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 II, type III

Current page: Metachromatic leukodystrophy - type I 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 in 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.

Hypotonia

Progressive loss of physical and intellectual functions in all forms of the disease. Initial symptoms (usually noted between 6 months and 2 years of age) are typically the development of walking difficulties in those who have learned to walk, and speech deterioration in those who have begun to talk. The later the age of onset, the slower the rate of progression.

Psychomotor retardation

Progressive hypotonia and motor weakness

Knee hyperextension with genu recurvatum

Initial decreased or absent deep tendon reflexes

Dysarthria and aphasia with speech deterioration leading to loss of speech

Mental regression

Myoclonic seizures

Peripheral neuropathy

Ataxia

Irritability

Muscle wasting

Truncal titubation

Urinary incontinence with urinary tract infections

Nystagmus

Grayish discoloration of the macula

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.