Exome sequencing identifies GNB4 mutations as a cause of dominant intermediate Charcot-Marie-Tooth disease.

ABSTRACT: Charcot-Marie-Tooth disease (CMT) is a heterogeneous group of inherited neuropathies. Mutations in approximately 45 genes have been identified as being associated with CMT. Nevertheless, the genetic etiologies of at least 30% of CMTs have yet to be elucidated. Using a genome-wide linkage study, we previously mapped a dominant intermediate CMT to chromosomal region 3q28-q29. Subsequent exome sequencing of two affected first cousins revealed heterozygous mutation c.158G>A (p.Gly53Asp) in GNB4, encoding guanine-nucleotide-binding protein subunit beta-4 (G?4), to cosegregate with the CMT phenotype in the family. Further analysis of GNB4 in an additional 88 unrelated CMT individuals uncovered another de novo mutation, c.265A>G (p.Lys89Glu), in this gene in one individual. Immunohistochemistry studies revealed that G?4 was abundant in the axons and Schwann cells of peripheral nerves and that expression of G?4 was significantly reduced in the sural nerve of the two individuals carrying the c.158G>A (p.Gly53Asp) mutation. In vitro studies demonstrated that both the p.Gly53Asp and p.Lys89Glu altered proteins impaired bradykinin-induced G-protein-coupled-receptor (GPCR) signaling, which was facilitated by the wild-type G?4. This study identifies GNB4 mutations as a cause of CMT and highlights the importance of G?4-related GPCR signaling in peripheral-nerve function in humans.

SUBMITTER: Soong BW 

PROVIDER: S-EPMC3591844 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature