicle. 1970. Genetics, 66: 69–85), zebrafish (C.C. Martin and R. McGowan. 1995. Genet. Res. 65: 21–28), insects, and C. elegans (C.J. Bean, C.E. Schaner, and W.G. Kelly. 2004. Nat. Genet. 36: 100–105.). In each case, it appears to rely on differential chromatin structure. Aberrant imprinting has been implicated in various human cancers and has been detected in a number of cloned mammals, potentially limiting the usefulness of somatic nuclear transfer. Here we show that genomic imprinting associated with a mini-X chromosome is lost in Drosophila melanogaster clones.Key words: cloning, Drosophila, genomic imprinting, nuclear transfer.

scholarly journals Canonical and Non-canonical Genomic Imprinting in Rodents

2021 ◽  
Vol 9 ◽  
Author(s):  
Hisato Kobayashi
Keyword(s):  
Dna Methylation ◽  
Genomic Imprinting ◽  
Mouse Genome ◽  
Genetic Regulation ◽  
Imprinted Genes ◽  
Evolutionary Divergence ◽  
Chromatin Modifications ◽  
Allele Specific ◽  
Epigenetic Phenomenon ◽  
Parent Of Origin

Genomic imprinting is an epigenetic phenomenon that results in unequal expression of homologous maternal and paternal alleles. This process is initiated in the germline, and the parental epigenetic memories can be maintained following fertilization and induce further allele-specific transcription and chromatin modifications of single or multiple neighboring genes, known as imprinted genes. To date, more than 260 imprinted genes have been identified in the mouse genome, most of which are controlled by imprinted germline differentially methylated regions (gDMRs) that exhibit parent-of-origin specific DNA methylation, which is considered primary imprint. Recent studies provide evidence that a subset of gDMR-less, placenta-specific imprinted genes is controlled by maternal-derived histone modifications. To further understand DNA methylation-dependent (canonical) and -independent (non-canonical) imprints, this review summarizes the loci under the control of each type of imprinting in the mouse and compares them with the respective homologs in other rodents. Understanding epigenetic systems that differ among loci or species may provide new models for exploring genetic regulation and evolutionary divergence.

scholarly journals Evolution and function of genomic imprinting in plants

2015 ◽  
Vol 29 (24) ◽  
pp. 2517-2531 ◽  
Author(s):  
Jessica A. Rodrigues ◽  
Daniel Zilberman
Keyword(s):  
Genomic Imprinting ◽  
Histone Methylation ◽  
Biological Significance ◽  
Flowering Plants ◽  
Evolutionary Forces ◽  
Plant Genes ◽  
Epigenetic Phenomenon ◽  
Parent Of Origin ◽  
And Function ◽  
Genome Scale

Genomic imprinting, an inherently epigenetic phenomenon defined by parent of origin-dependent gene expression, is observed in mammals and flowering plants. Genome-scale surveys of imprinted expression and the underlying differential epigenetic marks have led to the discovery of hundreds of imprinted plant genes and confirmed DNA and histone methylation as key regulators of plant imprinting. However, the biological roles of the vast majority of imprinted plant genes are unknown, and the evolutionary forces shaping plant imprinting remain rather opaque. Here, we review the mechanisms of plant genomic imprinting and discuss theories of imprinting evolution and biological significance in light of recent findings.

scholarly journals An Introduction to Genomic Imprinting and Parent of Origin Effects

1996 ◽  
Vol 45 (1-2) ◽  
pp. 59-61
Author(s):  
J.G. Hall ◽  
E. Lopez-Rangel
Keyword(s):  
Genomic Imprinting ◽  
Protein Interactions ◽  
Uniparental Disomy ◽  
Protein Protein Interactions ◽  
Human Heredity ◽  
Expression Of Genes ◽  
Recent Developments ◽  
Genetic Mechanisms ◽  
Parent Of Origin ◽  
Origin Effects

Recent developments in molecular genetics and cytogenetics have allowed for better understanding of the inheritance and expression of genes. Many newly recognized mechanisms such as genomic imprinting, mosaicism, allelic expansion, cytoplasmic inheritance and uniparental disomy have been recognized to play an important role in human heredity.Genomic imprinting refers to differences in the phenotype which are observed depending on whether the gene was inherited from the father or from the mother. Genomic imprinting is a difficult concept to understand because imprinting has been used loosely to refer to a number of different mechanisms including psychological development, endocrinological actions of cells and protein-protein interactions. Genomic imprinting produces parent-of-origin effects. Parent-of-origin effects is a term that encompasses many of the non-traditional types of inheritance and other genetic and non-genetic mechanisms which show an effect depending on whether they were paternally or maternally derived.

scholarly journals Paternally expressed imprinted genes establish postzygotic hybridization barriers in Arabidopsis thaliana

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Philip Wolff ◽  
Hua Jiang ◽  
Guifeng Wang ◽  
Juan Santos-González ◽  
Claudia Köhler
Keyword(s):  
Arabidopsis Thaliana ◽  
Differential Expression ◽  
Seed Development ◽  
Genomic Imprinting ◽  
Imprinted Genes ◽  
Functional Requirement ◽  
Functional Roles ◽  
Epigenetic Phenomenon ◽  
Parent Of Origin

Genomic imprinting is an epigenetic phenomenon causing parent-of-origin specific differential expression of maternally and paternally inherited alleles. While many imprinted genes have been identified in plants, the functional roles of most of them are unknown. In this study, we systematically examine the functional requirement of paternally expressed imprinted genes (PEGs) during seed development in Arabidopsis thaliana. While none of the 15 analyzed peg mutants has qualitative or quantitative abnormalities of seed development, we identify three PEGs that establish postzygotic hybridization barriers in the endosperm, revealing that PEGs have a major role as speciation genes in plants. Our work reveals that a subset of PEGs maintains functional roles in the inbreeding plant Arabidopsis that become evident upon deregulated expression.

scholarly journals Quantitative and functional interrogation of parent-of-origin allelic expression biases in the brain

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Julio D Perez ◽  
Nimrod D Rubinstein ◽  
Daniel E Fernandez ◽  
Stephen W Santoro ◽  
Leigh A Needleman ◽  
...  
Keyword(s):  
Genomic Imprinting ◽  
Gene Dosage ◽  
Transcript Level ◽  
Monoallelic Expression ◽  
Strongly Correlated ◽  
Parent Of Origin ◽  
Parental Bias ◽  
The Brain ◽  
Specific Neuron ◽  
Specific Deletion

The maternal and paternal genomes play different roles in mammalian brains as a result of genomic imprinting, an epigenetic regulation leading to differential expression of the parental alleles of some genes. Here we investigate genomic imprinting in the cerebellum using a newly developed Bayesian statistical model that provides unprecedented transcript-level resolution. We uncover 160 imprinted transcripts, including 41 novel and independently validated imprinted genes. Strikingly, many genes exhibit parentally biased—rather than monoallelic—expression, with different magnitudes according to age, organ, and brain region. Developmental changes in parental bias and overall gene expression are strongly correlated, suggesting combined roles in regulating gene dosage. Finally, brain-specific deletion of the paternal, but not maternal, allele of the paternally-biased Bcl-x, (Bcl2l1) results in loss of specific neuron types, supporting the functional significance of parental biases. These findings reveal the remarkable complexity of genomic imprinting, with important implications for understanding the normal and diseased brain.

Review Article: Genomic imprinting: concept and clinical consequences

1999 ◽  
Vol 31 (1) ◽  
pp. 4-11 ◽  
Author(s):  
Marcel Mannens ◽  
Mariëlle Alders
Keyword(s):  
Genomic Imprinting ◽  
Review Article ◽  
Clinical Consequences

An N-Ethyl-N-Nitrosourea Mutagenesis Screen for Epigenetic Mutations in the Mouse

Genetics ◽  
2003 ◽  
Vol 164 (4) ◽  
pp. 1481-1494
Author(s):  
Ivona Percec ◽  
Joanne L Thorvaldsen ◽  
Robert M Plenge ◽  
Christopher J Krapp ◽  
Joseph H Nadeau ◽  
...  
Keyword(s):  
Genomic Imprinting ◽  
X Chromosome ◽  
X Inactivation ◽  
Monoallelic Expression ◽  
Chromosome 15 ◽  
Chromosome 5 ◽  
Chromosome 10 ◽  
Mutagenesis Screen ◽  
Distal Chromosome ◽  
Males And Females

Abstract The mammalian epigenetic phenomena of X inactivation and genomic imprinting are incompletely understood. X inactivation equalizes X-linked expression between males and females by silencing genes on one X chromosome during female embryogenesis. Genomic imprinting functionally distinguishes the parental genomes, resulting in parent-specific monoallelic expression of particular genes. N-ethyl-N-nitrosourea (ENU) mutagenesis was used in the mouse to screen for mutations in novel factors involved in X inactivation. Previously, we reported mutant pedigrees identified through this screen that segregate aberrant X-inactivation phenotypes and we mapped the mutation in one pedigree to chromosome 15. We now have mapped two additional mutations to the distal chromosome 5 and the proximal chromosome 10 in a second pedigree and show that each of the mutations is sufficient to induce the mutant phenotype. We further show that the roles of these factors are specific to embryonic X inactivation as neither genomic imprinting of multiple genes nor imprinted X inactivation is perturbed. Finally, we used mice bearing selected X-linked alleles that regulate X chromosome choice to demonstrate that the phenotypes of all three mutations are consistent with models in which the mutations have affected molecules involved specifically in the choice or the initiation of X inactivation.

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