Diagnostic utility of clinical genome reanalysis in rare pediatric disorders using long-read sequencing

More than half of presumed genetic disease cases remain undiagnosed following exome and/or short-read genome sequencing (SR-GS). Long-read genome sequencing (LR-GS) has emerged as a promising next step for uncovering etiologies missed by current standard-of-care SR genetic testing. However, structural variant (SV) interpretation remains a major challenge in LR-GS clinical pipelines, owing to limitations in SV call reliability, population allele frequency estimation, and evaluation of functional impact. To further develop strategies for the effective clinical use of LR-GS, we performed LR-GS using PacBio HiFi technology on 20 families with developmental disorders of suspected genetic origin and prior negative or inconclusive genetic testing (including exome and/or genome sequencing). Analysis was performed using a comprehensive pipeline integrating phased assembly– and read-based variant calling with LR-GS population allele frequency filtering. Phenotype-driven variant prioritization using Human Phenotype Ontology (HPO) terms was performed using a combination of tertiary analysis solutions, including publicly (SvAnna) and commercially (Illumina Emedgene) available tools. Definitive diagnostic findings were identified in 1/20 (5%) families. Variants of suspicious diagnostic significance were identified in 6/20 (30%). All findings of diagnostic significance were clinically confirmed using the proband’s prior clinical SR sequencing results, demonstrating the value of reanalysis and highlighting differences in clinical interpretation. One case harbored a homozygous ~50 kb deletion of initial interest that was only detected with LR-GS; however, it was ruled inconclusive based on frequency data from LR-GS population databases, underscoring the necessity of population filtering for structural variant clinical interpretation. Collectively, the observed increase in diagnostic yield (by 35% including suspicious findings) in this exome-/SR-GS-negative clinical cohort was driven primarily by genome reanalysis rather than identification of variants unique to LR-GS data. Additional functional studies are necessary to elucidate the clinical relevance of suspicious findings.

• Type: Whole Genome Sequencing
• Archiver: European Genome-phenome Archive (EGA)