This discrepancy may arise from the fact that patients who are clinically diagnosed with conditions that can resemble the initial or final stages of Best disease, such as age-related macular degeneration, RP, cone–rod dystrophies, and AVMD, are typically not suspected to have Best disease and consequently do not undergo genetic testing for mutations in BEST1 (Fig. 1A; Supplementary Tables S2, S5), which could result in an underdiagnosis of BEST1 mutations. Here, BEST1 is linked to retinitis pigmentosa 1.