Two Cases of Multiple Sclerosis in a Family With X-Linked Charcot-Marie-Tooth Disease

The aim of this study was to present a case report of the first familial case of multiple sclerosis (MS) in an X-linked Charcot-Marie-Tooth family with a novel variant in GJB1.

Clinical, neurophysiologic, neuroimaging, and genetic assessments were performed on 9 affected members of a large X-linked Charcot-Marie-Tooth (CMTX) family, including 2 who also developed MS. The 2 family members with CMTX and MS were screened for pathogenic variants in 245 genes associated with MS. We tested 150 independent patients with MS, 48 familial and 102 sporadic for rare pathogenic variants in GJB1.

A novel missense pathogenic variant (c.502T > G, p.Cys168Gly) in GJB1 was detected in a large CMTX family. Two 5th-degree relatives developed typical MS in addition to CMTX. No additional pathogenic genetic variants were identified in 245 MS-associated genes in 2 MS patients with exome sequencing data. Furthermore, GJB1 pathogenic variants were not found in a cohort of 48 patients with familial and 102 with sporadic MS.

This is a novel report of a familial case of MS related to the novel variant in GJB1. Although our report adds additional evidence for the increased risk of MS in carriers of pathogenic variants in GJB1, we demonstrate that genetic variation in GJB1 is not a common risk factor, neither in familial nor sporadic MS.