Analyses of breakpoint junctions of complex genomic rearrangements comprising multiple consecutive microdeletions by nanopore sequencing

J Hum Genet. 2020 Sep;65(9):735-741. doi: 10.1038/s10038-020-0762-6. Epub 2020 Apr 30.

Abstract

The widespread use of genomic copy number analysis has revealed many previously unknown genomic structural variations, including some which are more complex. In this study, three consecutive microdeletions were identified in the same chromosome by microarray-based comparative genomic hybridization (aCGH) analysis for a patient with a neurodevelopmental disorder. Subsequent fluorescence in situ hybridization (FISH) analyses unexpectedly suggested complicated translocations and inversions. For better understanding of the mechanism, breakpoint junctions were analyzed by nanopore sequencing, as a new long-read whole-genome sequencing (WGS) tool. The results revealed a new chromosomal disruption, giving rise to four junctions in chromosome 7. According the sequencing results of breakpoint junctions, all junctions were considered as the consequence of multiple double-strand breaks and the reassembly of DNA fragments by nonhomologous end-joining, indicating chromothripsis. KMT2E, located within the deletion region, was considered as the gene responsible for the clinical features of the patient. Combinatory usage of aCGH and FISH analyses would be recommended for interpretation of structural variations analyzed through WGS.

Publication types

  • Case Reports

MeSH terms

  • Chromosome Aberrations*
  • Chromosome Breakage
  • Chromosome Inversion
  • Comparative Genomic Hybridization / methods*
  • DNA Breaks, Double-Stranded
  • DNA Copy Number Variations
  • DNA End-Joining Repair
  • DNA-Binding Proteins / genetics*
  • Female
  • Genetic Association Studies
  • Genome, Human
  • Genomics / methods*
  • Humans
  • In Situ Hybridization, Fluorescence / methods*
  • Nanopore Sequencing
  • Neurodevelopmental Disorders / genetics*
  • Oligonucleotide Array Sequence Analysis
  • Sequence Inversion
  • Translocation, Genetic
  • Whole Genome Sequencing
  • Young Adult

Substances

  • DNA-Binding Proteins
  • KMT2E protein, human