Published 29 July 2020
Chromosomal insertions are thought to be rare structural rearrangements. In this study, we sequenced 16 cases with apparent simple insertions previously identified by karyotyping and/or chromosomal microarray analysis. Additional cryptic rearrangements were identified in 68.8% of the cases (11/16). Overall, our study provide molecular characterization of karyotypically apparent simple insertions, demonstrate previously underappreciated complexities, and evidence that chromosomal insertions are likely formed by nonhomologous end joining and/or microhomology-mediated replication-based DNA repair.