A novel mutation of CYP4V2 gene associated with Bietti crystalline dystrophy complicated by choroidal neovascularization

AIM: To investigate the clinical characteristics and genetic features of a Bietti crystalline dystrophy (BCD) proband in a Chinese family. METHODS: A Chinese female diagnosed with BCD complicated by bilateral choroidal neovascularization (CNV) and her parents underwent complete ophthalmic examinations, including fundus autofluorescence (AF), fundus photography (FP), fundus fluorescein angiography (FFA), visual field testing, full-field electroretinography (ERG), optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). The sequencing of the CYP4V2 gene was performed to the whole family. RESULTS: Bilateral tiny glittering crystal-like deposits and differing extent of atrophy of the retinal pigment epithelium (RPE) were found in the posterior pole of her fundus. The diffuse hypo-fluorescence shown on AF images and window defects shown on FFA both indicated the atrophy of the RPE and choriocapillaris. OCT showed the thinning of the RPE and choriocapillaris layer, ellipsoid zone (EZ) band defect and CNV in both eyes. OCTA images proofed bilateral type 2 CNV. The visual field test showed central and paracentral scotoma. ERG showed a slightly decreased b-wave in scotopic ERG. Gene sequencing identified three mutations of the CYP4V2 gene, c.802_807del, c.810delT, and c.1388G>A. The mutation c.1388G>A was a novel substitution mutation. CONCLUSION: The novel mutation c.1388G>A may be a possible cause that could induce the clinical phenotype of BCD.