Rapid whole-genome sequencing (rWGS) has shown that genetic diseases are a common cause of infant mortality in neonatal intensive care units. Dried blood spots collected for newborn screening allow investigation of causes of infant mortality that were not diagnosed during life. Here, we present a neonate who developed seizures and encephalopathy on the third day of life that was refractory to antiepileptic medications. The patient died on day of life 16 after progressive respiratory failure and sepsis. The parents had lost two prior children after similar presentations, neither of whom had a definitive diagnosis. Postmortem rWGS of a dried blood spot identified a pathogenic homozygous frameshift variant in the SUOX gene associated with isolated sulfite oxidase deficiency (c.1390_1391del, p.Leu464GlyfsTer10). This case highlights that early, accurate molecular diagnosis has the potential to influence prenatal counseling and guide management in rare, genetic disorders and has added importance in cases of a strong family history and risk factors such as consanguinity.

Neonatal encephalopathy with seizures is a presentation in which rapid whole-genome sequencing (rWGS) has shown clinical utility and improved outcomes. We report a neonate who presented on the third day of life with seizures refractory to antiepileptic medications and neurologic and computerized tomographic findings consistent with severe generalized brain swelling. rWGS revealed compound heterozygous variants in the molybdenum cofactor synthesis gene, type 1A (MOCS1 c.*7 + 5G > A and c.377G > A); a provisional diagnosis of molybdenum cofactor deficiency on day of life 4. An emergency investigational new drug application for intravenous replacement of the MOCS1 product, cyclic pyranopterin monophosphate, was considered, but felt unsuitable in light of the severity of disease and delay in the start of treatment. The patient died on day of life 9 despite having a precise molecular diagnosis within the first week of life. This case illustrates that an rWGS-based molecular diagnosis within the first week of life may be insufficient to improve outcomes. However, it did inform clinical decision-making with regard to resuscitation and predicted long-term outcome. We suggest that to achieve optimal reductions in morbidity and mortality, rWGS must be implemented within a comprehensive rapid precision medicine system (CRPM). Akin to newborn screening (NBS), CRPM will have onboarding, diagnosis, and precision medicine implementation components developed in response to patient and parental needs. Education of health-care providers in a learning model in which ongoing data analyses informs system improvement will be essential for optimal effectiveness of CRPM.

Developmental and epileptic encephalopathy (DEE) due to SCN8A gene variants is characterized by drug-resistant early onset epilepsy associated with severe intellectual disability. Different seizure types have been reported, and a sequence of autonomic manifestations such as brady-/tachycardia, irregular breathing, and cyanosis. Nevertheless, an exhaustive video-polygraphic documentation is still lacking. In this study, we reviewed the ictal electroencephalograms (EEGs) of five patients with SCN8A-DEE followed-up at the Neuroscience Department at Bambino Gesù Children\'s Hospital in Rome. We identified generalized tonic seizure as the major seizure type at epilepsy onset. Seizure severity could vary from subtle to marked clinical manifestations, depending from the extent and groups of muscles involved and association with autonomic modifications. We found autonomic signs in 80% of seizures in our cases, and we were able to identify a stereotyped sequence of ictal events for most of seizures. Autonomic signs occurred in rapid sequence: flushing of the face, sometimes associated with sialorrhea, bradycardia, and hypopnea appeared within the first 1-2 s. Tachycardia, polypnea, perioral cyanosis, and pallor occurred later in the course of the seizure. Generalized tonic seizures are rarely described in other genetic epileptic conditions of early infancy because of ion channel mutations, such as in DEE due to KCNQ2 or SCN2A gene mutations, where seizures are most frequently reported as focal to bilateral tonic. Therefore, generalized symmetric tonic seizures with autonomic signs can be considered a clinical hallmark for diagnosis of SCN8A-related DEE and relevant for therapeutic implications.

Advancing the clinical utility of whole-exome sequencing (WES) for patients with suspected genetic disorders is largely driven by bioinformatics approaches that streamline data processing and analysis. Herein, we describe our experience with implementing a semiautomated and phenotype-driven WES diagnostic workflow, incorporating both the DRAGEN pipeline and the Exomiser variant prioritization tool, at an academic children\'s hospital with an ethnically diverse pediatric patient population. We achieved a 41% molecular diagnostic rate for 66 duo-, quad-, or trio-WES cases, and 28% for 40 singleton-WES cases. Preliminary results were returned to ordering physicians within 1 wk for 12 of 38 (32%) probands with positive findings, which were instrumental in guiding the appropriate clinical management for a variety of patients, especially in critical care settings. The semiautomated and streamlined WES workflow also enabled us to identify novel variants in candidate disease genes in patients with developmental delay and autism and immune disorders and cancer, including ANK2, BPTF, BCL11A, FOXN1, PLAA, ATRX, DNAJC21, and RAD50 Together, we demonstrated the implementation of a streamlined WES workflow that was successfully applied for both clinical and research purposes.

The SCN8A gene encodes the sodium voltage-gated channel alpha subunit 8. Mutations in this gene have been associated with early infantile epileptic encephalopathy type 13. With the use of whole-exome sequencing, a de novo missense mutation in SCN8A was identified in a 4-yr-old female who initially exhibited symptoms of epilepsy at the age of 5 mo that progressed to a severe condition with very little movement, including being unable to sit or walk on her own.