Quantifying Disease Progression in Leukoencephalopathy With Brainstem and Spinal Cord Involvement and Lactate Elevation (LBSL)

Leukoencephalopathy with brain stem involvement and lactate elevation (LBSL) is a genetic disorder caused by biallelic mutations in the DARS2 gene that encodes mitochondrial aspartyl tRNA synthase.(1, 2) It is characterized by typical abnormalities on MRI of the brain and spinal cord.(3) Clinically, the disorder is heterogeneous and can present in the neonatal period, later in childhood or even in adults.(3) In general it can be stated that the earlier presentations are characterized by rapid progression leading to severe disability and death. Presentation at a later age is typically characterized by a more benign disease course, although considerable disability is common. Clinically, the disease presents as a slowly progressive myelopathy with mainly involvement of the corticospinal tracts and the dorsal columns. Although the natural history has been studied in large cohorts, the rate of progression has not been systematically studied with clinimetric outcome scales or potential surrogate outcomes for spinal cord disease.