WHAT IS MYELIN?
Myelin - The white matter surrounding our nerves, made up of phospholipids-proteins of the cell membranes of Schwann cells (parasympathetic nervous system) and oligodendrocytes (central nervous system) and forms the insulating coating around the nerves. It acts as an electrical insulator and increases the speed of impulse transmissions.

In simple terms: You can think of the myelin sheath as the insulating cover to an electrical wire, when its frayed or cut in places; the electrical current of the wire loses its ability to conduct itself to the intended appliance or even just shorts out. The same applies in our bodies, if the nerve is not insulated, the message our brain sends to the intended appliance (muscle) loses its path along the way and we lose mobility and capability.

DEMYELINATING DISEASES
There are two main forms of demyelinating diseases, acquired, such as Multiple Sclerosis, and hereditary, such as the many leukodystrophies.

Multiple sclerosis: A disorder of the central nervous system of unknown cause in which the body's immune system attacks myelin in the brain and spinal cord. Whether the disease manifests in repeated episodes of inflammation or as a chronic condition, it results in multiple scars, or scleroses, on the myelin sheath, leading to impairment or loss of nerve function. There are four forms commonly recognised: Benign, Relapsing/Remitting, Primary Progressive and Secondary Progressive Multiple Sclerosis.

Leukodystrophy: Leuko - Greek word meaning 'white. Dys - Greek word meaning 'ill'. Trophy - Greek word meaning 'growth'. So, quite literally, leukodystrophies are a group of genetic disorders characterized by the imperfect development or maintenance of myelin (white matter). Currently, all Leukodystrophies are incurable and dramatically affect the lifespan of one affected.

Diseases in this class include
18q Syndrome With Deficiency of Myelin Basic Protein
Acute Disseminated Encephalomyeolitis (ADEM)
Acute disseminated Leukoencephalitis
Acute Hemorrhagic Leukoencephalopathy
Adrenoleukodystrophy (ALD)
Adrenomyeloneuropathy (AMN)
Aicardi-Goutieres Syndrome
Alexander Disease
Autosomal Dominant Diffure Leukoencephalopathy with Neuroaxonal Spheroids
Autosomal Dominant Late-onset Leukoencephalopathy
Childhood Ataxia with Diffuse CNS Hypomyelination (CACH or Vanishing White Matter Disease)
Canavan disease, Cerebral Autosomal Dominant Arteropathy with Subcortal Infarcts and Leukoencephalopathy (CADISIL), Cerebrotendinous Xanthomatosis (CTX)
Craniometaphysical Dysplasia with Leukoencephalopathy
Extensive Cerebral White Matter Abnormality Without Clinical Symptoms
Familial Leukodystrophy With Adult Onset Dementia and Abnormal Glycolipid Storage
Globoid Cell Leukodystrophy also known as Krabbe disease
Hereditary Adult Onset Leukodystrophy Simulating Chronic Progressive Multiple Sclerosis
Lipomembranous Osteodysplasia With Leukodystrophy (Nasu Disease)
Metachromatic Leukodystrophy (MLD)
Megalencephalic Leukodystrophy with Subcortal Cysts (MLC)
Neonatal ALD
Neuroaxonal Leukoencephalopathy With Axonal Spheroids
Oculodetatoldigital Dysplasia With Cerebral White Matter Abnormalities
Orthochormatic Leukodystrophy With Pigmented Glia
Ovarioleukodystrophy Syndrome
Pelizaeus-Merzbacher Disease (PMD)
Phenylketonuria (PKU), Refsum disease
Sjogren-Larssen Syndrome
Sudanophilic Leukodystrophy
Van der Knaap Syndrome (Vacuolating Leukodystrophy With Subcortal Cysts or MLC)
Vanishing White Matter Disease (Childhood Ataxia With Diffuse CNS Hypomyelination or CACH)
X-Linked ALD
Zellweger Spectrum and Zellweger Syndrome.