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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.

Background and aims: Alagille syndrome (ALGS) is a multisystem disorder, characterized by cholestasis. Existing outcome data are largely derived from tertiary centers, and real-world data are lacking. This study aimed to elucidate the natural history of liver disease in a contemporary, international cohort of children with ALGS. Approach and results: This was a multicenter retrospective study of children with a clinically and/or genetically confirmed ALGS diagnosis, born between January 1997 and August 2019. Native liver survival (NLS) and event-free survival rates were assessed. Cox models were constructed to identify early biochemical predictors of clinically evident portal hypertension (CEPH) and NLS. In total, 1433 children (57% male) from 67 centers in 29 countries were included. The 10 and 18-year NLS rates were 54.4% and 40.3%. By 10 and 18 years, 51.5% and 66.0% of children with ALGS experienced >= 1 adverse liver-related event (CEPH, transplant, or death). Children (>6 and <= 12 months) with median total bilirubin (TB) levels between >= 5.0 and <10.0 mg/dl had a 4.1-fold (95% confidence interval [CI], 1.6-10.8), and those >= 10.0 mg/dl had an 8.0-fold (95% CI, 3.4-18.4) increased risk of developing CEPH compared with those 10.0 mg/dl were associated with a 4.8 (95% CI, 2.4-9.7) and 15.6 (95% CI, 8.7-28.2) increased risk of transplantation relative to <5.0 mg/dl. Median TB <5.0 mg/dl were associated with higher NLS rates relative to >= 5.0 mg/dl, with 79% reaching adulthood with native liver (p < 0.001). Conclusions: in this large international cohort of ALGS, only 40.3% of children reach adulthood with their native liver. A TB <5.0 mg/dl between 6 and 12 months of age is associated with better hepatic outcomes. These thresholds provide clinicians with an objective tool to assist with clinical decision-making and in the evaluation of therapies., This study received funding support from the following agencies: The Alagille Syndrome Alliance, Mirum Pharmaceuticals Inc. and Albireo Pharma, Inc. who provided unrestricted educational grants to the Hospital for Sick Children (SickKids Foundation). The study sponsors were not involved in the conduct of the research study or preparation of the manuscript.

Objective To assess long term graft and patient survival after donor liver retransplantation in children in Australia and New Zealand during 1986–2017; to determine the factors that influence survival. Design Retrospective cohort analysis (registry data). Setting, participants Australia and New Zealand Liver Transplant Registry data for all liver retransplantations in children (under 18 years of age), 1986–2017, in all four paediatric and six adult liver transplantation centres in the two countries. Main outcome measures Graft and patient survival at one, 5, 10 and 15 years. Results 142 liver retransplantations were undertaken in children (59 during 1986–2000, 83 during 2001–2017). Kaplan–Meier survival analysis indicated that survival was significantly greater during 2001–2017 than 1986–2000 (P < 0.001). During 2001–2017, graft survival one year after retransplantation was 84%, at 5 years 75%, at 10 years 70%, and at 15 years 54%; patient survival was 89% at one year, 87% at 5 years, 87% at 10 years, and 71% at 15 years. Median time between transplantations was 0.2 years (IQR, 0.03–1.4 years) during 1986–2000, and 1.8 years (IQR, 0.1–6.8 years) during 2001–2017 (P = 0.002). The proportion of graft failures that involved split grafts was larger during 2001–2017 (35 of 83, 42%) than 1986–2000 (10 of 59, 17%). Graft type, cause of graft failure, and number of transplants did not influence survival following retransplantation. Conclusion Survival for children following retransplantation is excellent. Graft survival is similar for split and whole grafts. Children on the liver waiting list requiring retransplantation should have the same access to donor grafts as children requiring a first transplant.