The term Leukodystrophy refers to a group of progressive hereditary disorders that affect the protective coating around the transmitting arm of the neuron which is known as the Axon. This whitish, jelly like coating is known as Myelin and one of its major functions is to insulate the axon and greatly increase the speed of transmission to the receiving arm of the neuron which is known as a Dendrite. It does this by preventing the axon from absorbing the electrical charge and preventing external leakage when it wishes to send or “fire” a message to another neuron .
The purpose of this firing process is to send some information to either our Sensory, interneurons or Motor neurons which then allow us to achieve some function of feeling or voluntary action. This constant and complex action occurs in our Nervous System which is made up of two major elements; the central nervous system (CNS) and the peripheral nervous system (PNS).
The Central Nervous System consists of our brain and spinal cord and the Peripheral Nervous System is the carrier of messages to and from the central nervous system. Very simplistically the PNS has two other sub systems which are known as the Somatic and Autonomic nervous systems. The Somatic system carries sensory information and sends motor messages to muscles whilst the Autonomic handles such involuntary functions as heart beat and breathing. The autonomic system also controls the Sympathetic and Parasympathetic nervous systems. The former is involved with such matters as our fight flight response whilst the parasympathetic’s function is to get us back on an even keel after such events.
This brief overview hopefully will help explain why such a wide range of unpleasant events occur to those affected by Leukodystrophy. This hereditary disorder happens due to a genetic mutation which causes imperfect growth or maintenance of the myelin. Nearly all Leukodystrophies are monogenitic and the defective gene causes a protein or enzyme not to properly function. This creates the problem where the myelin fails to develop properly, breaks down or is destroyed. A Protein is arguably the most important molecule in our body and they are the basis for human tissue. An Enzyme is a protein that is a biological catalyst which drives a desired reaction. Any if of these are missing or defective it is often with a disastrous outcome.
Other terms that maybe helpful to understand are those that refer to the state of the myelin and its abnormality. Demyelination refers to the loss of the myelin sheath whilst dysmyelination is about the defective structure and it does not produce lesions. Hypomyelination is about abnormally reduced amounts on myelin.
To parse the term Leukodystrophy, the Greek word for white is Leuko and Dystrophy means lack of nutrition. In other words the brains white matter , our myelin is not receiving the correct nutrition to function as it should.
There are no known cures for any of the Leukodystrophies at the moment however there is some very exciting research work currently being done with some of them.