Somatic Activating Mutations in GNAQ and GNA11 Are Associated with Congenital Hemangioma

Abstract

Congenital hemangioma is a rare vascular tumor that forms in utero. Postnatally, the tumor either involutes quickly (i.e., rapidly involuting congenital hemangioma [RICH]) or partially regresses and stabilizes (i.e., non-involuting congenital hemangioma [NICH]). We hypothesized that congenital hemangiomas arise due to somatic mutation and performed massively parallel mRNA sequencing on affected tissue from eight participants. We identified mutually exclusive, mosaic missense mutations that alter glutamine at amino acid 209 (Glu209) in GNAQ or GNA11 in all tested samples, at variant allele frequencies (VAF) ranging from 3% to 33%. We verified the presence of the mutations in genomic DNA using a combination of molecular inversion probe sequencing (MIP-seq) and digital droplet PCR (ddPCR). The Glu209 GNAQ and GNA11 missense variants we identified are common in uveal melanoma and have been shown to constitutively activate MAPK and/or YAP signaling. When we screened additional archival formalin-fixed paraffin-embedded (FFPE) congenital cutaneous and hepatic hemangiomas, 4/8 had GNAQ or GNA11 Glu209 variants. The same GNAQ or GNA11 mutation is found in both NICH and RICH, so other factors must account for these tumors' different postnatal behaviors.

A somatic GNA11 mutation is associated with extremity capillary malformation and overgrowth

“…Here, we report a second gene responsible for this lesion, GNA11. Consistent with our finding, functional overlap or redundancy between GNAQ and GNA11 also have been observed in uveal melanoma [7], phakomatosis pigmentovascularis [8], melanomas associated with blue nevi [9], and congenital hemangiomas [4]. Although GNA14 shares ~80% amino acid identity with GNAQ and GNA11, and can cause vascular tumors [10], we did not identify GNA14 mutations in capillary malformations.…”

“…We excluded false positive results, which could occur if our ddPCR assay had poor specificity, by not finding a GNA11 or GNA14 mutation in affected tissue from patients with capillary malformations caused by GNAQ mutations. To determine if other mutations in GNA11 account for the ddPCR-negative samples, we performed single molecule molecular inversion probe sequencing (smMIP-seq) [4] in 4 specimens that had sufficient DNA. No additional GNA11 mutations were identified.…”

“…In a previous study we were unable to identify GNAQ mutations in a cohort of capillary malformations involving the lower extremity [3]. We hypothesized that somatic GNA11 mutations would also cause capillary malformations because GNAQ and GNA11 share > 90% amino acid identity, and mutations affecting a different amino acid residue p.Gln209 in either GNAQ or GNA11 cause congenital hemangiomas [4]. …”

Mice maintain predominantly maternal Gαs expression throughout life in brown fat tissue (BAT), but not other tissues

“…The parental contribution to Gαs transcription was assessed also by ddPCR [20] taking advantage of the same C/G polymorphism in Gnas exon 11. The forward primer for this approach (f5) anneals to the 3′ end of exon 10, while the reverse primer (r3) anneals to sequences derived from exons 11 and 12 to generate an amplicon of 106 bp (see Fig.…”

Applicability of digital PCR to the investigation of pediatric-onset genetic disorders

“…dPCR shows somatic loss of one wild-type NF1 ( neurofibromin-1 ) allele within a malignant melanoma of a patient with neurofibromatosis type I [30]. Congenital hemangiomas are rare vascular tumors that develop prenatally as a result of somatic mutations; ddPCR can detect subclonal mutations in GNAQ ( GNAQ(E209L) and GNAQ(E209P) ) and GNA11 ( G protein subunit α 11 , G 11 α; GNA11(E209L) ) in these tumors [31]. Within tumors, dPCR is a powerful tool to detect subclonal mutations affecting prognosis as well as loss of heterozygosity.…”