Recently, a better understanding of the molecular pathology of BEST1-related phenotypes was achieved by demonstrating that BEST1 gene defects in BVMD and ARB trigger a strong reduction of BEST1-mediated anion transport function compared to control, while ADVIRC mutations cause an increased anion permeability suggesting a stabilized open state condition of channel gating. Here, BEST1 is linked to Best vitelliform macular dystrophy.