Leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation: high outcome variation between two siblings.

Leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation is a rare disorder caused by mutations in the gene encoding a mitochondrial aspartyl-tRNA synthetase, DARS2. Clinical features include childhood or adolescent onset, slowly progressive ataxia, spasticity, and dorsal column dysfunction with or without mild cognitive decline. Magnetic resonance (MR) images show a characteristic leukoencephalopathy with multiple long tract involvement. MR spectroscopy shows elevated levels of lactate. We present strikingly different clinical courses and discrepant MR images findings for a pair of brothers. It cannot be excluded that in the cases presented, the different clinical outcome is related to a varicella infection in infancy in the younger brother.