High-resolution custom array spanning Xq22 region to study patients carrying PLP1 copy number gain
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE138542 | GEO | 2019/10/09
REPOSITORIES: GEO
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Project description:Inverted repeats (IRs) can facilitate structural variation as crucibles of genomic rearrangement. Complex DUP-TRP/INV-DUP rearrangements that contain breakpoint junctions within IRs have been recently associated with both MECP2 duplication syndrome (MIM#300260) and Pelizaeus-Merzbacher disease (PMD, MIM#312080). We investigated 17 unrelated PMD subjects with copy number gains at the PLP1 locus including triplication and quadruplication of specific genomic intervals M-bM-^@M-^S 16/17 were found to have a DUP-TRP/INV-DUP rearrangement product. An IR distal to PLP1 facilitates DUP-TRP/INV-DUP formation as well as an inversion structural variation found frequently amongst normal individuals. We show that a homologyM-bM-^@M-^Tor homeologyM-bM-^@M-^Tdriven replicative mechanism of DNA repair can apparently mediate template switches within stretches of microhomology. Moreover, we provide evidence that quadruplication, and potentially higher order amplification of a genomic interval, can occur in a manner consistent with rolling circle amplification as predicted by the microhomology mediated break induced replication (MMBIR) model. To determine size, genomic extent and gene content for each rearrangement, we used a customized tiling-path oligonucleotide microarray spanning the Xq22 chromosomal region to query the genomic DNA of 7 males with Pelizaeus-Merzbacher disease, and 5 unaffected or carrier/unaffected family members. A 4x44k Agilent Technologies (Santa Clara, CA) microarray was designed using the Agilent e-array website targeting the region of the genome encompassing the dosage-sensitive PLP1 gene.
2014-11-25 | E-GEOD-63594 | biostudies-arrayexpress
Project description:Inverted repeats (IRs) can facilitate structural variation as crucibles of genomic rearrangement. Complex DUP-TRP/INV-DUP rearrangements that contain breakpoint junctions within IRs have been recently associated with both MECP2 duplication syndrome (MIM#300260) and Pelizaeus-Merzbacher disease (PMD, MIM#312080). We investigated 17 unrelated PMD subjects with copy number gains at the PLP1 locus including triplication and quadruplication of specific genomic intervals – 16/17 were found to have a DUP-TRP/INV-DUP rearrangement product. An IR distal to PLP1 facilitates DUP-TRP/INV-DUP formation as well as an inversion structural variation found frequently amongst normal individuals. We show that a homology—or homeology—driven replicative mechanism of DNA repair can apparently mediate template switches within stretches of microhomology. Moreover, we provide evidence that quadruplication, and potentially higher order amplification of a genomic interval, can occur in a manner consistent with rolling circle amplification as predicted by the microhomology mediated break induced replication (MMBIR) model.
2014-11-25 | GSE63594 | GEO
Project description:Pelizaeus-Merzbacher disease (PMD) is a pediatric disease of myelin in the central nervous system and manifests with a wide spectrum of clinical severities. Although PMD is a rare monogenic disease, hundreds of mutations in the X-linked myelin gene proteolipid protein 1 (PLP1) have been identified in humans. Attempts to identify a common pathogenic process underlying PMD have been complicated by an incomplete understanding of PLP1 dysfunction and limited access to primary human oligodendrocytes. To address this, we generated panels of human induced pluripotent stem cells (hiPSCs) and hiPSC-derived oligodendrocytes from 12 individuals with mutations spanning the genetic and clinical diversity of PMD—including point mutations and duplication, triplication, and deletion of PLP1—and developed an in vitro platform for molecular and cellular characterization of all 12 mutations simultaneously. We identified individual and shared defects in PLP1 mRNA expression and splicing, oligodendrocyte progenitor development, and oligodendrocyte morphology and capacity for myelination. These observations enabled classification of PMD subgroups by cell-intrinsic phenotypes and identified a subset of mutations for targeted testing of small-molecule modulators of the endoplasmic reticulum stress response, which improved both morphologic and myelination defects. Collectively, these data provide insights into the pathogeneses of a variety of PLP1 mutations and suggest that disparate etiologies of PMD could require specific treatment approaches for subsets of individuals. More broadly, this study demonstrates the versatility of a hiPSC-based panel spanning the mutational heterogeneity within a single disease and establishes a widely applicable platform for genotype-phenotype correlation and drug screening in any human myelin disorder.
2017-04-04 | GSE96049 | GEO
Project description:Pelizaeus-Merzbacher disease (PMD) is a severe hypomyelinating disease, characterized by ataxia, intellectual disability, epilepsy and premature death. In the majority of cases, PMD is caused by duplication of PLP1 that is expressed in myelinating oligodendrocytes. Despite detailed knowledge of PLP1, there is presently no curative therapy for PMD. We used a Plp1 transgenic PMD mouse model to test the therapeutic effect of Lonaprisan, an antagonist of the nuclear progesterone receptor, in lowering Plp1 mRNA overexpression. We applied placebo-controlled Lonaprisan therapy to PMD mice for 10 weeks and performed the grid slip analysis to assess the clinical phenotype. Additionally, mRNA expression and protein accumulation as well as histological analysis of the central nervous system were performed. While Plp1 mRNA levels are increased about 1.8-fold in PMD mice compared to wildtype controls, daily Lonaprisan treatment reduced overexpression at the RNA level up to 1.5-fold, which was sufficient to significantly improve a poor motor phenotype. Electron microscopy confirmed a 25% increase in the number of myelinated axons in the corticospinal tract when compared to untreated PMD mice. Microarray analysis revealed the upregulation of pro-apoptotic genes in PMD mice that could be partially rescued by Lonaprisan treatment, which also reduced microgliosis, astrogliosis, and lymphocyte infiltration. We treated mice with Lonaprisan or vehicle for 10 weeks. Brains from 13 week old mice were collected and subsequently lysed for total RNA extraction. We took three biological replicates for each Treatment and Placebo.
2014-02-26 | E-GEOD-55315 | biostudies-arrayexpress
Project description:Pelizaeus-Merzbacher disease (PMD) is a severe hypomyelinating disease, characterized by ataxia, intellectual disability, epilepsy and premature death. In the majority of cases, PMD is caused by duplication of PLP1 that is expressed in myelinating oligodendrocytes. Despite detailed knowledge of PLP1, there is presently no curative therapy for PMD. We used a Plp1 transgenic PMD mouse model to test the therapeutic effect of Lonaprisan, an antagonist of the nuclear progesterone receptor, in lowering Plp1 mRNA overexpression. We applied placebo-controlled Lonaprisan therapy to PMD mice for 10 weeks and performed the grid slip analysis to assess the clinical phenotype. Additionally, mRNA expression and protein accumulation as well as histological analysis of the central nervous system were performed. While Plp1 mRNA levels are increased about 1.8-fold in PMD mice compared to wildtype controls, daily Lonaprisan treatment reduced overexpression at the RNA level up to 1.5-fold, which was sufficient to significantly improve a poor motor phenotype. Electron microscopy confirmed a 25% increase in the number of myelinated axons in the corticospinal tract when compared to untreated PMD mice. Microarray analysis revealed the upregulation of pro-apoptotic genes in PMD mice that could be partially rescued by Lonaprisan treatment, which also reduced microgliosis, astrogliosis, and lymphocyte infiltration.
2014-02-26 | GSE55315 | GEO
Project description:Unbalanced translocations are a relatively common type of copy number variation and are a major contributor to neurodevelopmental disorders. We analyzed the breakpoints of 57 unique unbalanced translocations to investigate the mechanisms of how they form. 51 are simple unbalanced translocations between two different chromosome ends, and six rearrangements have more than three breakpoints involving two to five chromosomes. Sequencing 37 breakpoint junctions revealed that simple translocations have between zero and four basepairs (bp) of microhomology (n=26), short inserted sequences (n=8), or paralogous repeats (n=3) at the junctions, indicating that translocations do not arise primarily from non-allelic homologous recombination, but instead form most often via non-homologous end joining or microhomology-mediated break-induced replication. Three simple translocations fuse genes that are predicted to produce in-frame transcripts of SIRPG-WWOX, SMOC2-PROX1, and PIEZO2-MTA1, which may lead to gain of function. Three complex translocations have inversions, insertions, and multiple breakpoint junctions between only two chromosomes. Whole- genome sequencing and fluorescence in situ hybridization analysis of two de novo translocations revealed at least 18 and 33 breakpoints involving five different chromosomes. Breakpoint sequencing of one inherited translocation involving four chromosomes uncovered multiple breakpoints with inversions and insertions. All of these breakpoint junctions had zero to four bp of microhomology consistent with germline chromothripsis, and both de novo events occurred on paternal alleles. Breakpoint sequencing of our large collection of chromosome rearrangements offers a comprehensive analysis of the molecular mechanisms behind germline translocation formation. High resolution array CGH; two-color experiment, clinical patient vs. normal control gDNA; sex mis-matched
2015-04-22 | E-GEOD-68019 | biostudies-arrayexpress
Project description:Genomic disorders are characterized by the presence of flanking segmental duplications that predispose these regions to recurrent rearrangement. Based on the duplication architecture of the genome we investigated 130 regions which we hypothesized as candidates for novel genomic disorders 1. We tested 290 patients with mental retardation by BAC array CGH, identifying sixteen pathogenic rearrangements, including four patients with de novo microdeletions of 17q21.31. Using oligonucleotide arrays we refined the breakpoints of this microdeletion, defining a 478 kb critical region containing six genes that were deleted in all four cases. The breakpoints of this deletion, and of four other pathogenic rearrangements in 1q21.1, 15q13, 15q24 and 17q12 were mapped to flanking segmental duplications, suggesting that these are also sites of recurrent rearrangement. In common with the 17q21.31 deletion, these breakpoint regions are also sites of copy number polymorphism in controls, indicating that these may be inherently unstable genomic regions. Keywords: BAC comparative genomic hybridization of individuals with mental retardation and congenital anomalies
2006-08-10 | GSE5373 | GEO
Project description:Unbalanced translocations are a relatively common type of copy number variation and are a major contributor to neurodevelopmental disorders. We analyzed the breakpoints of 57 unique unbalanced translocations to investigate the mechanisms of how they form. 51 are simple unbalanced translocations between two different chromosome ends, and six rearrangements have more than three breakpoints involving two to five chromosomes. Sequencing 37 breakpoint junctions revealed that simple translocations have between zero and four basepairs (bp) of microhomology (n=26), short inserted sequences (n=8), or paralogous repeats (n=3) at the junctions, indicating that translocations do not arise primarily from non-allelic homologous recombination, but instead form most often via non-homologous end joining or microhomology-mediated break-induced replication. Three simple translocations fuse genes that are predicted to produce in-frame transcripts of SIRPG-WWOX, SMOC2-PROX1, and PIEZO2-MTA1, which may lead to gain of function. Three complex translocations have inversions, insertions, and multiple breakpoint junctions between only two chromosomes. Whole- genome sequencing and fluorescence in situ hybridization analysis of two de novo translocations revealed at least 18 and 33 breakpoints involving five different chromosomes. Breakpoint sequencing of one inherited translocation involving four chromosomes uncovered multiple breakpoints with inversions and insertions. All of these breakpoint junctions had zero to four bp of microhomology consistent with germline chromothripsis, and both de novo events occurred on paternal alleles. Breakpoint sequencing of our large collection of chromosome rearrangements offers a comprehensive analysis of the molecular mechanisms behind germline translocation formation.
2015-04-22 | GSE68019 | GEO
Project description:We performed single-molecule telomere length and telomere fusion analysis in patients at different stages of chronic lymphocytic leukaemia (CLL). Our work identified the shortest telomeres ever recorded in primary human tissue reinforcing the concept that there is significant cell division in CLL. Furthermore, we provide direct evidence that critical telomere shortening, dysfunction and fusion contribute to disease progression. The frequency of short telomeres and fusion events increased with advanced disease, but importantly these were also found in a subset of early-stage patient samples indicating that these events can precede disease progression. Sequence analysis of fusion events isolated from individuals with the shortest telomeres revealed limited numbers of repeats at the breakpoint, sub-telomeric deletion and microhomology. Array-CGH analysis of individuals displaying evidence of telomere dysfunction revealed large-scale genomic rearrangements that were concentrated in the telomeric regions; this was not observed in samples with longer telomeres.
2010-05-28 | GSE22016 | GEO
Project description:Human genome structural variants (SVs) are caused by diverse mutational mechanisms. We used orthogonal long- and short-read sequencing technologies to investigate end products of de novo chromosome 17p11.2 rearrangements and query the molecular mechanisms underlying both recurrent and non-recurrent events. For non-recurrent events we found microhomology and microhomeology at the breakpoint junctions, an excess of deletion rearrangements on paternally-derived haplotypes, and elucidated recalcitrant breakpoints. Our data indicate an increased rate of clustered single nucleotide variant mutation in cis that is not present with recurrent rearrangement of the genome at the same locus. Indel and single nucleotide mutations are associated with both copy number gains and losses of 17p11.2, occur up to ~1 Mb away from the breakpoint junctions, and favor C>G transversion substitutions; results suggesting that single stranded DNA is formed during the genesis of the SV and providing compelling support for a microhomology-mediated break-induced replication mechanism for SV formation.
2019-01-17 | GSE125207 | GEO