P725: Clinical exome sequencing towards molecular diagnosis: Insights and outcomes from 822 pediatric cases

Focusing on a set of 10 patients for whom there was high confidence in a small number of candidate genes, we used patient blood samples or fibroblasts to generate cDNA, PCR for genes of interest and generate full length reads using Oxford Nanopore Technologies single molecule sequencing.Results: Using this approach we identified probable pathogenic splicing events in two patient samples.We used not only existing transcriptomic annotations, but also publicly available short-and long-read sequencing data from control individuals to determine the rarity of the events detected.Furthermore, by enabling the prediction of both ORFs and protein structures, the availability of full-length reads greatly increased our ability to identify events expected to disrupt gene function rapidly.Conclusion: Taken together, our findings suggest that targeted long-read RNA-sequencing in patients who remain undiagnosed following extensive testing could be an important tool particularly when a treatable genetic diagnosis is being considered.