Supplementary Material for: Vocal cord paresis and neuropathic pain in infantile LBSL. A case report

Introduction
Mutations in the Aspartyl-tRNA synthetase 2 (DARS2) gene cause the rare disease leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL). Mitochondrial dysfunction leads to characteristic abnormalities in cerebral white matter, brainstem and spinal cord. Symptoms usually present in childhood and progress slowly, but a more severe infantile form exists, often with rapid deterioration.
Case Presentation
We present a young Norwegian boy with hypotonia, areflexia, obesity and vocal cord paresis, as well as extreme pain and swift disease progression. He had two DARS2 variants, which through functional analyses were confirmed as causative. He was treated with high doses of ketamine that allowed for effective pain relief and lenient palliative care.
Conclusion
This patient had an aggressive form of LBSL, and we propose a genotype-phenotype relationship as well as suggestions for suitable palliative care.