TUBB4B gene mutation in Leber phenotype of congenital amaurosis syndrome associated with early-onset deafness.

Beta-tubulin 4B isotype is one of the subunits of microtubules encoded by TUBB4B gene on chromosome 9, which is responsible for the maintenance of microtubule stability. In humans, mutations in microtubule-encoding genes have been associated with several tubulinopathies with very heterogeneous symptoms. So far, only two missense mutations in TUBB4B gene have been found to have pathological implications in this disorder. Here we report a Hungarian family with three affected members, mother and her 12- and 14-year-old children, who suffer from ophthalmologic and hearing impairments probably due to c.1171C > T missense variant in the TUBB4B gene. The presented case is the second report, and unique in the literature because of three affected family members carrying the same mutation and the family provides evidence for a quite similar but not identical phenotype of LCAEOD in subjects carrying this mutation.

Myopia and Late-Onset Progressive Cone Dystrophy Associate to LVAVA/MVAVA Exon 3 Interchange Haplotypes of Opsin Genes on Chromosome X.

Purpose: Rare interchange haplotypes in exon 3 of the OPN1LW and OPN1MW opsin genes cause X-linked myopia, color vision defect, and cone dysfunction. The severity of the disease varies on a broad scale from nonsyndromic high myopia to blue cone monochromatism. Here, we describe a new genotype-phenotype correlation attributed to rare exon 3 interchange haplotypes simultaneously present in the long- and middle-wavelength sensitive opsin genes (L- and M-opsin genes). Methods: A multigenerational family with X-linked high myopia and cone dystrophy was investigated. Results: Affected male patients had infantile onset myopia with normal visual acuity and color vision until their forties. Visual acuity decreased thereafter, along with the development of severe protan and deutan color vision defects. A mild decrease in electroretinography response of cone photoreceptors was detected in childhood, which further deteriorated in middle-aged patients. Rods were also affected, however, to a lesser extent than cones. Clinical exome sequencing identified the LVAVA and MVAVA toxic haplotypes in the OPN1LW and OPN1MW opsin genes, respectively. Conclusion: Here, we show that LVAVA haplotype of the OPN1LW gene and MVAVA haplotype of the OPN1MW gene cause apparently nonsyndromic high myopia in young patients but lead to progressive cone-rod dystrophy with deuteranopia and protanopia in middle-aged patients corresponding to a previously unknown disease course. To the best of our knowledge, this is the first report on the joint effect of these toxic haplotypes in the two opsin genes on chromosome X.

Stromal Cell-Derived Factor 1 Polymorphism in Retinal Vein Occlusion.

BACKGROUND: Stromal cell-derived factor 1 (SDF1) has crucial role in the regulation of angiogenesis and ocular neovascularisation (NV). The purpose of this study was to evaluate the association between SDF1-3'G(801)A polymorphism and NV complications of retinal vein occlusion (RVO). METHODS: 130 patients with RVO (median age: 69.0, range 35-93 years; male/female- 58/72; 55 patients had central RVO, 75 patients had branch RVO) were enrolled in this study. In the RVO group, 40 (30.8%) patients were diagnosed with NV complications of RVO and 90 (69.2%) patients without NVs. The median follow up period was 40.3 months (range: 18-57 months). The SDF1-3'G(801)A polymorphism was detected by PCR-RFLP. Allelic prevalence was related to reference values obtained in the control group consisted of 125 randomly selected, age and gender matched, unrelated volunteers (median age: 68.0, range 36-95 years; male/female- 53/72). Statistical analysis of the allele and genotype differences between groups (RVO patients vs controls; RVO patients with NV vs RVO patients without NV) was determined by chi-squared test. P value of <0.05 was considered statistically significant. RESULTS: Hardy-Weinberg criteria was fulfilled in all groups. The SDF1-3'G(801)A allele and genotype frequencies of RVO patients were similar to controls (SDF1-3'A allele: 22.3% vs 20.8%; SDF1-3'(801)AA: 5.4% vs 4.8%, SDF1-3'(801)GG: 60.8% vs 63.2%). The frequency of SDF1-3'(801)AA and SDF1-3'(801)GA genotypes, as well as the SDF1-3'(801)A allele frequency were higher in RVO patients with NV versus in patients without NV complication (SDF1-3'(801)AA+AG genotypes: 57.5% vs 31.1%, p = 0.008; SDF1-3'(801)A allele: 35.0% vs 16.7%, p = 0.002) or versus controls (SDF1-3'(801)AA+AG genotypes 57.5% vs 36.8%, p = 0.021; SDF1-3'(801)A allele: 35.0% vs 20.8% p = 0.01). Carrying of SDF1-3'(801)A allele increased the risk of neovascularisation complications of RVO by 2.69 (OR, 95% CI = 1.47-4.93). CONCLUSION: These findings suggest that carrying SDF1-3'(801)A allele plays a role in the development of neovascular complications in retinal vein occlusion.

Leber congenital amaurosis: first genotyped Hungarian patients and report of 2 novel mutations in the CRB1 and CEP290 genes.

PURPOSE: To introduce the first Hungarian patients with genetically defined Leber congenital amaurosis (LCA) and to report 2 novel mutations. METHODS: Seven otherwise healthy patients (4-29 years, 5 male and 2 female) who had an onset of severe visual impairment before age 2 years were investigated. The diagnosis was established in all individuals by medical history, funduscopy, and full-field electroretinogram (ERG). Ocular examination included visual acuity testing, digital fundus photography, and in 6 patients retinal imaging with optical coherence tomography (OCT). Arrayed primer extension microarray screening was performed in all probands. In 2 patients, further Sanger sequencing and targeted next-generation sequencing revealed the second disease allele. RESULTS: A cone-rod type LCA was revealed in 4 patients and a rod-cone type disease in 3 patients. Five patients presented with maculopathy. Optical coherence tomography (OCT) imaging showed diffuse retinal thickening in 3 probands with severe macular atrophy in one. Full-field ERGs were undetectable or residual in all patients. Genetic screening revealed AIPL1, CRB1, and CEP290 gene-related pathology in 6 patients; in 1 proband, no mutation was found. Three homozygous and 3 compound heterozygous mutations were identified. Two novel variants were detected: c.2536G>T (p.G846X) in the CRB1 gene and c.4929delA (p.Lys1643fsX2) in the CEP290 gene. CONCLUSIONS: Genetic subtypes identified are among the most common ones in LCA; the phenotypes are consistent with those reported previously. Both novel mutations are predicted to result in a premature translation termination. The phenotype related to the novel CRB1 mutation results in severe atrophic maculopathy.

Role of multifocal electroretinography in the diagnosis of idiopathic macular hole.

PURPOSE: To analyze the preoperative results of multifocal electroretinography (mfERG) in the fellow eyes of patients with idiopathic unilateral macular hole and to evaluate the usefulness of this method in predicting the likelihood of macular hole formation in the fellow eye. METHODS: Over a period of 5 years, 80 eyes of 40 patients (mean age, 64.9 years) with unilateral idiopathic macular hole were examined. The diagnosis of idiopathic macular hole was confirmed by optical coherence tomography (OCT). The fellow eyes were intact in all cases. All patients underwent vitreoretinal surgery. Before the surgery, both eyes of the patients were examined by mfERG. During the follow-up period, the 40 fellow eyes were also observed by OCT, and the changes in the vitreofoveal attachment were investigated. The preoperative response densities and ring ratios of mfERG were analyzed in both eyes, and discriminant analysis was used to calculate the best separator function. RESULTS: Preoperative mfERGs demonstrated significantly lower mean response densities in the central area of the 40 eyes with macular hole than in the fellow eyes. During the follow-up period, macular hole was diagnosed in 13 fellow eyes by OCT. The preoperative values of the mfERGs in these eyes were significantly lower than in the other 27 cases. The mfERG ring ratios were significantly lower in the fellow eyes in which macular holes developed than in those that remained intact. CONCLUSIONS: The analysis of ERG in the fellow eyes of patients with macular hole seems clinically useful. The lower amplitude may forecast the propensity for subsequent development of a macular hole. Patients with low central ERG amplitude and lower ring ratios in the healthy fellow eyes should have stricter follow-up.

Truncation of retinoschisin protein associated with a novel splice site mutation in the RS1 gene.

PURPOSE: To present the ocular findings of a Hungarian family with X-linked juvenile retinoschisis (XLRS) and to reveal a novel putative splice mutation leading to serious truncation of retinoschisin (RS1) protein. Our genetic results were compared to a mouse model of XLRS. METHODS: Complete ophthalmic examinations were performed on five members (two male patients, two female carriers, and one healthy fraternal male twin) of the family. The examinations included optical coherence tomography (OCT) and full-field and multifocal electroretinography (mfERG). OCT and ERG results were compared to the normative database of our laboratory. All exons and the flanking intronic regions of the RS1 gene were amplified by polymerase chain reaction and directly sequenced in all family members and in 50 male controls. RESULTS: Typical microcystic foveal changes were found on fundoscopy and OCT in two male patients. Large foveal and smaller perifoveal cysts were detected by OCT in the inner nuclear layer and another deeper retinal cleavage in the photoreceptor layer. The standard combined b-wave amplitudes and b/a amplitude ratios of full-field ERGs of the male patients were decreased compared with controls, but the typical "negative-type" ERG was not observed. The amplitudes of mfERGs were reduced in all rings but mainly in the central part of the examined retina. Implicit times were delayed across almost the whole testing field. Female carriers and the healthy fraternal twin brother were without any symptoms and had normal clinical examination results, but the implicit times of female carriers were delayed in all rings. DNA sequence analyses revealed a novel putative splice mutation (c.78+1G>C) in the splice donor site of intron 2 in RS1 of two male patients and two female carriers. Mutations were absent in the 50 control samples. CONCLUSIONS: Male patients exhibited typical bilateral foveal retinoschisis in two retinal layers and characteristic ERG changes. The inheritance of the novel putative splice mutation (c.78+1G>C) followed the classic inheritance of an X-linked recessive disease in two male patients and two female obligate carriers. There are two possible ways the c.78+1G>C splice site mutation may lead to frameshift and introduce a premature termination codon at the beginning of exon 3: after activation of the next cryptic splice site by a 10 bp insertion or after exon skipping by a 26 bp deletion. The splice site mutation in the second intron of RS1 identified in these XLRS patients is practically identical to the N-ethyl-N-nitrosourea (ENU) induced splice site mutation in the mouse model of XLRS described by the Tennessee Mouse Genome Consortium. The genetic findings of the mutant mouse model confirm and support our human results.

Optical coherence tomography of the macula in congenital achromatopsia.

PURPOSE: It is known that symptoms of congenital achromatopsia are caused by the lack of functioning cones, but there are very few published data on histologic changes in the retina in these cases. This study was conducted to examine in vivo the anatomic structure of the retina of patients with achromatopsia. METHODS: Fifteen eyes of eight patients with congenital achromatopsia and 18 eyes of nine control subjects were examined by optical coherence tomography. Radial 6-mm scans were taken of the macula. The thickness of the neuroretina was measured both automatically and manually. Measurements were taken at the foveola and at distances of 1.5 and 3 mm. Total macular volume and the retinal thickness in the nine ETDRS regions were also calculated. RESULTS: In patients with achromatopsia, statistically significant reductions were found in total macular volume and in the thickness of the central retina. Remarkable differences were found between the results obtained from different methods of measuring retinal thickness. Automated methods underestimated retinal thickness compared with manual measurements. CONCLUSIONS: The structure of the macula in achromats differs from that in normal subjects. A possible reason for the structural alteration is the qualitative and/or quantitative disorder of the cone photoreceptors, as the morphologic change is most expressed in the foveola. The automated methods are not always suitable for measuring retinal thickness in the foveola. The structural changes seen in the central retina of the patients could provide useful information for future gene therapy.

Functional assessment of the possible toxicity of indocyanine green dye in macular hole surgery.

PURPOSE: To evaluate the possible toxicity of indocyanine green (ICG) dye in macular hole surgery by comparing functional results after successful surgeries performed with and without staining. DESIGN: Prospective observational case series. METHODS: In a study conducted at our department, 30 eyes of 29 patients with idiopathic macular hole underwent pars plana vitrectomy, with peeling of the internal limiting membrane (ILM). In 21 eyes (group A), ICG staining was used to visualize the membrane; in nine eyes (group B), no dye was applied. Pre- and postoperative examinations (at three, six, 12, and 20 months) included visual acuity (VA) (Snellen chart), slit-lamp biomicroscopy, multifocal electroretinography (mfERG), and optical coherence tomography (OCT). For statistical analysis, the Mann-Whitney U test and Newman-Keuls post hoc analysis were used. RESULTS: The macular hole was closed in all patients. At 20 months, VA improvement (logarithm of minimal angle of resolution units) compared with baseline was more pronounced in group B (P < .001) than in group A (P = .022); VA was also better for group B compared directly with group A (P = .048). For mfERG, preoperative responses were subnormal. Postoperatively, responses initially decreased, but at 20 months significant improvement was seen in both groups (P < .001). When data from the groups are compared at 20 months, significantly greater mfERG improvement was found in group B in both central and perimacular areas (P < .001). CONCLUSIONS: The significantly better outcomes without staining may suggest dye toxicity. Alternative internal limiting membrane visualization substances with fewer adverse effects (trypan blue, triamcinolone) may be preferable.