CYP4V2 and Bietti crystalline dystrophy: All the BCD patients harbored CYP4V2 mutations, and gene sequencing identified five mutations, including a novel mutation c.219T>A (p. F73L) and four known mutations, c.283G>A (p.G95R), c.802-8_810del17insGC (splicing site), c.1062dupA (p.V355Sfs*4), and c.1091-2A>G (splicing site).