[A girl presenting clinical course and neuroimagings on MRI compatible with Pelizaeus-Merzbacher disease].

A 5-year-old girl who showed congenital nystagmus and mental and motor developmental delay, is described. Auditory brainstem responses (ABR) revealed wave I at normal latency, but all of the following waves were absent. In T2-weighted images, magnetic resonance imaging (MRI) demonstrated diffuse high intensity area of cerebral white matter, suggesting extensive dysmyelination or demyelination. She has not shown any deterioration through her clinical course. Subsequent MRI examinations did not demonstrate a progressive disorder. These findings suggest the possibility of Pelizaeus-Merzbacher (P-M) disease in this patient, which is a rare form of sudanophilic leukodystrophy, transmitted by an X-linked recessive mutant gene. It is reported that the proteolipid protein, one of the major proteins of myelin, was absent in classical type P-M disease, resulting in dysmyelination. Because chromosomal study showed the normal female karyotype and no family history of a similar disease was found in this case, it might be different from classical P-M disease. Since P-M disease may be heterogeneous, more detailed chromosomal analysis in each case of congenital hypomyelination will give a clue to clarify the pathogenesis of P-M disease and other disorders showing failure in myelination.