Endothelial Cells from Capillary Malformations Are Enriched for Somatic GNAQ Mutations

Abstract

Background A somatic mutation in GNAQ (c.548G>A;p.R183Q), encoding Gαq, has been found in syndromic and sporadic capillary malformation tissue. However, the specific cell type(s) containing the mutation is unknown. The purpose of this study was to determine which cell(s) in capillary malformations have the GNAQ mutation. Methods Human capillary malformation tissue was obtained from 13 patients during a clinically-indicated procedure. Droplet digital PCR (ddPCR), capable of detecting mutant allelic frequencies as low as 0.1%, was used to quantify the abundance of GNAQ mutant cells in capillary malformation tissue. Six specimens were fractionated by fluorescence activated cell sorting (FACS) into hematopoietic, endothelial, perivascular, and stromal cells. The frequency of GNAQ mutant cells in these populations was quantified by ddPCR. Results Eight capillary malformations contained GNAQ p.R183Q mutant cells, 2 lesions had novel GNAQ mutations (p.R183L; p.R183G), and 3 capillary malformations did not have a detectable GNAQ p.R183 mutation. Mutant allelic frequencies ranged from 2% to 11%. Following FACS, the GNAQ mutation was found in the endothelial but not the platelet-derived growth factor receptor-β-positive (PDGFRβ) cell population; mutant allelic frequencies were 3% to 43%. Conculsions Endothelial cells in capillary malformations are enriched for GNAQ mutations and are likely responsible for the pathophysiology underlying capillary malformation.

Somatic GNAQ Mutation is Enriched in Brain Endothelial Cells in Sturge–Weber Syndrome

“…Primers and probes were designed to target GNAQ p.R183Q as described previously 10 . Sequences used were: forward primer (5′-CCTGCCTACGCAACAAGAT-3′); reverse primer (5′-GTAAGTCAAAGGGGTATTCGAT-3′); reference probe (5′-TGCTTAGAGTTCGAGTCCCCACC-3′); mutant probe (5′-TGCTTAGAGTTCAAGTCCCCACC-3′).…”

“…The p.R183Q mutation impairs GTPase activity and maintains Gαq in its GTP–bound, active state 9 . Our laboratory recently showed that the GNAQ p.R183Q mutation is enriched in the endothelial cell population in SWS skin lesions and sporadic capillary malformations 10 . Another group reported GNAQ p.R183Q mutant cells located around blood vessels in port-wine stains 11 .…”

Somatic PIK3CA Mutations are Present in Multiple Tissues of Facial Infiltrating Lipomatosis

“…These same somatic mosaic mutations have been identified in cancers, vascular malformations, and other disorders with overgrowth (4,7,9). In the present study, we sought to determine if overgrowth in patients with FIL was caused by a somatic mutation in one tissue type (subcutaneous adipose) that exerts paracrine effects on neighboring structures (10)or by the presence of mutant cells in each of a patient's overgrown tissues (11).…”

513 GNA14 somatic mutation causes congenital and sporadic vascular tumors by MAPK activation

“…Our identification of GNA14 mutations in KHEs, TAs, and LCHs-three distinct classes of vascular tumors-also highlights the pleiotropy of G aq variants, as seen in GNAQ and GNA11 mutations causing LCHs, PWSs, and NICHs. [10][11][12]16,19 Similarly, activating mutations in HRAS, KRAS, and NRAS also demonstrate phenotypic heterogeneity within vascular anomalies, giving rise to both LCHs and NICHs. 8,9 It remains unclear how identical somatic mutations can give rise to distinct clinical phenotypes.…”

“…This mutation has not been previously identified in vascular tumors, although somatic mutation c.548G>A (p.Arg183Gln) in paralog GNAQ is common in capillary malformations and PWSs and has been found in a single case of secondary LCH arising within a PWS. 8,12,19 A recent survey of 16 congenital hemangiomas identified 12/16 (75%) lesions with GNA11 and GNAQ mutations, but all were Pro or Leu substitutions at Gln209. 10 We further analyzed subjects without a detected mutation.…”