Clinical manifestation and gene mutation of Bietti crystalline corneoretinal dystrophy

Abstract

Objective To analyze the clinical manifestation and CYP4V2 mutations of Bietti crystalline corneoretinal dystrophy( BCD) families. Methods Total of 234 patients (173 families) diagnosed as BCD were recruited in Peking University Third Hospital from 2010 to 2018.All of the subjects underwent comprehensive eye examinations to observe the clinical manifestations.Blood samples were collected and genomic DNA was extracted.The Sanger sequencing or high- throughput sequencing was applied for CYP4V2 gene mutation analysis.This study was approved by the Ethics Committee of Peking University Third Hospital (NO.2012093). All patients and their family members signed informed consent. Results Some patients manifested the typical phenotype of BCD characterized by yellowish-white crystalline deposits throughout the fundus.However, some patients in advanced stage were easily misdiagnosed as other inherited retinal degeneration because the crystalline deposits diminished or even disappeared.Forty-nine probands in our cohort were misdiagnosed as other inherited retinal degeneration at first visit, with a misdiagnosis rate of 28.3%.Genetic diagnosis results showed that 161 patients carried CYP4V2 mutation, and the positive rate was 93.1%.Eight novel mutations were obtained.The three known mutations c. 802-8 _810del17bp, c.1091-2 A>G and c. 992 A>C accounted for 73.5% of the mutations, which were hotspots in Chinese Han populations for BCD. Conclusions Patients with BCD have characteristic fundus manifestation, but are easily misdiagnosed in advanced stage.Molecular diagnosis is valuable in clinical diagnosis of the disease, thus contribute to the prevention and treatment of the disease.A single hybrid mutation is not enough to lead to BCD.No apparent genotype- phenotype correlation between the CYP4V2 gene and occurrence of BCD is identified. Key words: Gene mutation; Bietti crystalline corneoretinal dystrophy; CYP4V2 gene