What is Best Vitelliform Macular Dystrophy

Best Vitelliform Macular Dystrophy, also known as Best disease, is a rare inherited eye condition that causes the progressive loss of central vision by damaging the macula, the part of the retina responsible for sharp, detailed sight. It is characterized by the accumulation of a yellowish, egg-yolk-like substance under the retina, which typically leads to vision changes over several decades.

What causes Best Vitelliform Macular Dystrophy?

Best Vitelliform Macular Dystrophy is caused by mutations in the BEST1 gene. This gene provides instructions for creating a protein called bestrophin-1, which regulates the flow of chloride ions in the retinal pigment epithelium (RPE). When this protein is dysfunctional, fluid and debris accumulate under the retina, forming the classic "vitelliform" (egg-yolk) lesion that defines Best Vitelliform Macular Dystrophy. The condition is inherited in an autosomal dominant pattern, meaning a child only needs one copy of the mutated gene from one parent to develop the disorder.

Who is affected by Best Vitelliform Macular Dystrophy?

While the exact global prevalence is unknown, it is estimated to affect between 1 in 10,000 and 1 in 20,000 individuals. Best Vitelliform Macular Dystrophy typically presents in childhood or adolescence, though the severity and age of onset can vary significantly even within the same family. Both males and females are affected equally, and there is no known geographic or ethnic predilection for the condition.

What are the clinical features of Best Vitelliform Macular Dystrophy?

The progression of Best Vitelliform Macular Dystrophy is often categorized into stages based on the appearance of the macula during an eye exam:

• Pre-vitelliform stage: Normal-appearing retina despite the presence of the BEST1 mutation.


• Vitelliform stage: The characteristic yellow, "egg-yolk" lesion forms in the center of the macula.


• Pseudohypopyon stage: The yellow material shifts, creating a horizontal fluid level.


• Atrophic stage: The yellow material is reabsorbed, leaving behind scarring and retinal atrophy, which often leads to significant central vision loss.

How does it differ from other macular conditions?

Unlike Age-Related Macular Degeneration (AMD), which typically occurs in older adults, Best Vitelliform Macular Dystrophy is a genetic, early-onset condition. While peripheral vision usually remains unaffected in Best Vitelliform Macular Dystrophy, the central vision loss can be profound as the disease progresses to the atrophic stage.

Next steps

• Schedule a comprehensive dilated eye exam with a retinal specialist.


• Consult with a clinical geneticist to discuss genetic testing for the BEST1 gene.


• Join the Best Vitelliform Macular Dystrophy community on DiseaseMaps.org to connect with others sharing similar experiences.

Medical disclaimer: This information is for educational purposes only and does not constitute professional medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Best Vitelliform Macular Dystrophy


• Orphanet: Best disease (ORPHA:118)


• OMIM: Bestrophinopathy; BEST1


• American Academy of Ophthalmology (AAO) EyeWiki