Long-chain 3-hydroxy acyl-CoA dehydrogenase deficiency (LCHADD; ORPHA: 5), caused by biallelic pathogenic variants in the HADHA gene (OMIM #609016), is a very rare autosomal recessive disease with the worldwide incidence of 1:62,000–1:250,000 [Joost et al. 2011]. The gene discussed is HADHA; the disease is long chain 3-hydroxyacyl-CoA dehydrogenase deficiency.