Biotinidase deficiency: accumulation of lactate in the brain and response to physiologic doses of biotin.

Biotinidase deficiency is the most common cause of late onset, biotin-responsive multiple carboxylase deficiency (MCD). We studied the two oldest known boys with this disorder who had high CSF content of lactate that could have contributed to the clinical disorder. The symptoms of these patients implied that near physiologic, rather than pharmacologic, doses of biotin may be sufficient for treatment.