The insulation material that is made from proteins and lipids (fats etc) that is produced in the neuron to coat and protect the transmission arm of the neuron – the axon. This process is called Myelination. Myelin is a spongy substance which is white in appearance and is referred to as “the white matter” of the brain. The major purpose of the myelin is to increase the speed of transmission of an impulse. When this process is disrupted or destroyed by a dysfunctional metabolic process, with a genetic cause it can be classified as a Leukodystrophy.