BEST1 and MRCS syndrome: Best vitelliform macular dystrophy (BVMD) [3] and autosomal dominant vitreoretinochoroidopathy (ADVIRC) [4] are also associated with mutations in BEST1. Although the functional role of bestrophin-1 within the RPE remains uncertain, with postulated functions as a Ca2+ activated Cl- channel [5], a regulator of voltage gated Ca2+ channels [6], or as a HCO3– channel [7] the study of disease-associated BEST1 variants has helped to elucidate pathogenic mechanisms underlying the bestrophinopathies.