This disorder is usually classified into late infantile, juvenile and adult forms. In late infantile MLD the first signs are loss of acquired skills including walking. Later, patients become ataxic and speech becomes impaired. The disorder progresses until all voluntary actions are lost, including speech and swallowing. Death usually results from bronchopneumonia, sometimes several years after onset. In the juvenile form the course is similar, but the age of onset is 3 to 20 years. The adult form is characterised by initial mental rather than motor abnormalities, including schizophrenia, but neurological signs occur later.
Enzyme Tests: Deficiency of arylsulphatase A is the primary defect.