Purpose: The study aimed to define the genotypic and phenotypic spectrum of reversible acute liver failure (ALF) of infancy resulting from biallelic pathogenic TRMU variants and to determine the role of cysteine supplementation in its treatment. Methods: Individuals with biallelic (likely) pathogenic variants in TRMU were studied through an international retrospective collection of de-identified patient data. Results: In 62 individuals, including 30 previously unreported cases, we described 48 (likely) pathogenic TRMU variants, of which, 18 were novel. Of these 62 individuals, 42 were alive at a median age of 6.8 (0.6-22) years after a median follow up of 3.6 (0.1-22) years. The most frequent finding, occurring in all but 2 individuals, was liver involvement. ALF occurred only in the first year of life and was reported in 43 of 62 individuals, 11 of whom received liver transplantation. Loss-of-function TRMU variants were associated with poor survival. Supplementation with at least 1 cysteine source, typically N-acetylcysteine, improved survival significantly. Neurodevelopmental delay was observed in 11 individuals and persisted in 4 of the survivors, but we were unable to determine whether this was a primary or a secondary consequence of TRMU deficiency. Conclusion: In most patients, TRMU-associated ALF is a transient, reversible disease and cysteine supplementation improved survival.
FörderungenUK NIHR Biomedical Research Centre for Ageing and Age-related Disease award Lily Foundation Medical Research Council Medical Research Council International Centre for Genomic Medicine in Neuromuscular Disease Mitochondrial Disease Patient Cohort (United Kingdom) Wellcome Trust Centre for Mitochondrial Research Saol Therapeutics Optimizing diagnostics and treatment for patients with mitochondrial diseases FWF PTC Therapeutics Courage for a Cure Foundation Mervar Foundation Frontiers of Congenital Disorders of Glycosylation Consortia (FCDGC) North American Mitochondrial Disease Consortia National Institutes of Health European Reference Network for Hereditary Metabolic Disorders (MetabERN) MitoCanada Astellas Pharma Inc. UK NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children King Salman Center for Disability Research Bavarian State Ministry of Health and Care BMBF (German Federal Ministry of Education and Research) Victorian Government's Operational Infrastructure Support program National Health and Medical Research Council (NHMRC) New South Wales Office of Health and Medical Research Council Sydney Genomics Collaborative grant Pathological Society