Hydroxymethylglutaric aciduria

Alternative names	3-hydroxy-3-methylglutaryl-CoA lyase deficiency HMG-CoA lyase deficiency
About the condition	Hydroxymethylglutaric aciduria is an organic acid disorder. It is a hereditary disease that is caused by a missing enzyme needed to convert protein into energy. There is also failure to produce ketone bodies.
Inheritance	Autosomal recessive
Year screening started in WA	2005
Incidence in Australia	Currently unknown
Enzyme defect	Deficiency of HMG-CoA lyase, which catalyses the final step of leucine degradation and plays a role in ketone formation.
Symptoms if untreated	Hypoketotic hypoglycaemia Metabolic acidosis Vomiting Lethargy, hypotonia Apnoea, seizures Hepatomegaly Coma and death possible
Metabolites on bloodspot screening	Increased hydroxymethylglutarylcarnitine (C5MeDC) and hydroxyisovalerylcarnitine (C5OH).
Diagnostic tests	Plasma acylcarnitine profile Urine organic acids HMGCL gene analysis
Treatment	High-carbohydrate, low-protein diet Carnitine supplementation Avoidance of fasting IV glucose during crisis episodes
Screening issues	None