Best's vitelliform dystrophy
Best's vitelliform dystrophy is an autosomal dominant disease that pathologically affects the retinal pigment epithelium and symmetrically affects the macula of patients at a very young age. Visual acuity tends to remain quite good for long periods of time. In the later stages of the disease, atrophic changes of the retinal pigment epithelium or scarring secondary to subretinal neovascular membranes with hemorrhage may cause a loss of central visual acuity. An abnormal diminished light to dark ratio of the electrooculogram is the hallmark of the disease. No other significant ocular abnormalities or systemic problems have been associated with this genetic disorder. No therapy exists for halting the progression of the disease with the possible exception of laser photocoagulation treatment used to ablate subretinal neovascular membranes in an attempt to avoid complications of subretinal hemorrhages. However, an accurate diagnosis and pedigree analysis is important for allowing the physician to perform adequate family and genetic counseling to affected patients.
Available from: Paloma Dominguez Gimenez
- "Histopathologically, BVMD has been shown to manifest as a generalized retinal pigment epithelium (RPE) abnormality associated with lipofuscin accumulation, regions of geographic atrophy, and deposition of abnormal fibrillar material beneath the RPE . In addition, patients are also diagnosed with a decreased electrooculogram (EOG) [3,4]. BVMD is linked to mutations in the Bestrophin-1 gene (BEST1, formerly VMD2) located on chromosome 11 [5,6]. "
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ABSTRACT: Mutations in BEST1 gene, encoding the bestrophin-1 (Best1) protein are associated with macular dystrophies. Best1 is predominantly expressed in the retinal pigment epithelium (RPE), and is inserted in its basolateral membrane. We investigated the cellular localization in polarized MDCKII cells of disease-associated Best1 mutant proteins to study specific sorting motifs of Best1. Real-time PCR and western blots for endogenous expression of BEST1 in MDCK cells were performed. Best1 mutant constructs were generated using site-directed mutagenesis and transfected in MDCK cells. For protein sorting, confocal microscopy studies, biotinylation assays and statistical methods for quantification of mislocalization were used. Analysis of endogenous expression of BEST1 in MDCK cells revealed the presence of BEST1 transcript but no protein. Confocal microscopy and quantitative analyses indicate that transfected normal human Best1 displays a basolateral localization in MDCK cells, while cell sorting of several Best1 mutants (Y85H, Q96R, L100R, Y227N, Y227E) was altered. In contrast to constitutively active Y227E, constitutively inactive Y227F Best1 mutant localized basolaterally similar to the normal Best1 protein. Our data suggest that at least three basolateral sorting motifs might be implicated in proper Best1 basolateral localization. In addition, non-phosphorylated tyrosine 227 could play a role for basolateral delivery.
Available from: Eric H Souied
- "The most determinant symptom of Best VMD is the abnormal EOG with a reduced light-peak to dark-trough ratio combined with a normal ERG [19,20]. Bestrophin 1, the 585-amino acid protein encoded by the BEST1 gene , is a member of the RFP-TM family of proteins, so named for their highly conserved arginine, phenylalanine, proline motif [3,21,22], which appears to exhibit properties of Ca2+-activated Cl− channels [4,23,24]. "
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ABSTRACT: To analyze functional and clinical data of Best vitelliform macular dystrophy (VMD) patients with mutations in the BEST1 gene.
Best VMD patients with BEST1 mutations were evaluated prospectively regarding age, age of onset, best-corrected visual acuity (BCVA), fundus autofluorescence, fluorescein angiography, optical coherence tomography, and electro-oculography. Mutations in BEST1 were established by direct sequencing.
Forty-six eyes of 23 patients (10 male, 13 female) were included in the study. We identified nine different BEST1 mutations (3/9 novel), in ten unrelated families. The age of patients ranged between 3 and 75 years; age of onset varied between 2 and 67 years. BCVA ranged between 20/20 and 20/200. On the basis of fundus biomicroscopy with direct illumination, using one widely accepted classification, the macular lesions could be counted as follows: 1. no lesion (normal fovea): eight eyes, five patients carrying a mutation on the BEST1 gene; 2. previtelliform lesions: six eyes, three affected patients; 3. vitelliform lesions: four eyes, two affected patients; 4. pseudohypopyon: three eyes, three affected patients; 5. vitelliruptive lesions (scrambled egg aspect with dispersion of the vitelliform material without sign of atrophy or fibrosis): ten eyes, six affected patients; 6. atrophic lesions (atrophy with or without residual dispersed material): seven eyes, five patients; 7. fibrotic lesions: eight eyes, five patients. Two patients presented unilateral Best VMD. Both eyes of two patients presented multifocal Best VMD features on fundus examination. Six eyes of four patients have been treated for choroidal neovascularization by thermic photocoagulation [one eye], photodynamic therapy [three eyes], and intravitreal ranibizumab injection [two eyes]. Comparison of interfamilial and intrafamilial clinical data between patients did not reveal differences in age, BCVA, and stage of the disease as evaluated by fundus autofluorescence, fluorescein angiography, and optical coherence tomography (p>0.05). Mean BCVA impairment showed a statistically significant correlation to a more advanced stage of the disease (p<0.001).
BEST1 mutations were not correlated with the severity of the functional and clinical data in the Best VMD patients examined.
Available from: Faisal Abdel Rahman
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