abnormal myelination GO:0042552 MP:0000920 MP:0001894 MP:0010051 MPheno.ontology absence of myelination absent myelination altered myelination any anomaly in the process by which myelin sheaths are formed and maintained around neurons; oligodendrocytes in the brain and spinal cord and Schwann cells in the peripheral nervous system wrap axons with compact layers of their plasma membrane myelination abnormalities myelination defect abnormal nervous system physiology