Bietti's crystalline dystrophy explained

Bietti's Crystalline Dystrophy
Synonyms:	Bietti crystalline corneoretinal dystrophy

Bietti's crystalline dystrophy (BCD) is a rare autosomal recessive^[1] eye disease named after G. B. Bietti.^[2]

BCD is a rare disease and appears to be more common in people with Asian ancestry.^{[3] [4] [5]}

Presentation

Symptoms of BCD include:

• Crystals in the cornea (the clear covering of the eye)
• Yellow, shiny deposits on the retina
• Progressive atrophy of the retina, choriocapillaries and choroid (the back layers of the eye). This tends to lead to progressive night blindness and visual field constriction.

Genetics

BCD is inherited in an autosomal recessive manner.^[1] This means the defective gene responsible for the disorder is located on an autosome, and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder.

BCD is associated with mutations in the CYP4V2 gene.^[1] The nematode C. elegans has a duplicated gene (cyp31A2 and cyp31A3) that are orthologous of the human gene.These genes code for cytochrome P450s involved in fatty acid synthesis.^[6]

Treatment

At this time, there is no treatment for BCD. Genetic studies are being conducted to find treatments for patients with BCD.^[7]

Notes and References

1. Li A, Jiao X, Munier FL, Schorderet DF, Yao W, Iwata F, Hayakawa M, Kanai A, Shy Chen M, Alan Lewis R, Heckenlively J, Weleber RG, Traboulsi EI, Zhang Q, Xiao X, Kaiser-Kupfer M, Sergeev YV, Hejtmancik JF . Bietti crystalline corneoretinal dystrophy is caused by mutations in the novel gene CYP4V2 . Am. J. Hum. Genet. . 74 . 5 . 817–26 . 2004 . 15042513 . 1181977 . 10.1086/383228 .
2. Bietti G . Ueber familiaeres Vorkommen von 'Retinitis punctata albescens' (verbunden mit 'Dystrophia marginalis cristallinea corneae'), Glitzern des Glaskoerpers und anderen degenerativen Augenveraenderungen . . 99 . 737–757 . 1937 .
3. Furusato E, Cameron JD, Chan CC . Evolution of Cellular Inclusions in Bietti's Crystalline Dystrophy . Ophthalmol Eye Dis . 2010 . 2 . 9–15 . 2010 . 21359135 . 3045089 . 10.4137/OED.S2821 .
4. Sahu. DK. Rawoof. AB. 2002. Bietti's crystalline dystrophy. Indian J Ophthalmol. 50. 4. 330–332. Medknow. 12532504.
5. Welch. RB. 1977. Bietti's tapetoretinal degeneration with marginal corneal dystrophy crystalline retinopathy. Trans Am Ophthalmol Soc. 75. 164–79. 306693 . 1311548.
6. Benenati G, Penkov S, Müller-Reichert T, Entchev EV, Kurzchalia TV . Two cytochrome P450s in Caenorhabditis elegans are essential for the organization of eggshell, correct execution of meiosis and the polarization of embryo . Mech Dev . May–Jun 2009 . 126 . 5–6 . 382–93 . 19368796 . 10.1016/j.mod.2009.02.001 . 17220562 . free .
7. Web site: Facts About Bietti's Crystalline Dystrophy National Eye Institute . nei.nih.gov . 18 October 2018 . en . 18 October 2018 . https://web.archive.org/web/20181018122600/https://nei.nih.gov/health/biettis/bietti . dead .