Isovaleric acidemia (IVA, OMIM #243500) is an autosomal recessive inborn error of leucine metabolism caused by homozygous or compound heterozygous variants in the isovaleryl-CoA dehydrogenase gene (IVD; OMIM *607036) on chromosome 15q15 (1). The gene discussed is IVD; the disease is isovaleric acidemia.