Dataset Information

Array-CGH and Next-generation sequencing of duplication CNVs reveals that most are tandem and some disrupt genes at breakpoints

ABSTRACT: Interpreting the genomic and phenotypic consequences of copy number variation (CNV) is essential to understand the etiology of genetic disorders. Whereas deletion CNVs obviously lead to haploinsufficiency, duplications may cause disease through triplosensitivity, gene disruption, or gene fusion at breakpoints. The mutational spectrum of duplications has been studied at certain loci and in some cases these copy number gains are complex chromosome rearrangements involving triplications and/or inversions. However, the organization of clinically relevant duplications throughout the genome has not been investigated on a large scale. Here, we fine mapped 184 germline duplications (14.7 kb-25.3 Mb; median 532 kb) ascertained from individuals referred for diagnostic cytogenetics testing. We performed next-generation sequencing (NGS) and whole-genome sequencing (WGS) to sequence 130 breakpoints from 112 subjects with 119 CNVs and found that most (83%) were tandem duplications in direct orientation. The remainder were triplications embedded within duplications (8.4%), adjacent duplications (4.2%), insertional translocations (2.5%), or other complex rearrangements (1.7%). In addition, we predicted six in-frame fusion genes at sequenced duplication breakpoints. Four gene fusions were formed by tandem duplications, one by two interconnected duplications, and one by duplication inserted at another locus. These novel fusion genes could be related to clinical phenotypes and warrant further study. Though most duplications are positioned head-to-tail adjacent to the original locus, those that are inverted, triplicated, or inserted can disrupt or fuse genes in a manner that may not be predicted by conventional copy number analysis. Thus, interpreting the genetic consequences of duplication CNVs requires breakpoint-level analysis.

ORGANISM(S): Homo sapiens

PROVIDER: GSE62657 | GEO | 2014/10/25

SECONDARY ACCESSION(S): PRJNA264832

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

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

Array-CGH and Next-generation sequencing of duplication CNVs reveals that most are tandem and some disrupt genes at breakpoints

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets