Biotinase is an important mitochondrial enzyme involved in the biotin metabolic cycle. A patient with an inherited deficiency may be unable to release dietary protein-bound biotin or to recycle endogenous biotin.
Inheritance: autosomal recessive (may have affected siblings)
Onset: from shortly after birth to 10 years of age, with most during infancy
Metabolic findings:
(1) metabolic acidosis (ketolactic)
(2) organic aciduria
(3) mild hyperammonemia
Neurologic findings:
(1) seizures
(2) lethargy
(3) hearing loss
(4) hypotonia
(5) ataxia
(6) coma
(7) a speech disorder
(8) developmental delay
Respiratory changes:
(1) tachypnea
(2) apnea
(3) other breathing problems
Skin findings:
(1) alopecia
(2) skin rash (seborrheic dermatitis)
Ocular findings:
(1) conjunctivitis
(2) visual loss
(3) optic atrophy
Gastrointestinal findings:
(1) vomiting
(2) diarrhea
(3) feeding difficulties
Other findings:
(1) hepatomegaly
(2) splenomegaly
(3) recurrent fungal infections
Confirmatory features:
(1) low serum biotinidase activity
(2) clinical improvement with biotin replacement therapy
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