Paracentric inversion disrupting the SHANK2 gene

Abstract

In this study, we employed a multifaceted approach combining short-read whole genome sequencing (WGS) analyzed using Delly, cytogenomics using Bionano technology, and Sanger sequencing to identify the breakpoints of a balanced de novo paracentric inversion on chromosome 11, spanning approximately 64 Mb (inv11q13.3; q25). This inversion was discovered in a girl who presented with mild intellectual disability (ID), speech and language delays, a delay in motor development and attention deficit hyperactivity disorder (ADHD). Detailed analysis of the breakpoints revealed the disruption of two genes; SHANK2, which is critical for encoding a postsynaptic scaffolding protein at glutamatergic synapses in the brain, and LINC02714, a long non-coding RNA (lncRNA). Although SHANK2 is not listed in the OMIM database as a causative gene to this date, literature reports at least 21 cases where (likely) pathogenic variants in SHANK2 have been identified in patients with neurodevelopmental disorders (NDDs). A loss of function variant of the SHANK2 gene is in line with the clinical presentation of this patient. No additional genetic variants that could explain her phenotype were identified. In conclusion, by combining WGS, cytogenomics and Sanger sequencing techniques, we identified the exact breakpoints of a large inversion providing a likely molecular diagnosis for our patient.