Metabolic defect: arylsulfatase A (ASA) deficiency Other sphingolipid degradation diseases: acid sphingomyelinase deficiency | Fabry | Farber | Gaucher: type I, type II, type III | GM1 gangliosidosis: type I, type II, type III | Tay-Sachs: type I, type II, type III | Sandhoff: type I | Krabbé | metachromatic leukodystrophy: type I, type II

Current page: Metachromatic Leukodystrophy - type III Select Another Disease Select disease Acid sphingomyel. def. Aspartylglycosaminuria Cystinosis Fabry disease Farber disease Fucosidosis type I Fucosidosis type II Galactosialidosis Gaucher type I Gaucher type II Gaucher type III GM1 gangliosidosis I GM1 gangliosidosis II GM1 gangliosidosis III Infantile sialic acid Krabbé disease Mannosidosis Metachr. leukodys. I Metachr. leukodys. II Metachr. leukodys. III MPS I MPS II Hunter MPS III Sanfilippo MPS IV Morquio MPS VI Maroteaux-Lamy MPS VII Sly Mucolipidosis II Mucolipidosis III Mucolipidosis IV Neuro ceroid lipof I Neuro ceroid lipof II Neuro ceroid lipof III Neuro ceroid lipof IV Pompe disease Pycnodysostosis Salla disease Sandhoff type I Sialidosis type I Sialidosis type II Tay-Sachs type I Tay-Sachs type II Tay-Sachs type III

One of a group of genetic disorders called the leukodystrophies that affect the growth of the myelin sheath, the fatty covering on nerve fibers in the brain that acts as an insulator. MLD is the result of a failure in the breakdown of sulfatides in the course of normal myelin maintenance and replacement. This is usually the result of a severe deficiency in arylsulfatase A, the first enzyme in the sulfatide degradative pathway.

Dystonia		Dystonia		Dystonia		Strabismus

Progressive loss of physical and intellectual functions in all forms of the disease. Normal development up to puberty, then cognitive and behavioral abnormalities. Initial symptoms often relate to a deterioration of intellectual performance and/or behavioral changes, often diagnosed as a variety of psychiatric conditions. The later the age of onset, the slower the rate of progression.

Diagnosis: Enzyme (ASA) deficiency, Saposin B deficiency. Urinary sulfatides. Symptoms and laboratory tests, including brain CT and MRI, nerve conduction velocity

Progressive clumsiness and slowing

Increasing muscle tone leading to spasticity of limbs

Increased deep tendon reflexes

Dystonic movements and pareses

Generalized seizures

Peripheral neuropathy

Cognitive/behavioral problems:

Personality changes

Anxiety, apathy, bewilderment, emotionally lability

Psychosis

Decreased mental alertness

Defective visual-spatial discrimination

Disorganized thinking

Horizontal nystagmus

Optic atrophy leading to blindness

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1. National Institute of Neurological Disorders and Stroke www.ninds.nih.gov/health_and_medical/disorders/meta_leu_doc.htm. Accessed July 2004.

2. Nyhan WL, Ozand PT. Atlas of Metabolic Diseases. London: Chapman & Hall Medical, 1998; 608-613.

3. Meikle PJ, Hopwood JJ, Clague AE, Carey WF. Prevalence of Lysosomal Storage Disorders. JAMA. 1999; 281: 249-254.

4. National Center for Biotechnology Information; OMIM(TM), Online Mendelian Inheritance in Man. www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=250100 Accessed July 2004.

5. Lyon G, Adams RD, Kolodny EH. Neurology of Hereditary Metabolic Diseases of Children. McGraw-Hill, 2nd edition. 1996; 244-245