Clinical and molecular findings in three Japanese patients with crystalline retinopathy

Purpose: To identify CYP4V2 mutations in three unrelated Japanese patients with Bietti crystalline corneoretinal dystrophy (BCD). Methods: The three cases were diagnosed by ophthalmological examinations. All exons and flanking introns were amplified by polymerase chain reaction (PCR). PCR products were analyzed by direct sequencing. RNA was extracted from blood samples and analyzed by reverse transcriptase (RT)-PCR sequencing. Results: Direct PCR sequencing demonstrated a homozygous mutation involving a 17-bp deletion together with a 2-bp insertion (c.802-8del17bp/insGC) in case 1 and case 3, and RT-PCR demonstrated that the complete length of exon 7 was missing; case 2 showed only a heterozygous change in exon 11 with no second mutation. Conclusion: A homozygous mutation was identified in two of the unrelated patients, and only a heterozygous change was detected in the third. These data indicate that c.802-8del17bp/insGC may be a frequent mutation in this gene.