B oon and associates provide important and insightful comments regarding the multifocal vitelliform paravascular retinopathy (MVPR) phenotype. We agree that it is important to consider exposure to mitogen-activated protein kinase (MEK) inhibitor medications and MEK inhibitor–like aromatic amines (apparently a component in hair dyes!) in the differential for vitelliform lesions, although as Boon and associates point out, it is an unlikely cause of MVPR. In our MVPR case series, most patients were healthy without a history of cancer (one patient did note colon cancer in remission and another had monoclonal gammopathy of unknown significance). None of our patients endorsed a history of MEK inhibitor use. In addition, the MVPR lesions were relatively stable, in some cases over several years, and there was no evidence of abnormalities on the electro-oculogram (EOG) in those who were tested.
Genetic testing was completed in 6 (46%) of our subjects with MVPR and was negative for mutations in BEST1, PRPH2, and IMPG1/2. EOG was performed in 3 (23%) patients with MVPR and was normal in all 3 cases. The multifocal vitelliform dystrophy case series by Boon and associates is an important and compelling study. Six (40%) patients in the Boon series did not have a mutation in the BEST1 gene, and 4 (27%) of these non-BEST1–associated patients had normal EOG. It is possible that these non-BEST1 patients with both macular and extramacular paravascular vitelliform lesions may represent the MVPR phenotype. Our case series only included cases with vitelliform lesions exclusively located in the region of the major arcades to avoid overlap with Best disease.
We certainly agree that further investigation of this interesting MVPR phenotype is warranted to more precisely define the spectrum of disease that may or may not include central macular involvement and to ascertain if there is an underlying genetic vs acquired etiology. More rigorous genetic testing including family screening in patients with MVPR may be helpful in this regard. Given that the etiology of MVPR is yet to be elucidated, when evaluating a patient with this phenotype, known causes of genetic and acquired vitelliform dystrophies, especially BEST1, should be excluded.
See the original article for any disclosures of the authors.
CRediT authorship contribution statement
WEILIN SONG: Conceptualization, Data curation, Formal analysis, Investigation, Writing – original draft, Writing – review & editing. DAVID SARRAF: Conceptualization, Data curation, Investigation, Methodology, Supervision, Writing – review & editing.
Conflict of Interest: none.
REFERENCES
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
