OBJECTIVETo analyze the phenotype and genotype of CMTX1 patients with episodic transient reversible white matter involvement, and delineate the features of brain MRI in the episode and the possible mechanisms.

METHODThree Chinese probands and their family members were sequenced in the coding regions of GJB1. With the other 16 reported CMTX1 patients with episodic transient reversible white matter involvement, the clinical feature of the episodic central nervous system symptoms and the genotypes were reviewed.

RESULTMissense mutations in GJB1 were identified in all 3 probands. In 19 patients with transient reversible white matter involvement, the episodes were manifested as weakness of the limbs, dysarthria, and dysphagia, without disturbance of consciousness or seizures. The episodes lasted for 13 hours (10 min-72 hours) with complete remission in all patients; There were multiple episodes in 9 patients. During the episode, brain MRI showed symmetrical high signals in T2 weighted, Flair and DWI images in periventricular white matter, with predominance in posterior region including splenium of corpus callosum. These changes in imaging were most prominent during or within 1 week after the clinical episode.Significant improvements occurred within 1 month, with complete remission within 4-6 months.No specific locations of mutant amino acids in GJB1 protein were found in these patients with episodic transient reversible white matter involvement.

CONCLUSIONEpisodic transient reversible white matter involvement may present in a small number of patients with CMTX1. Transient edema of oligodendrocytes due to the dysfunction of gap junction may be involved in the pathogenesis. There is no correlation between the location of the mutant amino acids in GJB1 and the occurrence of the episodes.