Biotin-responsive encephalopathy with myoclonus, ataxia, and seizures.
Prominent neurological abnormalities, including myoclonus, seizures, ataxia, and hearing loss, have been noted in juvenile-onset biotin-responsive MCD. The underlying defect in many of these patients, who generally present in the first year of life, appears to be a deficiency of biotinidase. We have presented a young woman with adult-onset myoclonus, ataxia, hearing loss, seizures, hemianopia, and hemiparesis who responded to pharmacologic dosages of biotin. Although she displayed many of the clinical and biochemical features of juvenile-onset MCD, she did not have a biotinidase deficiency, and the underlying defect remains to be determined. Because of her response to biotin, we have advocated that other patients with unexplained myoclonus syndromes be evaluated for biotin-dependent carboxylase deficiencies and undergo a therapeutic trial with biotin.
D000328:Adult; D000581:Amidohydrolases / Q000172:deficiency; D001259:Ataxia / Q000150:complications*; D001710:Biotin / Q000097:blood / Q000627:therapeutic use*; D043523:Biotinidase; D001928:Brain Diseases, Metabolic / Q000150:complications / Q000188:drug therapy*; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D034381:Hearing Loss / Q000150:complications; D006801:Humans; D009207:Myoclonus / Q000150:complications*; D011766:Pyruvate Carboxylase / Q000097:blood; D012640:Seizures / Q000150:complications*
D001710:Biotin; D000581:Amidohydrolases; D043523:Biotinidase; D011766:Pyruvate Carboxylase