Bietti's crystalline dystrophy (Bietti crystalline dystrophy) - Gen CYP4V2

The Bietti's crystalline dystrophy, also known as crystalline retinopathy Bietti, is a process that leads to the accumulation of deposits similar lipid crystals retina. These deposits damage the retina, causing a progressive loss of vision.

People with crystalline dystrophy Bietti usually begin to suffer vision problems in the teens or twenties. These problems include reduced visual acuity and night blindness. They usually suffer a loss of visual field, most commonly peripheral vision. In addition, color vision may also be affected.

Vision problems may worsen at different rates in each eye, and the severity and progression of symptoms varies widely among affected individuals, even within the same family. However, most of those affected lose vision completely around forty or fifty years. Most individuals retain some degree of vision, usually in the center of the visual field, although this is often blurred and can not be corrected with contact lenses.

This process is due to mutations in the gene CYP4V2 (cytochrome P450 family 4 subfamily V member 2), located on the long arm of chromosome 4 (4q35.2), encoding a member of the family of cytochrome P450 enzymes. These enzymes are involved in the formation and decomposition of various molecules and chemicals within cells. The CYP4V2 enzyme is involved in fatty acid oxidation, but the specific enzyme function is not well understood.

They have identified at least 43 genetic mutations in people with CYP4V2 Bietti's crystalline dystrophy. These mutations correspond to: missense mutations (32), and cutting mutations -splicing- connection (6), small deletions (3), small insertions (1) and insertions / deletions small (1). These mutations cause changes in the structure of the enzyme CYP4V2 so that reduced or eliminated their activity. Although it is likely that mutations affecting lipid degradation, the way these mutations give rise to specific signs and symptoms of the disease is unknown. For unknown reasons, the severity of the signs and symptoms differs significantly among individuals with the same genetic mutation CYP4V2.

This disease is inherited in an autosomal recessive pattern, which means that both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.  

Tests in IVAMI: in IVAMI perform detection of mutations associated with Bietti's crystalline dystrophy, by complete PCR amplification of exons CYP4V2 gene, and subsequent sequencing.


Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated card blood sample   desiccated (IVAMI can mail the card to deposit the blood sample).