Among all 4 patients with BCD with a homozygous mutation in their CYP4V2 gene, BCD-P1 carries the most common mutation in the CYP4V2 gene: a 17-base deletion in exon 7 (6, 9), while BCD-P4, -P5, and -P6 carry 3 distinct missense mutations, respectively. This evidence concerns the gene CYP4V2 and Bietti crystalline dystrophy.