3-methylcrotonyl-CoA carboxylase (3-MCC) deficiency

Alternative name	3-Methylcrotonylglycinuria
About the condition	3-MCC deficiency is an organic acid disorder. It is a hereditary disease that is caused by a missing enzyme needed to convert protein into energy.
Inheritance	Autosomal recessive
Year screening started in WA	2005
Incidence in Australia	Currently unknown
Enzyme defect	Deficiency of the enzyme 3-methylcrotonyl-CoA carboxylase May be seen as part of multiple carboxylase deficiency
Symptoms if untreated	Hypoglycaemia Episodic metabolic acidosis Significant clinical heterogeneity
Metabolites on bloodspot screening	Increased hydroxyisovalerylcarnitine (C5OH).
Diagnostic tests	Plasma acylcarnitine profile Urine organic acids MCCC1 and MCCC2 gene analysis
Treatment	Low-protein diet Carnitine supplementation IV glucose and bicarbonate during crisis episodes
Screening issues	Some children may be asymptomatic Maternal 3-MCC deficiency may be detected incidentally