Evaluation of Patients Diagnosed with Inherited Metabolic Diseases in Adulthood.

Objectives: Inherited metabolic diseases (IMDs) arise due to deficiencies in enzymes involved in metabolic pathways or other dysfunctions within these pathways, leading to a deficiency of specific end products or the toxic accumulation of intermediate metabolites. These diseases may present at any age with varying clinical courses. With advances in treatment options and increased awareness, IMDs are increasingly being diagnosed and managed in adulthood. This study aims to understand the clinical features and diagnostic processes of patients diagnosed with IMDs during adulthood and to raise awareness regarding these conditions. Methods: Medical records of adult patients diagnosed with IMDs between June 2022 and June 2024 were retrospectively reviewed. Patients were included if they were diagnosed with an IMD at or above the age of 18. Those diagnosed during childhood but transitioning to adulthood were excluded. Results: Twenty patients, aged 19-72 years (11 males, 9 females), were diagnosed with IMDs. The mean age of symptom onset was 30 years (range: 15-70 years), and the mean age of diagnosis was 37 years (range: 18-72 years). Diagnoses included Fabry disease (n=10, 20%), familial hypobetalipoproteinemia (FHBL) (n=3, 15%), and alkaptonuria (AKU) (n=2, 10%). Other diagnoses included Gaucher disease, Niemann-Pick disease type B, glycogen storage disease type IIIa (GSD IIIa), glycogen storage disease type XV (GSD XV), and cerebrotendinous xanthomatosis (CTX). Sixty-five percent of patients were identified via family screening, while 35% were diagnosed based on clinical findings supported by biochemical tests. Misdiagnoses before definitive IMD diagnosis included osteoarthritis, psoriatic arthritis, renal failure, heart failure, proteinuria, interstitial lung disease, hepatosteatosis, and nephrolithiasis. Disease-specific treatments were initiated and follow-ups were conducted. Conclusion: Chronic and mild phenotypes of certain IMDs may pose diagnostic challenges. Increased awareness among healthcare professionals and further studies focusing on differential diagnoses are critical to improving the detection and management of IMDs.