Dealing With Unspecific Clinical Phenotypes in Molecular Autopsy - HPO-Driven Whole Exome Sequencing Analysis Versus Gene Panel Testing

Abstract

Background: Molecular autopsy represents an efficient tool to save the diagnosis in up to one-third of sudden unexplained death (SUD). A defined gene panel is usually used for the examination. Alternatively, it is possible to carry out a comprehensive genetic assessment (Whole Exome Sequencing, WES), which also identifies rare, previously unknown variants. The disadvantage is that a dramatic number of variants must be assessed to identify the causal variant. To improve the evaluation of WES, the Human Phenotype Ontology (HPO) annotation is used internationally for deep phenotyping in the field of rare disease. However, a HPO-based evaluation of WES in SUD has not been described before.Methods: We performed WES in tissue samples from 16 people after SUD. Instead of a fixed gene panel, we defined a set of HPO terms and thus created a flexible “virtual gene panel”, with the advantage, that recently identified genes are automatically associated by HPO terms in the HPO database.Results: We obtained a median value of 68,947 variants per sample. Stringent filtering ended up in a median value of 276 variants per sample. Using the HPO-driven virtual gene panel we developed an algorithm that prioritized 1.4% of the variants. Variant interpretation resulted in eleven potentially causative variants in 16 individuals. Conclusion: Our data introduce an effective diagnostic procedure in molecular autopsy of SUD with a non-specific clinical phenotype.