Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (commonly referred to as LBSL) is a progressive disorder that affects the brain and spinal cord.

Leukoencephalopathy refers to abnormalities in the white matter of the brain, which is tissue containing nerve cell fibers (axons) that transmit nerve impulses.

LBSL is a rare genetic disorder that affects the brain and spinal cord. The exact number of people with this condition is unknown, and many may go undiagnosed, but based on reported cases, there are approximately 100 known patients worldwide.

Most affected individuals begin to develop movement problems during childhood or adolescence. However, in some individuals, these problems do not develop until adulthood. Symptoms include:

  • Abnormal muscle stiffness (spasticity) and difficulty with coordinating movements (ataxia).
  • Loss of the ability to sense the position of their limbs or vibrations with their limbs, and as a result most affected individuals eventually require wheelchair assistance, sometimes as early as their teens, although the age varies.
  • Some affected individuals develop recurrent seizures (epilepsy), speech difficulties (dysarthria), learning problems, or mild deterioration of mental functioning.
  • Some people with this disorder are particularly vulnerable to severe complications following minor head trauma, which may trigger a loss of consciousness, other reversible neurological problems, or fever.


LBSL is diagnosed on the basis of the clinical symptoms in combination with specific MRI and magnetic resonance spectroscopy (MRS) findings. Genetic testing is required to identify the DARS2 genetic mutation and confirm diagnosis. LBSL is inherited in an autosomal recessive manner, meaning most patients have inherited two copies of the mutated gene – one from each parent. Parents who are both carries of the DARS2 mutation have a 25% chance of having a child with LBSL.


There is currently no curative treatment for LBSL. Treatment for LBSL is directed at the symptoms as they arise and includes supportive therapies like physical therapy and rehabilitation to improve motor function, speech therapy and drugs to prevent seizures.  Research to develop new drug therapies are ongoing at the Moser Center for Leukodystrophies