scholarly journals Uniparental Disomy and Genomic Imprinting in Humans

1996 ◽  
Vol 45 (1-2) ◽  
pp. 145-152
Author(s):  
A. Schinzel
Keyword(s):  
Genomic Imprinting ◽  
Uniparental Disomy ◽  
Paternal Allele ◽  
Chromosome 22 ◽  
Loss Of Function ◽  
Developmental Defects ◽  
Robertsonian Translocations ◽  
Healthy Mother ◽  
Active Allele ◽  
Or Genes

Uniparental disomy (UPD), the inheritance of both homologues from one chromosome from the same parent, was first proposed in 1980 by Erik Engel [1] to be a potential cause of congenital developmental defects in hymans. First hints from the premolecular era towards its existence came from instances where a pericentric inversion was present on one homologue in a parent and on both in one offspring [2] and where there was transmission of an interhomologous Robertsonian translocation (of chromosome 22) from a healthy mother to healthy offspring [3-4]. In mice, UPD was experimentally produced by crossing two mice lines with different Robertsonian translocations both involving the same chromosome [for 2 review see ref. 5].Through this approach, it was possible to define imprinted regions, chromosomes and chromosomal segments for which either maternal or paternal or both types of uniparental disomy led to phenotypic abnormalities. The latter are explained by genomic imprinting, the differential silencing of a gene or genes from one of the parents (the mother or the father) during any stage of embryogenesis or later in life. If, for example, the maternal homologue of a given gene is imprinted (and hence only the paternal allele is active), maternal UPD would lead to loss of the active allele and thus might cause consequences due to loss of function.

scholarly journals Prader-Willi syndrome: reflections on seminal studies and future therapies

Open Biology ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 200195
Author(s):  
Michael S. Chung ◽  
Maéva Langouët ◽  
Stormy J. Chamberlain ◽  
Gordon G. Carmichael
Keyword(s):  
Genomic Imprinting ◽  
Angelman Syndrome ◽  
Cpg Island ◽  
Uniparental Disomy ◽  
Large Deletion ◽  
Paternal Allele ◽  
Prader Willi Syndrome ◽  
Loss Of Function ◽  
Maternal Uniparental Disomy ◽  
Parental Allele

Prader-Willi syndrome (PWS) is caused by the loss of function of the paternally inherited 15q11-q13 locus. This region is governed by genomic imprinting, a phenomenon in which genes are expressed exclusively from one parental allele. The genomic imprinting of the 15q11-q13 locus is established in the germline and is largely controlled by a bipartite imprinting centre. One part, termed the Prader-Willi syndrome imprinting center (PWS-IC), comprises a CpG island that is unmethylated on the paternal allele and methylated on the maternal allele. The second part, termed the Angelman syndrome imprinting centre, is required to silence the PWS_IC in the maternal germline. The loss of the paternal contribution of the imprinted 15q11-q13 locus most frequently occurs owing to a large deletion of the entire imprinted region but can also occur through maternal uniparental disomy or an imprinting defect. While PWS is considered a contiguous gene syndrome based on large-deletion and uniparental disomy patients, the lack of expression of only non-coding RNA transcripts from the SNURF-SNRPN/SNHG14 may be the primary cause of PWS. Patients with small atypical deletions of the paternal SNORD116 cluster alone appear to have most of the PWS related clinical phenotypes. The loss of the maternal contribution of the 15q11-q13 locus causes a separate and distinct condition called Angelman syndrome. Importantly, while much has been learned about the regulation and expression of genes and transcripts deriving from the 15q11-q13 locus, there remains much to be learned about how these genes and transcripts contribute at the molecular level to the clinical traits and developmental aspects of PWS that have been observed.

scholarly journals Multiple Imprinted Genes Associated with Prader-Willi Syndrome and Location of an Imprinting Control Element

1996 ◽  
Vol 45 (1-2) ◽  
pp. 87-89
Author(s):  
R.D. Nicholls ◽  
M.T.C. Jong ◽  
C.C. Glenn ◽  
J. Gabriel ◽  
P.K. Rogan ◽  
...  
Keyword(s):  
Genomic Imprinting ◽  
Epigenetic Modification ◽  
Uniparental Disomy ◽  
Paternal Allele ◽  
Control Element ◽  
Parental Origin ◽  
Imprinted Genes ◽  
Mammalian Development ◽  
Specific Expression ◽  
Large Deletions

Our studies aim to identify the mechanisms and genes involved in genomic imprinting in mammalian development and human disease. Imprinting refers to an epigenetic modification of DNA that results in parent-of-origin specific expression during embryogenesis and in the adult. This imprint is reset at each generation, depending on the sex of the parental gametogenesis. Prader-Willi (PWS) and Angelman (AS) syndromes are excellent models for the study of genomic imprinting in humans, since these distinct neurobehavioural disorders are both associated with genetic abnormalities (large deletions, uniparental disomy, and imprinting mutations) of inheritance in chromosome 15q11-q13, dependent on the parental origin (reviewed in ref. 1). Some AS patients have biparental inheritance, consistent with a single imprinted gene (active on the maternal chromosome), whereas similar PWS patients are not found suggesting that at least two imprinted genes (active on the paternal allele) may be necessary for classical PWS. We have previously shown that the small ribonucleoprotein associated protein SmN gene (SNRPN), located in the PWS critical region [2], is only expressed from the paternal allele and is differentially methylated on parental alleles [3]. Therefore, SNRPN may have a role in PWS. Methylation imprints have also been found at two other loci in 15q11-q13, PW71 [4] and D15S9 [5], which map 120 kb and 1.5 Mb proximal to SNRPN, respectively. We have now characterized in detail the gene structure and expression from two imprinted loci within 15q11-q13, SNRPN and D15S9, which suggests that both loci are surprisingly complex, with important implications for the pathogenesis of PWS.

scholarly journals Basics and disturbances of genomic imprinting

2020 ◽  
Vol 32 (4) ◽  
pp. 297-304
Author(s):  
Dirk Prawitt ◽  
Thomas Haaf
Keyword(s):  
Genomic Imprinting ◽  
Primordial Germ Cells ◽  
Uniparental Disomy ◽  
Point Mutations ◽  
Paternal Allele ◽  
Imprinted Genes ◽  
Specific Expression ◽  
Imprinting Disorders ◽  
Increased Risk ◽  
Genomic Imprints

Abstract Genomic imprinting ensures the parent-specific expression of either the maternal or the paternal allele, by different epigenetic processes (DNA methylation and histone modifications) that confer parent-specific marks (imprints) in the paternal and maternal germline, respectively. Most protein-coding imprinted genes are involved in embryonic growth, development, and behavior. They are usually organized in genomic domains that are regulated by differentially methylated regions (DMRs). Genomic imprints are erased in the primordial germ cells and then reset in a gene-specific manner according to the sex of the germline. The imprinted genes regulate and interact with other genes, consistent with the existence of an imprinted gene network. Defects of genomic imprinting result in syndromal imprinting disorders. To date a dozen congenital imprinting disorders are known. Usually, a given imprinting disorder can be caused by different types of defects, including point mutations, deletions/duplications, uniparental disomy, and epimutations. Causative trans-acting factors in imprinting disorders, including ZFP57 and the subcortical maternal complex (SCMC), have the potential to affect multiple DMRs across the genome, resulting in a multi-locus imprinting disturbance. There is evidence that mutations in components of the SCMC can confer an increased risk for imprinting disorders.

Genetic imprinting in clinical genetics

Development ◽  
1990 ◽  
Vol 108 (Supplement) ◽  
pp. 131-139
Author(s):  
Angus Clarke
Keyword(s):  
Genomic Imprinting ◽  
Fragile Site ◽  
Fragile X ◽  
Single Gene ◽  
Hydatidiform Mole ◽  
Uniparental Disomy ◽  
Clinical Genetics ◽  
Growth Disorders ◽  
Developmental Defects ◽  
Genetic Imprinting

Genetic, and indeed genomic, imprinting does occur in humans. This is manifest at the level of the genome, the individual chromosome, subchromosomal region or fragile site, or the single locus. The best evidence at the single gene level comes from a consideration of familial tumour syndromes. Chromosomal imprinting effects are revealed when uniparental disomy occurs, as in the Prader-Willi syndrome and doubtless other sporadic, congenital anomaly syndromes. Genomic imprinting is manifest in the developmental defects of hydatidiform mole, teratoma and triploidy. Fragile (X) mental retardation shows an unusual pattern of inheritance, and imprinting can account for these effects. Future work in clinical genetics may identify congenital anomalies and growth disorders caused by imprinting: the identification of imprinting effects for specific chromosomal regions in mice will allow the examination of the homologous chromosomal region in humans.

scholarly journals mRNA Surveillance Complex PELOTA-HBS1 Regulates Phosphoinositide-Dependent Protein Kinase1 and Plant Growth

2021 ◽  
Author(s):  
Wei Kong ◽  
Shutang Tan ◽  
Qing Zhao ◽  
De-Li Lin ◽  
Zhi-Hong Xu ◽  
...  
Keyword(s):  
Quality Control ◽  
Messenger Rna ◽  
Loss Of Function ◽  
Yeast Saccharomyces Cerevisiae ◽  
Developmental Defects ◽  
Mrna Surveillance ◽  
Dna Insertion ◽  
Dependent Protein ◽  
Heterodimeric Complex ◽  
Severe Growth

Abstract The quality control system for messenger RNA (mRNA) is fundamental for cellular activities in eukaryotes. To elucidate the molecular mechanism of 3’-Phosphoinositide-Dependent Protein Kinase1 (PDK1), a master regulator that is essential throughout eukaryotic growth and development, we employed a forward genetic approach to screen for suppressors of the loss-of-function T-DNA insertion double mutant pdk1.1 pdk1.2 in Arabidopsis thaliana. Notably, the severe growth attenuation of pdk1.1 pdk1.2 was rescued by sop21 (suppressor of pdk1.1 pdk1.2), which harbours a loss-of-function mutation in PELOTA1 (PEL1). PEL1 is a homologue of mammalian PELOTA and yeast (Saccharomyces cerevisiae) DOM34p, which each form a heterodimeric complex with the GTPase HBS1 (HSP70 SUBFAMILY B SUPPRESSOR1, also called SUPERKILLER PROTEIN7, SKI7), a protein that is responsible for ribosomal rescue and thereby assures the quality and fidelity of mRNA molecules during translation. Genetic analysis further revealed that a dysfunctional PEL1-HBS1 complex failed to degrade the T-DNA-disrupted PDK1 transcripts, which were truncated but functional, and thus rescued the growth and developmental defects of pdk1.1 pdk1.2. Our studies demonstrated the functionality of a homologous PELOTA-HBS1 complex and identified its essential regulatory role in plants, providing insights into the mechanism of mRNA quality control.

scholarly journals Inner Ear and Muscle Developmental Defects in Smpx-Deficient Zebrafish Embryos

2021 ◽  
Vol 22 (12) ◽  
pp. 6497
Author(s):  
Anna Ghilardi ◽  
Alberto Diana ◽  
Renato Bacchetta ◽  
Nadia Santo ◽  
Miriam Ascagni ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Inner Ear ◽  
Hair Cells ◽  
Muscle Fibers ◽  
Underlying Mechanism ◽  
Loss Of Function ◽  
Zebrafish Model ◽  
Developmental Defects ◽  
Inner Ear Development ◽  
Syndromic Hearing Loss

The last decade has witnessed the identification of several families affected by hereditary non-syndromic hearing loss (NSHL) caused by mutations in the SMPX gene and the loss of function has been suggested as the underlying mechanism. In the attempt to confirm this hypothesis we generated an Smpx-deficient zebrafish model, pointing out its crucial role in proper inner ear development. Indeed, a marked decrease in the number of kinocilia together with structural alterations of the stereocilia and the kinocilium itself in the hair cells of the inner ear were observed. We also report the impairment of the mechanotransduction by the hair cells, making SMPX a potential key player in the construction of the machinery necessary for sound detection. This wealth of evidence provides the first possible explanation for hearing loss in SMPX-mutated patients. Additionally, we observed a clear muscular phenotype consisting of the defective organization and functioning of muscle fibers, strongly suggesting a potential role for the protein in the development of muscle fibers. This piece of evidence highlights the need for more in-depth analyses in search for possible correlations between SMPX mutations and muscular disorders in humans, thus potentially turning this non-syndromic hearing loss-associated gene into the genetic cause of dysfunctions characterized by more than one symptom, making SMPX a novel syndromic gene.

scholarly journals Mosaic Segmental and Whole-Chromosome upd(11)mat in Silver-Russell Syndrome

Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 581
Author(s):  
Laura Pignata ◽  
Angela Sparago ◽  
Orazio Palumbo ◽  
Elena Andreucci ◽  
Elisabetta Lapi ◽  
...  
Keyword(s):  
Molecular Level ◽  
Opposite Sign ◽  
Uniparental Disomy ◽  
Differentially Methylated Region ◽  
Imprinted Genes ◽  
Loss Of Function ◽  
Growth Disturbances ◽  
Molecular Defects ◽  
Entire Chromosome ◽  
Silver Russell Syndrome

Molecular defects altering the expression of the imprinted genes of the 11p15.5 cluster are responsible for the etiology of two congenital disorders characterized by opposite growth disturbances, Silver–Russell syndrome (SRS), associated with growth restriction, and Beckwith–Wiedemann syndrome (BWS), associated with overgrowth. At the molecular level, SRS and BWS are characterized by defects of opposite sign, including loss (LoM) or gain (GoM) of methylation at the H19/IGF2:intergenic differentially methylated region (H19/IGF2:IG-DMR), maternal or paternal duplication (dup) of 11p15.5, maternal (mat) or paternal (pat) uniparental disomy (upd), and gain or loss of function mutations of CDKN1C. However, while upd(11)pat is found in 20% of BWS cases and in the majority of them it is segmental, upd(11)mat is extremely rare, being reported in only two SRS cases to date, and in both of them is extended to the whole chromosome. Here, we report on two novel cases of mosaic upd(11)mat with SRS phenotype. The upd is mosaic and isodisomic in both cases but covers the entire chromosome in one case and is restricted to 11p14.1-pter in the other case. The segmental upd(11)mat adds further to the list of molecular defects of opposite sign in SRS and BWS, making these two imprinting disorders even more specular than previously described.

scholarly journals Identification and validation of novel candidate risk genes in endocytic vesicular trafficking associated with esophageal atresia and tracheoesophageal fistulas

2021 ◽  
Author(s):  
Guojie Zhong ◽  
Priyanka Ahimaz ◽  
Nicole A. Edwards ◽  
Jacob J. Hagen ◽  
Christophe Faure ◽  
...  
Keyword(s):  
Genetic Variants ◽  
Congenital Anomalies ◽  
De Novo ◽  
Simulation Analysis ◽  
Loss Of Function ◽  
Developmental Defects ◽  
Risk Genes ◽  
Significant Burden ◽  
Background Mutation Rate ◽  
Complex Cases

Esophageal atresias/tracheoesophageal fistulas (EA/TEF) are rare congenital anomalies caused by aberrant development of the foregut. Previous studies indicate that rare or de novo genetic variants significantly contribute to EA/TEF risk, and most individuals with EA/TEF do not have pathogenic genetic variants in established risk genes. To identify novel genetic contributions to EA/TEF, we performed whole genome sequencing of 185 trios (probands and parents) with EA/TEF, including 59 isolated and 126 complex cases with additional congenital anomalies and/or neurodevelopmental disorders. There was a significant burden of protein altering de novo coding variants in complex cases (p=3.3e-4), especially in genes that are intolerant of loss of function variants in the population. We performed simulation analysis of pathway enrichment based on background mutation rate and identified a number of pathways related to endocytosis and intracellular trafficking that as a group have a significant burden of protein altering de novo variants. We assessed 18 variants for disease causality using CRISPR-Cas9 mutagenesis in Xenopus and confirmed 13 with tracheoesophageal phenotypes. Our results implicate disruption of endosome-mediated epithelial remodeling as a potential mechanism of foregut developmental defects. This research may have implications for the mechanisms of other rare congenital anomalies.

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