Pearls & Oy-sters: Whole-Genome Sequencing in Critically Ill Neurologic Patient Leads to Diagnosis With Treatment Implications

Many adult patients with a history of seizures and global developmental delay do not have an identified etiology for their epilepsy. Rapid whole-genome sequencing (rWGS) can be used to identify a genetic etiology in critically ill patients to provide actionable interventions. In this case, a 27-year-old patient with a history of epilepsy, global developmental delay, and intellectual disability presented with altered mental status and new abnormal movements. The patient acutely declined over the course of 24-48 hours of presentation, including nonconvulsive status epilepticus leading to intubation for airway protection, 2 episodes of ventricular tachycardia requiring synchronized cardioversion, and 1 episode of supraventricular tachycardia. The patient was found to be in metabolic crisis. Metabolic workup and rapid whole-genome sequencing were sent. Patient was treated with 10% dextrose in normal saline and a mitochondrial cocktail. She received treatment with ammonia scavengers and hemodialysis with resolution of metabolic crisis. rWGS found a homozygous pathogenic variant in TANGO2 and a de novo pathogenic variant in KCNQ1, ultimately leading to the creation of a metabolic emergency protocol and implantable cardioverter defibrillator placement. This case highlights the use of rWGS in an acutely ill patient leading to actionable interventions. It also highlights the utility and importance of genetic sequencing in reevaluation of adult neurologic patients.