Distinct diagnostic trajectories in NBAS-associated acute liver failure highlights the need for timely functional studies.

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.

Epidemiology and outcomes of peritonitis in children on peritoneal dialysis in Australasia.

Peritonitis is a common complication and major cause of morbidity in children on peritoneal dialysis. In this retrospective longitudinal study, we analysed data retrieved from the Australian and New Zealand Dialysis and Transplant Registry (ANZDATA) on 167 patients aged less than 18 years of age who were treated with peritoneal dialysis during the period from October 2003 to December 2007. During this period there were 100 episodes of peritonitis in 57 patients (0.71 episodes/patient-year), with Gram-positive organisms most commonly isolated (44%). Peritonitis occurred frequently in the first 6 months after starting dialysis, with survival analysis showing peritonitis-free survival rates of 72%, 56% and 36% at 6 months, 1 year and 2 years respectively. Age was a weak predictor of peritonitis on univariate analysis, but previous peritonitis was the only significant predictor in a multivariate Cox proportional hazards model (adjusted hazard ratio 2.02; 95% CI: 1.20 to 3.40, p = 0.008). Peritonitis episodes infrequently resulted in relapse (5%), recurrence (7%) or the need for either temporary or permanent haemodialysis (5% and 7% respectively) and there were no patient deaths directly attributable to peritonitis. Compared with single organism peritonitis, polymicrobial peritonitis was not associated with any statistically significant differences in outcome. Further prospective studies are required to determine the most appropriate prophylactic measures and antibiotic regimens for use in pediatric patients.