Ultra–sensitive droplet digital PCR for detecting a low–prevalence somatic GNAQ mutation in Sturge–Weber syndrome

Citations Over TimeTop 10% of 2016 papers

Abstract

Droplet digital PCR (ddPCR), a method for measuring target nucleic acid sequence quantity, is useful for determining somatic mutation rates using TaqMan probes. In this study, the detection limit of copy numbers of test DNA by ddPCR was determined based on Poisson distribution. Peptide nucleic acid (PNA), which strongly hybridises to target lesions, can inhibit target amplification by PCR. Therefore, by combination of PCR with PNA and ddPCR (PNA-ddPCR), the detection limit could be lowered. We reanalysed a somatic GNAQ mutation (c.548G > A) in patients with Sturge-Weber syndrome (SWS) using ddPCR and PNA-ddPCR. Importantly, among three patients previously found to be mutation negative by next-generation sequencing, two patients had the GNAQ mutation with a mutant allele frequency of less than 1%. Furthermore, we were able to find the same mutation in blood leukocyte or saliva DNA derived from four out of 40 SWS patients. Vascular anomalies and blood leukocytes originate from endothelial cells and haemangioblasts, respectively, which are both of mesodermal origin. Therefore, blood leukocytes may harbour the GNAQ mutation, depending on the time when the somatic mutation is acquired. These data suggest the possibility of diagnosis using blood DNA in some patients with SWS.

Related Papers

• → The somatic GNAQ mutation c.548G>A (p.R183Q) is consistently found in Sturge–Weber syndrome(2014)140 cited
• → Association of SomaticGNAQMutation With Capillary Malformations in a Case of Choroidal Hemangioma(2018)56 cited
• → GNAQ Mutation in the Venous Vascular Malformation and Underlying Brain Tissue in Sturge–Weber Syndrome(2017)49 cited
• → Identification of a Mosaic Activating Mutation in GNA11 in Atypical Sturge-Weber Syndrome(2020)48 cited
• → Hypothalamic Glioma in a Patient With Sturge-Weber Syndrome(2015)5 cited