RESUMEN
Variants of uncertain significance (VUS) are commonly found following genomic sequencing, particularly in ethnically diverse populations that are underrepresented in large population databases. Functional characterization of VUS may assist in variant reclassification, however these studies are not readily available and often rely on research funding and good will. We present four individuals from three families at different stages of their diagnostic trajectory with recurrent acute liver failure (RALF) and biallelic NBAS variants, confirmed by either trio analysis or cDNA studies. Functional characterization was undertaken, measuring NBAS and p31 levels by Western blotting, demonstrating reduced NBAS levels in two of three families, and reduced p31 levels in all three families. These results provided functional characterization of the molecular impact of a missense VUS, allowing reclassification of the variant and molecular confirmation of NBAS-associated RALF. Importantly, p31 was decreased in all individuals, including an individual with two missense variants where NBAS protein levels were preserved. These results highlight the importance of access to timely functional studies after identification of putative variants, and the importance of considering a range of assays to validate variants whose pathogenicity is uncertain. We suggest that funding models for genomic sequencing should consider incorporating capabilities for adjunct RNA, protein, biochemical, and other specialized tests to increase the diagnostic yield which will lead to improved medical care, increased equity, and access to molecular diagnoses for all patients.
RESUMEN
Although rapid genomic sequencing (RGS) is improving care for critically ill children with rare disease, it also raises important ethical questions that need to be explored as its use becomes more widespread. Two such questions relate to the degree of consent that should be required for RGS to proceed and whether it might ever be appropriate to override parents' decisions not to allow RGS to be performed in their critically ill child. To explore these questions, we first examine the legal frameworks on securing consent for genomic sequencing and how they apply to the specific context of RGS for critically ill children. We then use a tool from clinical ethics, the Zone of Parental Discretion, to explore two case studies and identify under which circumstances it might be appropriate for parental refusal of RGS to be overridden. We argue that RGS may be a context where, in addition to assessing the complexity of the test offered, it is ethically appropriate to consider an effect on patient outcomes when deciding the degree of consent required. We also suggest that there are some contexts where it may be ethically justified to perform RGS, even when it is actively against the wishes of the parents. More work is needed to examine exactly how 'time-sensitive' exceptions to current guidance on consent for genomic sequencing could be formulated and operationalised for RGS for critically ill-children.