3-Hydroxy-3-methylglutaryl-CoA (HMG-CoA) Lyase deficiency (HMGLD) (OMIM 246450) is an autosomal recessive genetic disorder caused by homozygous or compound heterozygous variants in the <i>HMGCL</i> gene located on 1p36.11. The gene discussed is HMGCL; the disease is 3-hydroxy-3-methylglutaric aciduria.