Adult-Onset Biotinidase Deficiency Induces Acutely Progressing Leukoencephalopathy

Biotinidase is essential for the recycling of biotin, which serves as a coenzyme for 4 biotin-dependent carboxylases involved in fatty acid synthesis, gluconeogenesis, and amino acid catabolism.(1) Biotinidase deficiency (BD) is a rare, autosomal recessively inherited disorder that if untreated can cause neurologic symptoms including seizures, hypotonia, respiratory abnormalities, and vision/hearing loss, especially in countries that do not screen newborns.(2) This condition is readily treatable with the administration of biotin, but delays in diagnosis and initiation of therapy can result in irreversible neurologic defects. Typically, patients with BD are diagnosed as newborns and treated with biotin administration throughout childhood. Although there are several case reports of adult-onset BD, most patients show some initial symptoms by their 20s or 30s.(3,4) Here, we report an autopsy case of a patient who was aged 63 years at the onset of acutely progressing leukoencephalopathy that was subsequently diagnosed as BD.