Novel CYP4V2 mutations associated with Bietti crystalline corneoretinal dystrophy in Chinese patients

<b>AIM:</b> To analyze the <i>CYP4V2</i> mutations in five unrelated Chinese patients with Bietti crystalline corneoretinal dystrophy (BCD) and to provide clinical features of these patients. BCD is a rare monogenic autosomal recessively inherited disorder characterized by the presence of crystals in the retina and retinal pigment epithelium atrophy. Mutations in the <i>CYP4V2</i> gene have been found to be causative for BCD.<b>METHODS:</b>Ophthalmic examinations were carried out in the affected individuals. Peripheral blood samples were collected and genomic DNA was extracted. All exons and flanking intronic regions of the <i>CYP4V2</i> gene were amplified with polymerase chain reaction and screened for mutations by direct DNA sequencing. One hundred control chromosomes were also screened to exclude nonpathogenic polymorphisms.<b>RESULTS:</b> Fundus examination revealed the presence of tiny yellowish-sparkling crystals at the posterior pole of the fundus and atrophy of the retinal pigment epithelium in all patients. Choroid neovascularization was noted in one patient. Five different <i>CYP4V2</i> mutations were identified, including two missense mutations (p.F73L, p.R400H), two splice site mutations (c.802-8_810del17insGC, c.1091-2A&gt;G), and one single base-pair deletion (p.T479TfsX7 or c.1437delC). The two splice site mutations were identified in three of the patients with BCD. Mutation p.T479TfsX7 was a novel mutation not observed in any of 100 ethnically matched control chromosomes.<b>CONCLUSION:</b> Mutation c.802-8_810del17insGC and c.1091-2A&gt;G are common mutations in Chinese patients with BCD. Our results expand the allelic heterogeneity of BCD