To further validate the cellular phenotype that we found in BCD patient–specific iRPE cells, we established an isogenic iPSC line from BCD-P1 with a CRISPR/Cas9 genome editing system and successfully repaired in both alleles the homozygous 17 bp deletion mutation c.802-8_810del17insGC in the CYP4V2 gene, the most common mutation among patients with BCD (9, 17) (Supplemental Figure 3A). Here, CYP4V2 is linked to Bietti crystalline corneoretinal dystrophy.