Clinico-radiological features, molecular spectrum, and identification of prognostic factors in developmental and epileptic encephalopathy due to inosine triphosphate pyrophosphatase (ITPase) deficiency.
Developmental and epileptic encephalopathy 35 (DEE 35) is a severe neurological condition caused by biallelic variants in ITPA, encoding inosine triphosphate pyrophosphatase, an essential enzyme in purine metabolism. We delineate the genotypic and phenotypic spectrum of DEE 35, analysing possible predictors for adverse clinical outcome. We investigated a cohort of 28 new patients and reviewed previously described cases, providing a comprehensive characterization of 40 subjects. Exome sequencing was performed to identify underlying ITPA pathogenic variants. Brain MRI scans were systematically analyzed to delineate the neuroradiological spectrum. Survival curves according to the Kaplan-Meier method and Log-Rank test were used to investigate outcome predictors in different subgroups of patients. We identified 18 distinct ITPA pathogenic variants, including 14 novel variants, and 2 deletions. All subjects showed profound developmental delay, microcephaly, and refractory epilepsy followed by neurodevelopmental regression. Brain MRI revision revealed a recurrent pattern of delayed myelination and restricted diffusion of early myelinating structures. Congenital microcephaly and cardiac involvement were statistically significant novel clinical predictors of adverse outcome. We refined the molecular, clinical, and neuroradiological characterization of ITPase deficiency, and identified new clinical predictors which may have a potentially important impact on diagnosis, counselling, and follow-up of affected individuals. This article is protected by copyright. All rights reserved.
FörderungenGerman Network for Mitochondrial Disorders (mitoNET) Muscular Dystrophy Association (MDA USA) Muscular Dystrophy UK (MDUK) Sparks GOSH Charity Brain Research UK MSA Trust Ataxia UK Rosetree Trust National Institute for Health Research University College London Hospitals Biomedical Research Centre National Institute for Health Research (NIHR) Oxford Biomedical Research Centre based at Oxford University Hospitals NHS Trust University of Oxford Wellcome Trust German Bundesministerium fur Bildung und Forschung (BMBF) Erasmus MC Human Disease Model Award 2018 Erasmus MC Fellowship 2017 Netherlands Organization for Scientific Research (ZonMW Veni) CERCA Programme AGAUR 2017 Generalitat de Catalunya (URDCATproject ) Instituto de Salud Carlos III (Ministerio de Ciencia e Innovacion, Spain) Centro de Investigacion Biomedica en Red de Enfermedades Raras (CIBERER) Instituto de Salud Carlos III (European Regional Development Fund "A way to make Europe") MRC