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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