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Microdeletions of chromosomal region 2q23.1 that disrupt MBD5 (methyl-CpG-binding domain protein 5) contribute to a spectrum of neurodevelopmental phenotypes; however, the impact of this locus on human psychopathology has not been fully explored. To characterize the structural variation landscape of MBD5 disruptions and the associated human psychopathology, 22 individuals with genomic disruption of MBD5 (translocation, point mutation and deletion) were identified through whole-genome sequencing or cytogenomic microarray at 11 molecular diagnostic centers. The genomic impact ranged from a single base pair to 5.4 Mb. Parents were available for 11 cases, all of which confirmed that the rearrangement arose de novo. Phenotypes were largely indistinguishable between patients with full-segment 2q23.1 deletions and those with intragenic MBD5 rearrangements, including alterations confined entirely to the 5′-untranslated region, confirming the critical impact of non-coding sequence at this locus. We identified heterogeneous, multisystem pathogenic effects of MBD5 disruption and characterized the associated spectrum of psychopathology, including the novel finding of anxiety and bipolar disorder in multiple patients. Importantly, one of the unique features of the oldest known patient was behavioral regression. Analyses also revealed phenotypes that distinguish MBD5 disruptions from seven well-established syndromes with significant diagnostic overlap. This study demonstrates that haploinsufficiency of MBD5 causes diverse phenotypes, yields insight into the spectrum of resulting neurodevelopmental and behavioral psychopathology and provides clinical context for interpretation of MBD5 structural variations. Empirical evidence also indicates that disruption of non-coding MBD5 regulatory regions is sufficient for clinical manifestation, highlighting the limitations of exon-focused assessments. These results suggest an ongoing perturbation of neurological function throughout the lifespan, including risks for neurobehavioral regression. [ABSTRACT FROM AUTHOR]

What's already known about this topic?Chromothripsis is a recently described phenomenon whereby a single catastrophic event leads to multiple chromosome breaks and subsequent repair through nonhomologous end joining. The result can present karyotypically as a complex rearrangement and occurs both congenitally and in cancer cells. What does this study add?We report, to our knowledge, the first case of congenital chromothripsis uncovered prenatally through a combination of G ‐ banded karyotype analysis and whole ‐ genome sequencing by jumping libraries. The G ‐ banded karyotype initially suggested the involvement of five chromosomes and six breakpoints. Whole ‐ genome sequencing further resolved this event to include nine total breakpoints that disrupt seven independent genes, all in the presence of a normal microarray result. This emphasizes the complementarity that whole ‐ genome sequencing can provide to the initial karyotype analysis as a reflex test when a rearrangement is detected. We also discuss the dilemma of prognosis with this finding. [ABSTRACT FROM AUTHOR]