Scalabrino et al. described how in rat spinal cord, vitamin B12 deficiency increases the synthesis of myelinotoxic cytokines (e.g., tumor necrosis factor) and a myelinotoxic growth factor (nerve growth factor), but decreases synthesis of a myelinotrophic cytokine (interleukin-6) and a myelinotrophic growth factor (epidermal growth factor). The gene discussed is NGF; the disease is vitamin B12 deficiency.