Case #72: A Family of Bestrophinopathies – Page 5 of 76

BEST1 Phenotype Variance⁴

BEST1 mutations show variable expression and incomplete penetration which accounts for the variance of phenotypes seen with the same genetic mutation.

It has also been proposed that unknown factors such as genetic modifiers, Best1 protein interactors, and environmental factors may also be responsible for such variability in clinical presentation³.

It is widely known that a BEST1 mutation can be the same among unrelated and/or familial individuals but there are significant phenotype differences including age of onset, disease progression and final visual acuity, and the clinical findings associated with the same BEST1 mutation¹.

The series of cases to follow are a family with various phenotypes of bestrophinopathy. Most have the same genetic defect, but all are clinically different in presentation, symptoms, and functional vision.