3-Hydroxy-3-Methylglutaryl-CoA Lyase Deficiency

3-Hydroxy-3-methylglutaryl-CoA lyase deficiency, commonly known as HMG-CoA lyase deficiency, is a rare inborn error that affects ketogenesis and leucine catabolism. Symptoms usually appear in the first year of life and include metabolic acidosis with hypoketotic hypoglycemia, hyperammonemia, abnormal liver function tests, vomiting and hypotonia. Other signs are hepatomegaly, macrocephaly, and less frequently microcephaly, seizures, acute pancreatitis, dilated cardiomyopathy and arrhythmia. Abnormal cerebral white matter foci on MRI has also been reported. Without treatment, rapid progression to coma and death or permanent neurological damage may occur. With treatment, many patients do well; however recurrent metabolic decompensation continues to occur especially with prolonged fasting or intercurrent illness. This disorder is fatal in approximately 20% of cases with the symptoms becoming milder after childhood.

Tests Available

Forms and Documents

Test Details

  • Confirmation of biochemical diagnosis
  • Carrier testing
  • Prenatal diagnosis in at risk pregnancies
  • Capillary Sequencing


4-5 weeks
2-5 mL Blood - Lavender Top Tube
Oral Rinse (30-40 mL) | Buccal Swabs


  • 277.85 Disorders of fatty acid oxidation, Carnitine palmitoyltransferase deficiencies, Glutaric aciduria type II, Long chain 3-hydroxyacyl CoA dehydrogenase deficiency (LCHAD), Long chain/very long chain acyl CoA dehydrogenase deficiency, Medium chain acyl CoA dehydrogenase deficiency (MCAD), Short chain acyl CoA dehydrogenase deficiency (SCAD)
  • 270.3 Disturbances of branched-chain amino-acid metabolism, Disturbances of metabolism of leucine, isoleucine, and valine, Hypervalinemia Intermittent branched-chain ketonuria, Leucine-induced hypoglycemia, Leucinosis, Maple syrup urine disease
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  4. Menao et al., (2009) Hum Mutat 30:E520-9
  5. Pie et al., (2007) Mol Genet Metab 92:198-209