Very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) (OMIM 201475), an autosomal recessive inborn error of metabolism, caused by pathogenic mutations in the ACADVL gene, is a mitochondrial long-chain fatty acid oxidation (lcFAO) disorder [1,2]. The gene discussed is ACADVL; the disease is very long chain acyl-CoA dehydrogenase deficiency.