Congenital hypomyelination due to myelin protein zero Q215X mutation.

Congenital hypomyelination (CH) is a hereditary demyelinating peripheral neuropathy characterized by early infancy onset, distal muscle weakness, hypotonia, areflexia, and severe slowing of nerve conduction velocities. In the present report, the clinical, morphological, and immunohistochemical features of a CH case and the identification of a mutation in the gene (MPZ) for protein zero (P0) associated with this phenotype are described. This "de novo" mutation in a patient presenting with clinical features quite distinct from those of the more frequent Charcot-Marie-Tooth type 1B disease (CMT1B) or Dejerine-Sottas syndrome (DSS) confirms that CH is allelic with other disorders characterized by a less severe phenotype and a different clinical and neuropathological profile.