(HealthDay News) – A somatic single nucleotide mutation causes Sturge-Weber syndrome and port wine stains, according to a study published online May 8 in the New England Journal of Medicine.
Matthew D. Shirley, PhD, from the Johns Hopkins School of Medicine in Baltimore, and colleagues performed whole-genome DNA sequencing on paired samples from visibly affected and normal tissue from three patients with Sturge-Weber syndrome. Additionally, the presence of somatic mutations was tested using amplicon sequencing and SNaPshot assays in 97 samples from 50 people with the syndrome, a port wine stain, or neither (controls). The effect of the mutation on downstream signaling was detected using antibodies and a luciferase reporter assay.
The researchers identified a nonsynonymous single nucleotide variant in GNAQ in affected tissue samples from 23 of 26 participants with Sturge-Weber syndrome and from 12 of 13 with apparently nonsyndromic port wine stains. No controls or patients with an unrelated cerebrovascular malformation had the variant present. In affected tissue, the mutant allele prevalence was 1–18.1%. There was a modest increase in extracellular signal-regulated kinase activity during transgenic expression of mutant Gαq.
“The Sturge-Weber syndrome and port wine stains are caused by a somatic activating mutation in GNAQ,” the authors write.