Biotinidase is the preferred test for diagnosing biotinidase deficiency and can be used as a follow up test for certain organic acidurias.
Biotinidase deficiency is an autosomal recessive metabolic disease in which biotin is not released from proteins during digestion or normal cellular protein turnover.
Symptoms of the disease are caused by the inability to re-use biotin.
Age of onset and clinical phenotype vary among individuals depending on the amount of residual biotinidase activity. Profound biotinidase deficiency occurs in approximately 1 in 137,000 live births and partial biotinidase deficiency occurs in approximately 1 in 110,000 live births, resulting in a combined incidence of about 1 in 61,000. The carrier frequency for biotinidase deficiency within the general population is about 1 in 120.
Untreated profound biotinidase deficiency typically manifests within the first decade of life as seizures, ataxia, developmental delay, hypotonia, sensorineural hearing loss, vision problems, skin rash, and/or alopecia. Partial biotinidase deficiency is associated with a milder clinical presentation, which may include cutaneous symptoms without neurologic involvement. Certain organic acidurias, such as holocarboxylase synthase deficiency, isolated carboxylase synthase deficiency and 3-methylcrotonylglycinuria, present similarly to biotinidase deficiency. Serum biotinidase levels can help rule out these disorders.
Treatment with biotin is successful in preventing the clinical features associated with biotinidase deficiency. In symptomatic patients, treatment will reverse many of the clinical features except developmental delay and vision and hearing complications
0 – 6 month: 2.1 – 8.0 nmol/mL/min
6 month – 115 years: 2.4 – 8.2 nmol/mL/min
Blood specimen in a Lithium Heparin (green top) Tube or paediatric equivalent.
Paediatric Metabolic Centre