Bietti crystalline corneoretinal dystrophy (BCD) is an autosomal recessive eye disorder characterized by the presence of yellow-white crystalline deposits on the retina, retinal pigment epithelial atrophy and choroidal sclerosis. BCD is progressive disease with an average onset age of 29.3 years. In the course of BCD, patients develop night blindness, paracentral scotomata, and peripheral vision loss which eventually advances to legal blindness.
Mutations in the CYP4V2 (Cytochrome P450 Family 4 Subfamily V Member 2) gene has been identified to cause BCD. Although the genetic aetiology of BCD is not clearly understood, inactivating mutation in CYP4V2 is considered to impair the protein product associated with fatty acid and steroid metabolism in the eye.
