Purpose: Early diagnosis and timely initiation of treatment have been shown to be crucial to improve clinical outcomes in individuals with inherited metabolic diseases (IMDs). However, comprehensive data on the diagnostic process and the potential diagnostic delay in IMDs are scarce. This study aims to systematically investigate the diagnostic process in IMDs.
Methods: Data were obtained from the Unified European registry for Inherited Metabolic Diseases (U-IMD), the patient registry of the European Reference Network MetabERN.
Results: Data were available for 3747 individuals with confirmed diagnosis of one of 345 IMDs. Median age at symptom onset was 120 days. The majority of participants were diagnosed after presenting with symptoms, median diagnostic delay in this group was 270 days, with 47.6% experiencing a diagnostic delay of at least 1 year. Diagnostic delay did not seem to have changed substantially within the last 2 decades in this cohort; however, it varied greatly among single IMDs and different IMD disease groups.
Conclusion: Diagnostic delay and concomitantly delayed start of specific therapies is a significant risk of poor outcome for individuals with IMDs, highlighting the urgent need to expand newborn screening programs and to establish (ultra-)rapid genome sequencing in critically ill children.
Keywords: Diagnostic odyssey; European Reference Network for Hereditary Metabolic Disorders (MetabERN); Inherited metabolic diseases; Unified European Registry for Inherited Metabolic Disorders (U-IMD).
Copyright © 2026 The Authors. Published by Elsevier Inc. All rights reserved.