GJB1

(redirected from CMTX1)

GJB1

A gene on chromosome Xq13.1 that encodes a beta chain of the gap junction protein family or connexions.

Molecular pathology
GJB1 mutations cause X-linked Charcot-Marie-Tooth disease, an inherited peripheral neuropathy.
References in periodicals archive ?
X-linked hereditary motor sensory neuropathy type 1 (CMTX1) in a three-generation Gelao Chinese family.
CNS involvement in CMTX1 caused by a novel connexin 32 mutation: A 6-year follow-up in neuroimaging and nerve conduction.
Clinical examination, nerve conduction studies, and molecular and bioinformatics analyses were performed to identify patients with CMTX1. Results: Nine GJB1 mutations (c.283G>A, c.77C>T, c.643C>T, c.515C>T, c.191G>A, c.610C>T, c.490C>T, c.491G>A, and c.44G>A) were discovered in nine patients.
On the other hand, genetic testing provides an exact diagnosis of a specific subtype of CMT, including CMT1A, CMT1B, CMT1C, CMT1D, CMT1F, CMTX1, CMT2A1, CMT2A2, CMT2B, and CMT2O.
GJB1 was included to identify patients with CMTX1. Genomic DNA was extracted from peripheral leukocytes of fresh blood samples of patients, and target genes were captured by the GenCap target region probe (MyGenostics, MD, USA) and amplified by polymerase chain reaction (PCR).
In addition, patient #4 (female) with c.515C>T mutation (het) was reported to have X-linked recessive CMT.[sup][18] Although some cases have been reported to have “recessive” CMTX1, some obligate carriers among these have electrophysiological evidence of peripheral neuropathy.[sup][13]
A study indicates that in CMTX1, demyelination occurs initially, followed by chronic remyelination; when demyelination has advanced to a certain extent, axonal loss begins.[sup][4] There is a gender-based predisposition, and males are usually more affected than females in CMTX1.
CNS involvement has been reported in CMTX1 patients.[sup][13] Apparently many, but not all, patients with CMT1X show abnormalities of evoked potentials.[sup][21] CX32 is expressed by Schwann cells in the PNS and oligodendrocytes in CNS.
CMTX1 (MIM 302800) is an X-linked dominant trait caused by mutations in the GJB1 [gap junction protein, beta 1, 32kDa (connexin 32, Charcot-Marie-Tooth neuropathy, X-linked)] gene (3).
1G) are previously unreported novel mutations that further demonstrate the allelic heterogeneity of CMTX1.