Leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation (LBSL) is a result of a DARS2 gene mutation and is characterized by slowly progressive cerebellar ataxia and spasticity with dorsal column dysfunction (decreased position and vibration sense).

The neurologic dysfunction involves the legs more than the arms. The tendon reflexes are retained. Deterioration of motor skills usually starts in childhood or adolescence, but occasionally not until adulthood. Dysarthria develops over time.

Occasional findings include epilepsy; learning problems; cognitive decline; and reduced consciousness, neurologic deterioration, and fever following minor head trauma. Many affected individuals become wheelchair dependent in their teens or twenties.

LBSL is inherited in an autosomal recessive manner. At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk family members and prenatal testing for pregnancies at increased risk are possible if the disease-causing mutations have been identified in the family.