GNAQ mutation R183Q as a potential cause of familial Sturge-Weber syndrome: A case report.

Sturge-Weber syndrome (SWS) is a rare neurocutaneous disorder whose etiology remains unclear. To investigate the genetic contribution underlying this disease, the genetic variants of a 4-generation family with a history of SWS was analyzed in the present study. SWS was diagnosed in 3 of the family members (II-1, III-11 and IV-6). Sanger sequencing was performed to identify mutations in G protein subunit αq (GNAQ) and RAS p21 protein activator 1 exons in the 3 patients with SWS and other unaffected family members. Notably, a non-synonymous single-nucleotide variant at codon 183 on exon 4 of the GNAQ gene was identified as the only pathogenic site. This variant generated a substitution of arginine (R) with glutamine and resulted in a change of function of the encoded protein. Evolutionary conservation analysis revealed that the mutated residue 183 (R) of GNAQ is highly conserved across several vertebrate species. Furthermore, an immunofluorescence staining assay demonstrated that the substitution of arginine with glutamine resulted in a change in the sub-cellular localization of the GNAQ recombinant protein in vitro. These findings may aid in the development of novel diagnostic markers and/or therapeutic targets for the treatment of patients with familial SWS.