Disorder: Multiple carboxylase deficiency (MCD)

Alternative names: Holocarboxylase synthetase (HCS) deficiency

• Increased C5OH acylcarnitines

• Deficiency of holocarboxylase synthetase, the enzyme that covalently links biotin to propionyl-CoA carboxylase, pyruvate carboxylase, and 3-methylcrotonyl-CoA carboxylase

• Autosomal recessive

• Currently unknown

• Plasma carnitine
• Plasma acylcarnitine profile
• Plasma amino acids
• Urine organic acids

• Metabolic ketolactic acidosis
• Vomiting, lethargy
• Seizures, hypotonia
• Skin rashes, hair loss
• Hearing loss, optic atrophy
• Recurrent infections
• Mental retardation
• Coma and death possible
• Later-onset forms occur

• Biotin supplementation

• Expanded Newborn Screening using MSMS

• On-line Mendelian Inheritance in Man