n :  a familial degenerative disease of the central nervous system that is characterized by slowly progressive demyelination of white matter resulting in mental deterioration and the occurrence of various motor disorders (as ataxia and nystagmus)
 
Pelizaeus, Friedrich (1850-1917), and Merzbacher, Ludwig (b 1875), German neurologists. In 1885 Pelizaeus described a congenital and familial disease that is due to atrophy of the white matter of the brain and whose characteristics include speech disturbances, loss of coordination, and mental retardation. Merzbacher independently described the same disease in 1908.
 
 
 
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