[Clinical and genetic analysis of a Chinese pedigree affected with Charcot-Marie-Tooth disease presenting as childhood-onset encephalopathy].

OBJECTIVE

To explore the clinical phenotypes and genetic characteristics of a Chinese pedigree affected with X-linked Charcot-Marie-Tooth disease (CMTX) with childhood-onset episodic encephalopathy as the initial manifestation.

METHODS

Clinical data and auxiliary examination results of a pedigree with "limb weakness, dysarthria and dysphonia" presented at the Affiliated Hospital of Guangdong Medical University between April 2023 and December 2024 were retrospectively analyzed. The proband and other pedigree members underwent whole exome sequencing. Candidate variants were subsequently validated within the pedigree by Sanger sequencing. In addition, literature search and summary analysis were carried out using keywords including "X-linked Charcot-Marie-Tooth disease type 1," "children," and "GJB1 gene" in the China National Knowledge Infrastructure, WanFang Data Knowledge Service Platform, and PubMed databases. This study was approved by the Medical Ethics Committee of the Affiliated Hospital of Guangdong Medical University (Ethics No.: YJYS2022352).

RESULTS

The pedigree has comprised five affected individuals from three generations. The probands were monozygotic male twins with the onset age of 10 and 11 years, respectively, without preceding infection. Both child had presented with limb weakness, dysarthria, and dysphonia as initial symptoms, which were improved with treatment. Brain MRI revealed bilateral frontoparietal white matter lesions. Electromyography demonstrated peripheral neuropathy in the four limbs. Whole exome sequencing identified a c.224G>A (p.Arg75Gln) missense variant in the GJB1 gene, which was inherited from the mother. The variant was classified as pathogenic based on the guidelines from American College of Medical Genetics and Genomics (ACMG) (PS3+PS4+PM2_Supporting+PM5+PP3), confirming the diagnosis of CMTX1. No symptom has occurred during the follow-up, and repeat brain MRI one year post-onset showed complete resolution of the abnormalities. Literature review has identified 18 male pediatric CMTX1 cases presenting with encephalopathy as the initial manifestation. Episodic limb weakness, dysarthria, and facial palsy were the main clinical manifestations. MRI predominantly showed transient hyperintense signals in the periventricular deep white matter, centrum semiovale, and splenium of corpus callosum, which resolved spontaneously within weeks to months.

CONCLUSION

For male pediatric patients presenting with episodic encephalopathy, peripheral neuropathy, and transient white matter abnormalities on brain MRI, CMTX1 should be suspected. Early implementation of neurophysiological studies and GJB1 gene testing is crucial for timely diagnosis, precise management, and accurate genetic counseling.