BinDel: software tool for detecting clinically significant microdeletions in low-coverage WGS-based NIPT samples

Clinically pathogenic chromosomal microdeletions causing genetic disorders such as DiGeorge syndrome are rare genetic aberrations that can cause clinically relevant fetal and childhood developmental deficiencies. Clinical severity of such deficiencies depend on the exact genomic location and genes affected by the fetal chromosomal aberration. Here we present the BinDel, a novel region-aware microdeletion detection software package developed to infer clinically relevant microdeletion risk in low-coverage whole-genome sequencing NIPT data. To test BinDel, we quantified the impact of sequencing coverage, fetal DNA fraction, and region length on microdeletion risk detection accuracy. We also estimated BinDel accuracy on known microdeletion samples and clinically validated aneuploidy samples. BinDel identified each positive control sample as high risk. We also determined that it is critical to take into account that the sample with a detected high microdeletion risk does not have a full chromosome aneuploidy, as the latter can cause erroneous high microdeletion risk findings. We observed that lower sequencing coverage resulted in reduced microdeletion detection accuracy, and higher fetal fractions considerably increased the microdeletion detection accuracy, with coverage becoming increasingly relevant as fetal DNA fraction decreased. In conclusion, we developed an R package-based software tool BinDel for inferring fetal microdeletion risks, which accurately identified all positive control samples with microdeletion or -duplication aberrations as high-risk samples. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was supported by Enterprise Estonia (grants No. EU48695 and EU53935); Estonian Research Council (grant No. PRG1076) and Horizon 2020 innovation grant (ERIN, grant no. EU952516). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was performed with the written informed consent from the participants and with approval of the Research Ethics Committee of the University of Tartu (#352/M-12). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors