ACLINICAL AND GENETIC FEATURES IN CHINESE BIETTI CRYSTALLINE DYSTROPHY (BCD) FAMILIES WITH CYP4V2 MUTATIONS

Bietti crystalline dystrophy (BCD) is a rare autosomal recessive inherited disorder characterized by crystals in retinal pigment epithelium. The purpose of this study was to identify the genetic defect in Chinese families with BCD and analyze their clinical features. The clinical examination and genetic studies were performed in three BCD families at Tongji University Hospital. Eye examination included fundus fluorescein angiography, slit lamp, fundus photograph, optical coheres tomography and visual acuity examination has been carried out. Blood samples were collected from three pro-bands and their family members. Genomic DNA extracted from whole blood used for polymerase chain reaction (PCR) to identify genetic defect. Fundus examination revealed that the presence of tiny yellowish-sparkling crystals at the posterior pole of the fundus and atrophy of the retinal pigment epithelium in some patients. The PCR results also showed that three different mutations in the three families including Family C with compound heterozygous mutations of deletion c.802-8_810del17bpinsGT and insertion c.1062dupA, Family B with compound heterozygous mutations of a splicing mutation c.1091-2A>G and deletion mutation c.802-8_810del17bpinsGC and Family A with homozygous deletion mutation c.802-8_810del17bpinsGC. In this study, the PCR result also identified CYP4V2 as the disease causative gene in three Chinese families with BCD. Overall, these findings broaden the spectrum of CYP4V2 mutations that cause BCD and characterize phenotypic features of the disease in Chinese families.