This disease is characterized by progressive cerebellar ataxia with pyramidal and spinal cord dysfunction, associated with distinctive MRI anomalies and increased lactate in the abnormal white matter. The disease is Monarch Disease Ontology identifier MONDO_0012622 (leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome). Also known as: LBSL, Leukoencephalopathy with Brain Stem and Spinal Cord Involvement and Lactate Elevation, leukoencephalopathy with brain stem and spinal cord involvement-lactate elevation syndrome.