Clinical, Biochemical and Molecular Characterisation of Newborns With Fatty Acid β-Oxidation Disorders: Novel Variants in the ACADM, ACADVL and SLC22A5 Genes.

In this study, we aimed to assess clinical, laboratory and molecular features of newborns with clinical suspicion for systemic primary carnitine deficiency (CUD), medium-chain acyl-CoA dehydrogenase deficiency (MCADD) and very long-chain acyl-CoA dehydrogenase deficiency (VLCADD). The implementation of newborn screening programs for fatty acid β-oxidation disorders (FAODs) has changed the natural course of these diseases, facilitating the initiation of preventive or therapeutic measures for affected newborns shortly after birth. This study included 94 newborns who were admitted between 2016 and 2023 because of biochemical signs of CUD, MCADD and VLCADD, and provided clinical, biochemical and genotypic data. Definitive molecular diagnosis confirmed that 16/94 newborns (17%) were true positives of the NBS, and 17 novel variants were detected in SLC22A5, ACADM and ACADVL genes. We assessed the clinical evolution of patients over time. This study expands the genotypic spectrum of SLC22A5, ACADM and ACADVL and highlights the role of genetics in identifying and correctly characterising FAODs.