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Transient multifocal genomic crisis creating chromothriptic and non-chromothriptic rearrangements in prezygotic testicular germ cells.

ABSTRACT: BACKGROUND:The co-occurrence of multiple de novo copy number variations (CNVs) is a rare phenomenon in the human genome. Recently, an "organismal CNV mutator phenotype" has been reported to result in transient genomic instability introducing multiple de novo CNVs in primary oocytes and early-stage zygotes. These findings opened a new area of human genome research. METHODS:We performed genome-wide copy number analysis for ~?2100 individuals with various congenital defects. Furthermore, extensive molecular analyses, including synthetic long-read whole-genome sequencing and haplotype-phasing, were carried out for an individual with multiple de novo CNVs. RESULTS:A boy was found to have de novo rearrangements on five chromosomes. The rearrangements comprised simple duplication and inversion as well as chaotic changes, all of which affected paternally derived chromosomes. Postzygotic genomic instability was ruled out. The duplicated regions on 6q and 13q contained both diallelic and triallelic loci, indicating that the genomic rearrangements were initially created during premeiotic mitosis and subsequently modified by physiological cross-over during meiosis I. Breakpoints of the rearrangements were indicative of non-homologous end joining, replication-based errors, and/or chromothripsis. The mutagenic event was independent of specific local DNA motifs or de novo point mutations, but may be driven by spermatogenesis-specific factors. CONCLUSIONS:These results indicate that during spermatogenesis, a transient multifocal genomic crisis can introduce several chromothriptic and non-chromothriptic changes into the genome. These findings broaden the concept of the "organismal CNV mutator phenotype". This study provides insights into mechanisms for altering the global chromosomal architecture of human embryos.

SUBMITTER: Hattori A

PROVIDER: S-EPMC6540402 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Transient multifocal genomic crisis creating chromothriptic and non-chromothriptic rearrangements in prezygotic testicular germ cells.

Hattori Atsushi A Okamura Kohji K Terada Yumiko Y Tanaka Rika R Katoh-Fukui Yuko Y Matsubara Yoichi Y Matsubara Keiko K Kagami Masayo M Horikawa Reiko R Fukami Maki M

BMC medical genomics 20190528 1

<h4>Background</h4>The co-occurrence of multiple de novo copy number variations (CNVs) is a rare phenomenon in the human genome. Recently, an "organismal CNV mutator phenotype" has been reported to result in transient genomic instability introducing multiple de novo CNVs in primary oocytes and early-stage zygotes. These findings opened a new area of human genome research.<h4>Methods</h4>We performed genome-wide copy number analysis for ~ 2100 individuals with various congenital defects. Furtherm ...[more]

PMID: 31138192

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Project description:BackgroundTesticular germ cell tumors (TGCTs) account for 1-2% of all tumors in young and middle aged men. A 75-fold increase in TCGT development has been reported for monozygotic (MZ) twins. Therefore, the occurrence of simultaneous tumors in MZ twins emphasizes the importance of genetic factors that influence the risk of developing these tumors. Genomic screening was performed for one family containing MZ twins with testicular germ cell tumors, in order to define alterations associated with risk of tumor development.MethodsCopy number alterations were evaluated using array-CGH (4x44K, Agilent Technologies) in one seminoma and one embryonal carcinoma (EC) from MZ twins. In addition, genomic alterations from the tumors and peripheral blood cells of the twins were compared to the parental genomes via their peripheral blood cells.ResultsEmbryonal carcinoma (Twin-1 t) presented a lower frequency of genomic alterations compared to the seminoma (Twin-2 t). One minimal common region of loss was observed in 9p13.1-p12 in the comparison between DNA from blood samples for Twin-1 and Twin-2. In this region is mapped the CNTNAP3 gene which was confirmed as involved in losses by qPCR. Comparative analysis of novel CNVs between the Twin-1 t and Twin-2 t showed five minimal common regions involving gain at chromosomes 12 (12p12.3-p11.1 and 12p13.33-p12.3), while losses were observed at 10p15.3-p15.2, 13q21.1-q21.2 and 15q11.1-q11.2. In addition, one exclusive rare copy number alteration was detected in Twin-1 t and Twin-2 t, and 19 novel alterations were identified in the Twin-2 t.ConclusionDistinct genomic profiles for MZ twins with phenotypically different TGCT were described. Of particular interest, 12p gains were detected exclusively in tumor samples. In peripheral blood samples, loss of 9p13.1-p12 was the unique novel CNV shared by the twins, confirming the involvement of CNTNAP3 gene in TGCTs development. Although similar CNV profiles were shared by both the peripheral blood and tumor samples of the twins, tumor-specific CNV loci were identified for seminoma and non-seminomatous tumors. These findings suggest the presence of de novo germline structural alterations and TGCT predisposition.

Dataset Information

Transient multifocal genomic crisis creating chromothriptic and non-chromothriptic rearrangements in prezygotic testicular germ cells.

Publications

Transient multifocal genomic crisis creating chromothriptic and non-chromothriptic rearrangements in prezygotic testicular germ cells.

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