Best disease, also known as Best vitelliform macular dystrophy, is a rare genetic disease in which progressive macular degeneration leads to variable symptoms of impaired vision and visual acuity. The use of specialized ophthalmologic procedures, as well as genetic testing, is necessary to confirm the diagnosis.
Best disease is a genetic disorder of macular degeneration that was described in the literature more than 100 years ago and is commonly termed Best vitelliform macular dystrophy   . The condition stems from mutations in genes that encode bestrophin-1, a calcium-sensitive chloride channel membrane protein in the retinal epithelium, and the clinical presentation depends on the degree of mutation penetrance   . Best disease is typically diagnosed in two age groups - in childhood and in late adolescence/early adulthood, while rare cases have extended the diagnostic window to the fifth decades of life   . The autosomal dominant mode of inheritance seen in this condition implies that a positive family history is the main risk factor . Several studies have illustrated that Best disease follows a progressive clinical course starting with only minor changes in the retinal pigmented epithelium and the absence of symptoms, known as the previtelliform stage . The second stage, termed vitelliform stage, is distinguished by the appearance of single or multiple well-demarcated yellow or orange "egg-yolk" macular lesions that cause symptoms of blurred vision, loss of central vision, and metamorphopsia  . Further stages (pseudohypopyon, vitelliruptive stage, and atrophic stage) denote the progression of macular lesions that will resemble a "scrambled egg", and gradual loss of visual acuity usually ensues in the majority of cases  . In the absence of an early diagnosis, complications such as subretinal hemorrhage and scarring may significantly affect long-term outcomes when it comes to vision .
- Retinal Pigmentation
It is proposed that dysfunction of bestrophin results in abnormal fluid and ion transport by the retinal pigment epithelium, resulting in a weakened interface between the retinal pigment epithelium and photoreceptors. [ncbi.nlm.nih.gov]
Keywords Retinal Pigment Epithelium Macular Degeneration Retinal Pigment Epithelium Cell Bilateral Condition Central Scotoma These keywords were added by machine and not by the authors. [link.springer.com]
- Retinal Scar
RESULTS: An eye from a Best disease donor with a T6R mutation was found to have deposits containing lipid and glycoconjugates within the central retinal scar. These deposits may be remnants of the vitelliform lesion. [ncbi.nlm.nih.gov]
- Visual Acuity Decreased
acuity Decreased clarity of vision 0007663 Subretinal fluid 0031526 Visual impairment Impaired vision Loss of eyesight Poor vision This gene gives the body instructions for making a protein called bestrophin. [rarediseases.info.nih.gov]
- Type A Personality
• CSR typically presents unilaterally in males 25 to 50 years of age and is associated with conditions such as Type A personality, high stress situations, systemic hypertension, hypercortisolism or sleep apnea. 19,12 Although leakage from the choriocapillaris [reviewofoptometry.com]
To make the diagnosis of Best disease, it is necessary to perform a comprehensive clinical workup, starting with a thorough patient history that will note the course and progression of symptoms, as well as the time at which they appeared. Having in mind the autosomal dominant pattern of inheritance, the patient should be inquired about similar symptoms in siblings, parents, or grandparents. On the other hand, a detailed physical examination particularly focused on visual function and capacity, can significantly narrow the differential diagnosis. Specialized studies, however, are necessary to confirm Best disease as the underlying cause. Electrooculography (EOG) is a recommended procedure if clinical suspicion toward Best disease exists, as it reveals abnormally low light peak conductance, but the findings on an electroretinogram (ERG) are almost always within physiological limits   . EOG might be difficult to perform in children, as the procedure requires a high level of cooperation and patience . Furthermore, optical coherence tomography (OCT) might be even more useful, as this non-invasive procedure provides a close view of the retina and its epithelium where pathological changes occur  . Supplementary to ophthalmologic procedures, genetic studies should also be conducted, but their high cost and scarce availability reduce their role in general practice  .
Other Test Results
- Electroretinogram Abnormal
Localization of multifocal electroretinogram abnormalities to the lesion site: findings in a family with Best disease. Arch Ophthalmol. 2006 Nov. 124(11):1593-600. [Medline]. Patrinely JR, Lewis RA, Font RL. [emedicine.com]
Localization of multifocal electroretinogram abnormalities to the lesion site: findings in a family with Best disease. Arch Ophthalmol. 2006; 124 :1593–600. [ PubMed : 17102007 ] Hartzell HC, Qu Z, Yu K, Xiao Q, Chien LT. [ncbi.nlm.nih.gov]
- Low S, Davidson AE, Holder GE, et al. Autosomal dominant Best disease with an unusual electrooculographic light rise and risk of angle-closure glaucoma: a clinical and molecular genetic study. Mol Vis. 2011;17:2272-2282.
- Zhang Q, Small KW, Grossniklaus HE. Clinicopathologic findings in Best vitelliform macular dystrophy. Graefes Arch Clin Exp Ophthalmol. 2011;249(5):745-751.
- Querques G, Zerbib J, Georges A, et al. Multimodal analysis of the progression of Best vitelliform macular dystrophy. Mol Vis. 2014;20:575-592.
- Frennesson CI, Wadelius C, Nilsson SE. Best vitelliform macular dystrophy in a Swedish family: genetic analysis and a seven-year follow-up of photodynamic treatment of a young boy with choroidal neovascularization. Acta Ophthalmol. 2014;92(3):238-242.
- Kay DB, Land ME, Cooper RF, et al. Outer Retinal Structure in Best Vitelliform Macular Dystrophy. JAMA Ophthalmol. 2013;131(9):1207-1215.
- Cohn AC, Turnbull C, Ruddle JB, et al. Best’s macular dystrophy in Australia: phenotypic profile and identification of novel BEST1 mutations. Eye (Lond). 2011;25(2):208-217.
- Ferrara DC, Costa RA, Tsang S, Calucci D, Jorge R, Freund KB. Multimodal fundus imaging in Best vitelliform macular dystrophy. Graefes Arch Clin Exp Ophthalmol. 2010;248(10):1377-1386.