Background and aims We aimed to determine the frequency of von Hippel-Lindau disease (vHL) as the underlying cause of retinal hemangioblastoma and to estimate retinal hemangioblastoma incidence and prevalence in a national cohort study.

Methods Through the national patient register and vHL research database, we identified 81 patients diagnosed with a retinal hemangioblastoma in Denmark between 1977 and 2014. Consent was obtained for 54 living and 10 deceased patients with retinal hemangioblastoma. For each participant, we collected medical records and family information. Almost all (63 of 64) participants were or had previously been tested for mutations in the VHL gene.

Results Overall, 84% of the participants (54 of the 64) had vHL. Compared with the non-vHL patients, the vHL patients had their first retinal hemangioblastoma at a younger age (22.5 vs 40 years), and were more likely to have an asymptomatic first hemangioblastoma (80% vs 20%). Overall, 76% (41 of 54) of the vHL patients had a family history of vHL, while none of the patients without vHL did. Despite the rarity of the disease, on average more than eight new tumours are diagnosed each year due to multiple tumour development in vHL patients. The estimated prevalence of patients with retinal hemangioblastoma was up to 1 in 73 080 individuals.

Conclusion In the first national study in which almost all participants were genetically tested, vHL was the underlying cause of retinal hemangioblastoma in 84% of cases; more often than previously reported. We recommend that genetic and clinical vHL screening should be performed in all patients with retinal hemangioblastoma