Biotinidase deficiency

Biotinidase deficiency is a rare autosomal recessive condition in which the body is unable to break down the conjugated form of the vitamin B7 (biotin), resulting in low levels of available biotin.

Profound deficiency (<10% of normal level) is estimated at ~1:100,000 of newborns. Profound or partial deficiency (<30% of normal level) is estimated at ~1:60,000 newborns.

Symptoms usually present in infancy with 4:

  • lethargy
  • anorexia
  • hypotonia
  • developmental delay
  • alopecia
  • seborrhoeic dermatitis
  • conjunctivitis and mucositis
  • erythematous rash
  • seizures
  • ataxia
  • lactic acidaemia

In the long term if untreated, hearing loss and optic atrophy can also occur 4.

In biotinidase deficiency in children the neuroimaging findings are relatively non-specific 4.

  • diffuse cerebral and white matter atrophy
  • dilation of the ventricles and extra-axial CSF spaces
  • T1:
    • diffuse or patchy signal abnormalities within cerebral and cerebellar white matter
    • sub-cortical cyst formation
  • T2: 
    • the same changes as above
    • signal abnormalities of the spinal cord may also be seen
  • DWI: areas of restricted diffusion within the signal abnormalities
  • MR spectroscopy:
    • sometimes elevated lactate
    • reduced NAA

Improves with supplemental biotin, which helps with diagnosis.

Biotinidase deficiency meets the major criteria for newborn screening in multiple countries.

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rID: 33766
Synonyms or Alternate Spellings:

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