Phenotypic variability in a French family with a novel mutation in the BEST1 gene causing multifocal best vitelliform macular dystrophy.
(3/16)
AIMS: To describe genetic and clinical findings in a French family affected by best vitelliform macular dystrophy (BVMD). METHODS: We screened eight at-risk members of a family, including a BVMD-affected proband, by direct sequencing of 11 bestrophin-1 (BEST1) exons. Individuals underwent ophthalmic examination and autofluorescent fundus imaging, indocyanine green angiography, electro-oculogram (EOG), electroretinogram (ERG), multifocal ERG, optical coherence tomography (OCT), and where possible, spectral domain OCT. RESULTS: The sequence analysis of the BEST1 gene revealed one previously unknown mutation, c.15C>A (p.Y5X), in two family members and one recently described mutation, c.430A>G (p.S144G), in five family members. Fundus examination and electrophysiological responses provided no evidence of the disease in the patient carrying only the p.Y5X mutation. Three patients with the p.S144G mutation did not show any preclinical sign of BVMD except altered EOGs. Two individuals of the family exhibited a particularly severe phenotype of multifocal BVMD-one individual carrying the p.S144G mutation heterozygously and one individual harboring both BEST1 mutations (p.S144G inherited from his mother and p.Y5X from his father). Both of these family members had multifocal vitelliform autofluorescent lesions combined with abnormal EOG, and the spectral domain OCT displayed a serous retinal detachment. In addition, ERGs demonstrated widespread retinal degeneration and multifocal ERGs showed a reduction in the central retina function, which could be correlated with the decreased visual acuity and visual field scotomas. CONCLUSIONS: A thorough clinical evaluation found no pathological phenotype in the patient carrying the isolated p.Y5X mutation. The patients carrying the p.S144G variation in the protein exhibited considerable intrafamilial phenotypic variability. Two young affected patients in this family exhibited an early onset, severe, multifocal BVMD with a diffuse distribution of autofluorescent deposits throughout the retina and rapid evolution toward the loss of central vision. The other genetically affected relatives had only abnormal EOGs and displayed no or extremely slow electrophysiological evolution. (+info)
The spectrum of subclinical Best vitelliform macular dystrophy in subjects with mutations in BEST1 gene.
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Clinical evaluation of two consanguineous families with homozygous mutations in BEST1.
(6/16)
PURPOSE: To describe the clinical and genetic findings in two consanguineous families with Best vitelliform macular dystrophy (BVMD) and homozygous mutations in the bestrophin-1 (BEST1) gene. METHODS: Ophthalmologic examination was performed in eight members of two families originating from Spain and Denmark. Mutation screening was performed using the Vitelliform Macular Dystrophy mutation array from Asper Biotech, and by the directed genomic sequencing of BEST1. RESULTS: Two homozygous mutations were detected in these families. Mutation c.936C>A (p.Asp312Glu) has been reported previously in a Danish family; here, we describe four additional individuals in this family demonstrating findings compatible with a severe dominant BVMD, albeit with reduced penetrance in heterozygotes. In the Spanish family, a novel homozygous missense mutation in exon 4, c.388 C>A (p.Arg130Ser), was identified in the siblings. Homozygous siblings demonstrated evidence of multifocal vitelliform retinopathy, whereas heterozygous family members presented findings ranging from isolated reduction of the electrooculogram Arden ratio to normal values on all clinical parameters. CONCLUSIONS: As demonstrated in these consanguineous families, a great clinical variability is associated with homozygous mutations in BEST1, ranging from severe dominant BVMD with reduced penetrance in heterozygotes to autosomal recessive bestrophinopathy. (+info)
Autosomal dominant Best disease with an unusual electrooculographic light rise and risk of angle-closure glaucoma: a clinical and molecular genetic study.
(7/16)
PURPOSE: To describe the clinical and molecular characteristics of two families with autosomal dominant Best disease and atypical electrooculography (EOG). METHODS: Four affected individuals from two families were ascertained. Detailed ophthalmic examinations, refraction, and biometry (anterior chamber depth [ACD] and axial length [AL]), gonioscopy, optical coherence tomography of the anterior segment and retina, retinal imaging, and electrophysiological assessment were performed. Arden ratios from EOG testing were calculated by direct measurement of the light peak to dark trough amplitudes. Mutations in bestrophin 1 (BEST1) were identified by bidirectional Sanger sequencing. In family 1, segregation of BEST1 alleles was performed by assaying four microsatellite markers (D11S935, D11S4102, D11S987, and D11S4162) that flank BEST1. RESULTS: The proband from family 1 (three of four siblings affected with Best disease) was 42 years old with bilateral macular vitelliform lesions, advanced angle closure glaucoma (ACG), a normal electroretinogram, and no EOG light rise. Her 44-year-old brother had similar fundus appearances and an EOG light rise of 170%. Their 48-year-old sister had a normal left fundus, whereas the right fundus showed a vitelliform lesion and subretinal thickening. There was no EOG light rise detectable from either eye. Mutation analysis of BEST1 showed all affected siblings to be heterozygous for a missense mutation, c.914T>C, p.Phe305Ser. Their unaffected sister had an EOG light rise of 200%, a normal fundus appearance, and did not harbor the BEST1 mutation. Haplotype analysis of family 1 showed that the affected brother with the 170% EOG light rise had inherited the same nondiseased parental BEST1 allele as his unaffected sister. The other two affected sisters with undetectable EOG light rises shared a different nondiseased parental BEST1 allele. An unrelated 53-year-old female carrying the same c.914T>C, p.Phe305Ser mutation showed typical features of Best disease and an EOG light rise of 180%. All four siblings from family 1 had shorter axial biometry (ACD range 2.06-2.74 mm; AL range 20.46-22.60 mm) than the normal population, contributing to their risk of ACG development. Proband 2 had deeper ACDs (2.83 mm OD and 2.85 mm OS), but similar ALs (21.52 mm OD and 21.42 mm OS) compared to family 1. She had no gonioscopic evidence of angle closure. CONCLUSIONS: A near normal EOG light rise is uncommon in molecularly confirmed Best disease, and in the present report is associated with the same mutation in two families, suggesting a specific role for this amino acid in the retinal pigment epithelium dysfunction associated with this disorder. Haplotype analysis in family 1 was consistent with an effect of the nondisease allele in mediating the presence of an EOG light rise. Clinical assessment of ACG risk is recommended for BEST1 mutation carriers and their first degree relatives. (+info)
Ocular phenotypes associated with biallelic mutations in BEST1 in Italian patients.
(8/16)
PURPOSE: To report on the phenotype and the genotype of Italian patients carrying BEST1 mutations on both alleles. METHODS: Five Italian patients from four independent pedigrees with retinal dystrophy associated with biallelic BEST1 variants were recruited from different parts of Italy. Molecular genetic analysis of the BEST1 gene was performed with direct sequencing techniques. All the subjects included in the study were clinically evaluated with a standard ophthalmologic examination, fundus photography, optical coherence tomography scan, and electrophysiological investigations. RESULTS: Six BEST1 variants were identified. Three, c.1699del (p.Glu557AsnfsX52), c.625delAAC (p.Asn179del), and c.139C>T (p.Arg47Cys), were novel, and three had already been reported in the literature, c.301C>A(p.Pro101Thr), c.934G>A (p.Asp312Asn), and c.638A>G (p.Glu213Gly). Four were missense mutations, and two were deletions. Only one BEST1 mutation was located within one of the four mutational clusters described in typical autosomal dominant Best vitelliform macular dystrophy (BVMD). Four patients showed a BVMD phenotype while one patient presented a clinical picture consistent with autosomal recessive bestrophinopathy (ARB). CONCLUSIONS: Biallelic BEST1 sequence variants can be associated with at least two different phenotypes: BVMD and ARB. The phenotypic result of the molecular changes probably depends on the characteristics and the combination of the different BEST1 mutations, but unknown modifying factors such as other genes or the environment may also play a role. (+info)