Biotinidase deficiency

Alternative names	Late-Onset Biotin-Responsive Multiple Carboxylase Deficiency
About the condition	Biotinidase deficiency is an inherited condition in which the body is unable to reuse and recycle biotin. Free biotin is used to metabolise fats, proteins, and carbohydrates effectively.
Inheritance	Autosomal recessive
Year screening started in WA	2026
Incidence in Australia	Low; exact figures currently unknown
Defect	The enzyme biotinidase is required to release protein-bound biotin in foods and recycle biotin used in metabolism. Biotin (vitamin B7) is required to activate several enzymes involved in carbohydrate, fat and protein metabolism: Propionyl-CoA carboxylase, acetoacetyl-CoA carboxylase, pyruvate carboxylase, and 3-methylcrotonyl-CoA carboxylase.
Symptoms if untreated	Seizures Lethargy, poor feeding Hypotonia Skin rash and hair loss Developmental delays Neurosensory hearing loss Ataxia Optic atrophy Hyperventilation
Determinantson bloodspot screening	Deficient blood spot biotinidase enzyme activity
Diagnostic tests	Plasma acylcarnitine profile Urine organic acids BTN gene analysis
Treatment	Dietary biotin supplementation
Screening issues	Post-transfusion samples may provide a false normal result. A pre-transfusion sample is required.