A Comprehensive Iterative Approach is Highly Effective in Diagnosing Individuals who are Exome Negative

PURPOSE: Sixty-75% of individuals with rare and undiagnosed phenotypes remain undiagnosed after whole exome sequencing (ES). With standard ES reanalysis resolving 10–15% of the ES negatives, further approaches are necessary to maximize diagnoses in these individuals. METHODS: In 38 ES negative patients an individualized genomic-phenotypic approach was employed utilizing: A) Phenotyping; B) Reanalyses of FASTQ files, with innovative bioinformatics; C) Targeted molecular testing; D) Whole genome sequencing (WGS) and E) Conferring of clinical diagnoses when pathognomonic clinical findings occurred. RESULTS: Certain and Highly Likely diagnoses were made in 18/38 (47%) individuals, including identifying two new developmental disorders. The majority of diagnoses (>70%) were due to our bioinformatics, phenotyping and targeted testing identifying variants that were undetected or not prioritized on prior ES. WGS diagnosed 3/18 individuals, with structural variants not amenable to ES. Additionally, Tentative diagnoses were made in three (8%) and in five individuals (13%) candidate genes were identified. Overall, diagnoses/potential leads were identified in 26/38 (68%). CONCLUSIONS: Our comprehensive approach to ES negatives maximizes the ES and clinical data for both diagnoses and candidate gene identification, without WGS in the majority. This iterative approach is cost-effective and is pertinent to the current conundrum of ES negatives.