Alex Mowat Prize: Best Hepatology Presentation
Study of acute liver failure in children using targeted next generation sequencing technology
Robert Hegarty (1,2), Melissa Sambrotta (2), Philippa Gibson (2), Sandra Strautnieks (1), Tassos Grammatikopoulos (1,2) and Richard Thompson (1,2).
(1) King's College Hospital NHS Foundation Trust ; (2) King's College London
Acute liver failure (ALF) in children is rare but, without treatment, a potentially fatal condition. Whilst monogenic, metabolic diseases form the largest diagnostic category, diagnosis can be difficult such that in up to 43% of cases the cause remains undetermined.
The study’s aim was to identify undiagnosed, monogenic causes of ALF using targeted, next generation sequencing (NGS) technology and report on its clinical utility. The primary objective was to identify undiagnosed monogenic diseases in children who received a diagnosis of indeterminate ALF and to describe their characteristics. The secondary objectives were to: (1) provide the research foundation to construct a diagnostic, genetic panel using targeted NGS technology for future children with indeterminate ALF; (2) identify and characterise children who have a mutation in NBAS (or any other novel gene).
Children < 10 years of age admitted to our centre with ALF who had stored Biobank blood samples were included in the study. An NGS custom panel of 64 candidate genes, known to cause ALF and / or metabolic liver disease, was constructed using the online Agilent SureDesign tool. The Agilent SureSelect QXT kit was used for the library generation and preparation of samples.
Sequencing was performed on genomic DNA extracted from blood samples of 41 children (male = 23) with a median age, at presentation with ALF, of 2.2 years (range: 7 days to 8.6 years). The depth of coverage was > 30X in > 99.9% of targeted regions. The total number of non-synonymous variants with a minor allele frequency of < 1 % was 69 (29 children) in 40 genes: biallelic variants = 9 (8 children) in 7 genes; monoallelic = 60 (27 children) in 40 genes. Biallelic variants, including 1 child with a copy number variant, were found in the following genes (number of children): NBAS (3); TWINK (1); CPT1A (1); SUCLG1 (1); POLG (1); MPV17 (1); DLD (1). Amongst these 8 children, 5 had received emergency liver transplantation and all patients were alive at last follow up.
Biallelic variants of varying pathogenicity were found in 8/41 children (20%) whereby variants in NBAS and genes encoding mitochondrial proteins were the most common findings. Further studies are required to evaluate the contribution of these genetic variants to ALF. Nevertheless, decision for liver transplantation may have been influenced if these genetic results were available at the time of ALF. In the future, a rapid sequencing NGS workflow could aid in reaching a timely diagnosis and clinical decision making.