Moroccan Experience of Targeted Screening for Inborn Errors of Metabolism by Tandem Mass Spectrometry

Background: Expanded newborn screening using tandem mass spectrometry (MS/MS) for inborn errors of metabolism (IEM), such as organic acidemias (OAs), fatty acid oxidation disorders (FAODs), and amino acid disorders (AAs), is increasingly popular but has not yet been introduced in Africa. With this study, we aim to establish the disease spectrum and frequency of inborn errors of OAs, FAODs, and AAs in Morocco. Methods: Selective screening was performed among infants and children suspected to be affected with IEM between 2016 and 2021. Amino acids and acylcarnitines spotted on filter paper were analyzed using MS/MS. Results: Out of 1178 patients with a clinical suspicion, 137 (11.62%) were diagnosed with IEM, of which 121 (88.3%) patients suffered from amino acids disorders, 11 (8%) were affected by FAOD, and 5 (3.7%) by an OA. Conclusions: This study shows that various types of IEM are also present in Morocco. Furthermore, MS/MS is an indispensable tool for early diagnosis and management of this group of disorders.