Crystal deposits on the lens capsules in Bietti crystalline corneoretinal dystrophy associated with a mutation in the CYP4V2 gene: Case Series

Purpose: We report a patient (Case 1) with Bietti crystalline corneoretinal dystrophy (BCD) associated with previously unknown findings of crystal-like deposits on the anterior and posterior lens capsules. This patient is one of four (Cases 1-4) in whom we have found BCD associated with the same mutation in the CYP4V2 gene. Methods: We present a case report with molecular diagnosis. A 45-year-old man (Case 1) was referred to our clinic with complaints of gradual progression of visual disturbances and night blindness. His visual acuity was limited to hand movement bilaterally. Slit-lamp biomicroscopy disclosed glistening, crystal-like deposits on the anterior and posterior lens capsules, as well as on the corneal stroma near the corneoscleral limbus. No such deposit was found in the lens stroma. Fundus examination disclosed profound chorioretinal atrophy with scarce crystal deposits. Full-field electroretinography showed extinguished responses of isolated rods, isolated cones, and mixed rods and cones. Results: Molecular genetic analysis revealed that the subject had a homozygous mutation in the CYP4V2 gene (IVS6-8delTCATACAGGTCATCGCG/insGC), which is most commonly found in Japanese patients with BCD. Three other cases (Cases 2-4) of BCD associated with the same mutation did not show such crystal-like deposits on the lens surface. Conclusions: Although their exact origin remains unknown, crystal-like deposits may appear on the lens capsule of patients with BCD associated with a mutation in the CYP4V2 gene.