Association of Somatic GNAQ Mutation With Capillary Malformations in a Case of Choroidal Hemangioma

Question  Is the GNAQ R183Q mutation present in the choroidal vessels of a patient with Sturge-Weber syndrome and choroidal hemangioma?

Findings  In this case study, laser-capture microdissection followed by droplet digital polymerase chain reaction analysis showed that the GNAQ R183Q mutation was present in the patient’s choroidal tissue. The tissue tested negative for GNAQ mutations found in congenital hemangioma and did not express the infantile hemangioma marker glucose transporter-1.

Meaning  Based on a single case, a choroidal hemangioma was identified as a choroidal capillary malformation, laying the foundation to accurately classify this vascular anomaly to better guide treatment decisions.

Importance  Choroidal hemangiomas are defined by a thickened choroid owing to vessel overgrowth, which may increase the intraocular pressure and lead to glaucoma. Choroidal hemangioma and glaucoma often co-occur in patients with Sturge-Weber syndrome, a rare neurocutaneous disorder characterized by capillary malformations.

Objective  To determine whether the mutation found in most capillary malformations, GNAQ R183Q (c.548G>A), was present in the choroidal hemangioma of a patient with Sturge-Weber syndrome.

Design, Setting, and Participant  Using laser-capture microdissection, choroidal blood vessels were isolated from paraffin-embedded tissue sections, and genomic DNA was extracted for mutational analysis. Choroidal sections were analyzed in parallel. A patient with choroidal hemangioma and Sturge-Weber syndrome who had undergone enucleation was analyzed in this study at Boston Children’s Hospital. Negative controls were choroidal tissue from an eye with retinoblastoma and unaffected lung tissue; brain tissue from a different patient with Sturge-Weber syndrome served as a positive control. Infantile hemangioma was analyzed as well. Data were analyzed in 2018.

Main Outcomes and Measures  The mutant allelic frequency of GNAQ R183 and GNAQ Q209L/H/P was determined by droplet digital polymerase chain reaction on isolated genomic DNA. The infantile hemangioma marker glucose transporter-1 was visualized by immunofluorescent staining of tissue sections.

Results  The GNAQ R183Q mutation was present in the patient’s choroidal vessels (21.1%) at a frequency similar to that found in brain tissue from a different patient with Sturge-Weber syndrome (25.1%). In contrast, choroidal vessels from a case of retinoblastoma were negative for the mutation (0.5%), as was lung tissue (0.2%). The patient’s choroidal tissue was negative for the 3 GNAQ mutations associated with congenital hemangioma and for the infantile hemangioma marker glucose transporter-1.

Conclusions and Relevance  The results suggest that a more accurate description for choroidal hemangioma in patients with Sturge-Weber syndrome is choroidal capillary malformation. This finding may explain why propranolol, used to treat infantile hemangiomas, has been largely ineffective in patients with choroidal hemangioma. Further studies are needed to corroborate this finding.