BEST1 and Best vitelliform macular dystrophy: To date, nearly 200 disease-causing mutations have been identified in human BEST1 (hBEST1), and the in vitro analysis of their molecular and functional consequences revealed a total loss of Best1 channel activity in ARB or altered anion conductance due to defective intracellular trafficking and protein folding in BVMD [3], [8]–[10].