Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Complex Genomic Rearrangements at the PLP1 Locus Include Triplication and Quadruplication

ABSTRACT: 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.

ORGANISM(S): Homo sapiens

SUBMITTER: Christine Beck

PROVIDER: E-GEOD-63594 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

ACCESS DATA

Similar Datasets

Project description:Angelman syndrome (AS) and interstitial duplication 15q autism (int dup(15)) are reciprocal genomic disorders caused by maternal deletion or duplication of the 15q11.2-q13 region. While AS is caused by maternal loss of 15q and maternal duplications of 15q can cause autism implicating the maternally expressed UBE3A gene in these phenotypes. We investigated chromatin and gene expression changes in blood and cell lines from three int dup(15) and three reciprocal AS deletion subjects to identify global genomic and gene expression changes that may influence both the AS and autism phenotypes. Using formaldehyde-assisted isolation of regulatory elements (FAIRE) we identified 1104 regions of differential open chromatin in AS deletion and 2344 regions int dup(15) indicating changes in chromatin could influence gene expression in these regions. Microarray analysis revealed 1225 genes that were elevated in AS deletion vs int dup(15) and 976 genes that were elevated in int dup(15) vs AS deletion PBMC (pvalue<0.05). Significant differences in expression were found for genes at the 15q locus like UBE3A, ATP10A and HERC2. A larger set of genes involved in chromatin remodeling, DNA repair and neurogenesis were found, at FAIRE peaks in AS deletion samples but had increased transcription in int dup(15) samples. There was a significant enhancement for genes with FOXP1 binding sites in the int dup(15) gene set and elevated FOXP1 protein could be detected in the nucleus of int dup(15) as compared to AS deletion cell lines. This analysis provides the first insights into transcriptional changes which may unveil new sets of genes and pathways contributing to both AS and autism pathogenesis. Gene expression was performed using 100ng of total RNA from each subject as starting material for amplification and cRNA synthesis in accordance Affymetrix protocols (http://tinyurl.com/3j7dcp6). Hybridizations were performed to the Affy HumanGene_st_v1 chip and the signal data normalized using internal chip controls. Normalized expression data was then exported to a text file for subsequent expression analysis using the EXPANDER software analysis suite.

Project description:MECP2 Duplication Syndrome, also known as X-linked intellectual developmental disorder Lubs type (MRXSL; MIM: 300260), is a neurodevelopmental disorder caused by copy number gains spanning MECP2. Despite varying genomic rearrangement structures, including duplications and triplications, and a wide range of duplication sizes, no clear correlation exists between DNA rearrangement and clinical features. We had previously demonstrated that up to 38% of MRXLS families are characterized by complex genomic rearrangements (CGRs) of intermediate complexity (2 ≤ CNV breakpoints < 5), yet the impact of these genomic structures on regulation of gene expression and phenotypic manifestations have not been investigated. To study the role of the genomic rearrangement structures on an individual’s clinical phenotypic variability, we employed a comprehensive genomics, transcriptomics, and deep phenotyping analysis approach on 137 individuals affected by MRXSL. Genomic structural information was correlated with transcriptomic and quantitative phenotypic analysis using Human Phenotype Ontology (HPO) semantic similarity scores. Duplication sizes in the cohort ranging from 64 kb to 16.5 Mb were classified into four categories comprising of tandem duplications (47%), terminal duplications (23%), inverted triplication structures (23%), and other CGRs (7%). A majority of the terminal duplication structures consist of translocations (65%) followed by recombinant chromosomes (23%). Notably, 67% of de novo events occurred in the terminal duplication group in contrast with 17% observed in tandem duplications. RNAseq data from lymphoblastoid cell lines indicated that the MECP2 transcript quantity in MECP2 triplications is statistically different from all duplications, but not between other classes of genomic structures. We also observed a significant (p < 0.05) correlation (Pearson R = 0.6, Spearman = 0.63) between the log-transformed MECP2 RNA levels and MeCP2 protein levels, demonstrating that genomic aberrations spanning MECP2 lead to altered MECP2 RNA and MeCP2 protein levels. Genotype-phenotype analyses indicated a gradual worsening of phenotypic features, including overall survival, developmental levels, microcephaly, epilepsy, and genitourinary/eye abnormalities in the following order: tandem duplications, other CGRs, terminal duplications/translocations, and triplications encompassing MECP2. In aggregate, this combined analysis uncovers an interplay between MECP2 dosage, genomic rearrangement structure and phenotypic traits. Whereas the level of MeCP2 is a key determinant of the phenotype, the DNA rearrangement structure can contribute to clinical severity and disease expression variability. Employing this type of analytical approach will advance our understanding of the impact of genomic rearrangements on genomic disorders and may help guide more targeted therapeutic approaches.

Dataset Information

Complex Genomic Rearrangements at the PLP1 Locus Include Triplication and Quadruplication

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets