Familial uveal melanoma .3. Is the occurrence of familial uveal melanoma coincidental?

Objective: To ascertain whether the familial occurrence of uveal melanoma was coincidental in kindreds in which 1 first-degree relative of the proband had also been affected with primary uveal melanoma. Patients: In a series of 4500 patients with primary uveal melanoma, 17 kindreds were identified in which a first-degree relative of the proband had also been affected with primary uveal melanoma. Design: In the 17 families in which a first-degree relative of the proband had been affected, primary uveal melanoma was classified as familial. In the remaining 4483 families, primary uveal melanoma was classified as sporadic. The expected number of affected first-degree relatives of probands for a family was estimated, assuming an incidence rate of 6 cases per million population per year in each type of family. Results: The expected number of affected first-degree relatives was calculated to be 0.81, with an SE of 0.08, compared with 17 observed affected first-degree relatives (P<.001). Conclusion: Our study provides strong statistical evidence that occurrence of familial uveal melanoma is not coincidental.