[Optic neuropathy in biotinidase deficiency]. / Neuropatía óptica por déficit de biotinidasa.

CLINICAL CASE: We report a case of a 12 year old male with vision loss (0.1 in both eyes). He also had sensorineural hearing loss (cochlear implant), asthma, dermatitis and alopecia. He was diagnosed with retrobulbar optic neuropathy, and was started on a treatment of intravenous corticosteroids, showing no improvement. A screening for congenital metabolopathies revealed a biotinidase deficiency, and treatment with biotin achieved a rapid clinical improvement. DISCUSSION: When faced with an optic neuropathy in a child, we must always look for a biotinidase deficiency, because biotin therapy is the only treatment that achieves a clinical improvement.