Analysis of copy number changes and complex rearrangements in patients with congenital abnormalities

Chromothripsis represents a novel phenomenon in the structural variation landscape of cancer genomes. Here, we analyzed the genomes of ten patients with congenital disease that were preselected to carry complex chromosomal rearrangements (CCRs) with more than two breakpoints. The rearrangements displayed unanticipated complexity resembling chromothripsis. We find that eight of them contain hallmarks of multiple clustered double-stranded DNA breaks (DSBs) on one or more chromosomes. In addition, nucleotide resolution analysis of 98 breakpoint-junctions indicates that break-repair involves non-homologous or microhomology mediated end-joining. We observed that these eight rearrangements are balanced or contain sporadic deletions ranging in size between a few hundred bp and several Mb. The two remaining complex rearrangements did not display signs of DSBs and contain duplications, indicative of rearrangement processes involving template-switching. Our work provides detailed insight in the characteristics of chromothripsis and supports a role for clustered DSBs driving some constitutional chromothripsis rearrangements. We analyzed five patient-parent trios with Illumina BeadChip arrays to test for (de novo) copy number variants and to analyze the parental origin of the complex rearrangements in these patients.