Genotype-phenotype correlations of low-frequency variants in the complement system in renal disease and age-related macular degeneration

Genetic alterations in the complement system have been linked to a variety of diseases, including atypical hemolytic uremic syndrome (aHUS), C3 glomerulopathy (C3G), and age‐related macular degeneration (AMD). We performed sequence analysis of the complement genes complement factor H (CFH), complement factor I (CFI), and complement C3 (C3) in 866 aHUS/C3G and 697 AMD patients. In total, we identified 505 low‐frequency alleles, representing 121 unique variants, of which 51 are novel. CFH contained the largest number of unique low‐frequency variants (n = 64; 53%), followed by C3 (n = 32; 26%) and CFI (n = 25; 21%). A substantial number of variants were found in both patients groups (n = 48; 40%), while 41 (34%) variants were found only in aHUS/C3G and 32 (26%) variants were AMD specific. Genotype‐phenotype correlations between the disease groups identified a higher frequency of protein altering alleles in short consensus repeat 20 (SCR20) of factor H (FH), and in the serine protease domain of factor I (FI) in aHUS/C3G patients. In AMD, a higher frequency of protein‐altering alleles was observed in SCR3, SCR5, and SCR7 of FH, the SRCR domain of FI, and in the MG3 domain of C3. In conclusion, we observed a substantial overlap of variants between aHUS/C3G and AMD; however, there is a distinct clustering of variants within specific domains.

Further audiovestibular characterization of DFNB77, caused by deleterious variants in LOXHD1, and investigation into the involvement of Fuchs corneal dystrophy

This study focuses on further characterization of the audiovestibular phenotype and on genotype-phenotype correlations of DFNB77, an autosomal recessive type of hearing impairment (HI). DFNB77 is associated with disease-causing variants in LOXHD1, and is genetically and phenotypically highly heterogeneous. Heterozygous deleterious missense variants in LOXHD1 have been associated with late-onset Fuchs corneal dystrophy (FCD). However, up to now screening for FCD of heterozygous carriers in DFNB77 families has not been reported. This study describes the genotype and audiovestibular phenotype of 9 families with DFNB77. In addition, carriers within the families were screened for FCD. Fifteen pathogenic missense and truncating variants were identified, of which 12 were novel. The hearing phenotype showed high inter- and intrafamilial variation in severity and progression. There was no evidence for involvement of the vestibular system. None of the carriers showed (pre-clinical) symptoms of FCD. Our findings expand the genotypic and phenotypic spectrum of DFNB77, but a clear correlation between the type or location of the variant and the severity or progression of HI could not be established. We hypothesize that environmental factors or genetic modifiers are responsible for phenotypic differences. No association was found between heterozygous LOXHD1 variants and the occurrence of FCD in carriers.

Comparing the Effectiveness of Bevacizumab to Ranibizumab in Patients with Exudative Age-Related Macular Degeneration. The BRAMD Study

Purpose

To compare the effectiveness of bevacizumab and ranibizumab in the treatment of exudative age-related macular degeneration (AMD).

Design

Multicentre, randomized, controlled, double-masked clinical trial in 327 patients. The non-inferiority margin was 4 letters.

Patients

Patients ≥ 60 years of age with primary or recurrent sub- or juxtafoveal choroidal neovascularization (CNV) secondary to AMD with a total area of CNV < 12 disc areas and a best corrected visual acuity (BCVA) score between 20 and 78 letters on an EDTRS like chart in the study eye.

Methods

Monthly intravitreal injections with 1.25 mg bevacizumab or 0.5 mg ranibizumab were given during one year. Intention to treat with last observation carried forward analysis was performed.

Main Outcome Measures

Primary outcome was the change in BCVA in the study eye from baseline to 12 months.

Results

The mean gain in BCVA was 5.1 (±14.1) letters in the bevacizumab group (n = 161) and 6.4 (±12.2) letters in the ranibizumab group (n = 166) (p = 0.37). The lower limit of the 95% confidence interval of the difference in BCVA gain was 3.72. The response to bevacizumab was more varied; 24% of patients showed a gain of ≥15 letters, 11% a loss of ≥15 letters and 65% a gain or loss < 15 letters compared to 19%, 5% and 76% respectively for ranibizumab (p = 0.038). No significant differences in absolute CRT and CRT change (p = 0.13) or in the presence of subretinal or intraretinal fluid (p = 0.14 and 0.10, respectively) were observed. However, the presence of any fluid on SD-OCT (subretinal and/or intraretinal) differed significantly (p = 0.020), with definite fluid on SD-OCT in 45% of the patients for bevacizumab versus 31% for ranibizumab. The occurrence of serious adverse events and adverse events was similar, with 34 SAEs and 256 AEs in the bevacizumab group and 37 SAEs and 299 AEs in the ranibizumab group (p = 0.87 and p = 0.48, respectively).

Conclusions

Bevacizumab was not inferior to ranibizumab. The response to bevacizumab was more varied with higher percentages of both gainers and losers and more frequently observed retinal fluid on SD-OCT at 12 months when compared to the ranibizumab group.

Trial Registration

Trialregister.nl NTR1704

Comparing the effectiveness and costs of Bevacizumab to Ranibizumab in patients with Diabetic Macular Edema: a randomized clinical trial (the BRDME study)

BACKGROUND

The effectiveness of ranibizumab in the treatment of diabetic macular edema has been proven with large clinical trials. For bevacizumab only two clinical trials have been published and a head-to-head comparison is lacking to date. However, if proved non-inferior to ranibizumab, use of the off-label bevacizumab could reduce costs enormously without a loss in visual acuity. A cost-effectiveness study has been designed to substantiate this hypothesis.

AIM

To compare the effectiveness and costs of 1.25 mg of bevacizumab to 0.5 mg ranibizumab given as monthly intravitreal injections during 6 months in patients with diabetic macular edema. It is hypothesized that bevacizumab is non-inferior to ranibizumab regarding its effectiveness.

DESIGN

This is a randomized, controlled, double masked, clinical trial in 246 patients in seven academic trial centres in The Netherlands.

OUTCOMES

The primary outcome measure is the change in best-corrected visual acuity (BCVA) in the study eye from baseline to month 6. Secondary outcomes are the proportions of patients with a gain or loss of 15 letters or more or a BCVA of 20/40 or more at 6 months, the change in leakage on fluorescein angiography and the change in foveal thickness by optical coherence tomography at 6 months, the number of adverse events in 6 months, and the costs per quality adjusted life-year of the two treatments.

Intravenous diclofenac as prophylactic treatment for verteporfin-associated low back pain

PURPOSE

The authors report on the therapeutic effect of intravenous diclofenac on verteporfin associated low back pain (LBP), which is the most frequent adverse effect of photodynamic therapy (PDT) for macular degeneration.

METHODS

The authors studied 818 patients who received PDT with verteporfin for choroidal neovascularization. Systemic blood pressures were recorded in all study participants half an hour before PDT treatment. All patients who experienced LBP during verteporfin infusion were asked to grade their pain as mild (1), moderate (2), severe (3), or unbearable (4).

RESULTS

Thirty-three patients had LBP during their first verteporfin infusion. Of these, 11 subjects (1.34% of all) reported increased pain scores (level 2 to 4) and received intravenous diclofenac ahead of their next PDT. Patients with LBP during verteporfin infusion had significantly higher systolic blood pressures than uncomplicated cases (180 mmHg vs 155 mmHg, p=0.01). Treatment with intravenous diclofenac short before PDT significantly reduced the patients' mean pain score by 1.8 levels (p=0.0001).

CONCLUSIONS

In this study, intravenous application of diclofenac short before verteporfin infusion effectively prevented verteporfin associated LBP in patients with systemic hypertension.

[The Dutch version of the Radner Reading Chart for assessing vision function]

A chart for measuring visual acuity is a better functional test than the routine distance visual acuity testing with single optotypes. The characteristics of a good reading chart are: logarithmically diminishing print size, simultaneous measurement of reading acuity and reading speed, and the calculation of one score for reading acuity corrected for the number of reading errors. The original German-language Radner Reading Chart meets all these requirements, and above all emphasizes the principle of 'sentence optotypes' i.e. highly standardized sentences, because sentence complexity also influences reading performance. Sentence optotypes were created in the Dutch language and tested according to Radner's strict principles. The most equally matched sentence optotypes in terms of reading speed and number of reading errors were selected for the introduction and printing of the first Dutch version of the Radner Reading Chart. The Dutch Radner Reading Chart is precise and practical and therefore useful for research and daily practice.

Ocular syphilis acquired through oral sex in two HIV-infected patients

Two cases of ocular syphilis are described in HIV-infected individuals after unprotected oral sex. The primary syphilitic lesion remained unnoticed and lues was therefore only diagnosed after visual symptoms developed.

Genotyping microarray (gene chip) for the ABCR (ABCA4) gene

Genetic variation in the ABCR (ABCA4) gene has been associated with five distinct retinal phenotypes, including Stargardt disease/fundus flavimaculatus (STGD/FFM), cone-rod dystrophy (CRD), and age-related macular degeneration (AMD). Comparative genetic analyses of ABCR variation and diagnostics have been complicated by substantial allelic heterogeneity and by differences in screening methods. To overcome these limitations, we designed a genotyping microarray (gene chip) for ABCR that includes all approximately 400 disease-associated and other variants currently described, enabling simultaneous detection of all known ABCR variants. The ABCR genotyping microarray (the ABCR400 chip) was constructed by the arrayed primer extension (APEX) technology. Each sequence change in ABCR was included on the chip by synthesis and application of sequence-specific oligonucleotides. We validated the chip by screening 136 confirmed STGD patients and 96 healthy controls, each of whom we had analyzed previously by single strand conformation polymorphism (SSCP) technology and/or heteroduplex analysis. The microarray was >98% effective in determining the existing genetic variation and was comparable to direct sequencing in that it yielded many sequence changes undetected by SSCP. In STGD patient cohorts, the efficiency of the array to detect disease-associated alleles was between 54% and 78%, depending on the ethnic composition and degree of clinical and molecular characterization of a cohort. In addition, chip analysis suggested a high carrier frequency (up to 1:10) of ABCR variants in the general population. The ABCR genotyping microarray is a robust, cost-effective, and comprehensive screening tool for variation in one gene in which mutations are responsible for a substantial fraction of retinal disease. The ABCR chip is a prototype for the next generation of screening and diagnostic tools in ophthalmic genetics, bridging clinical and scientific research.

The expanding roles of ABCA4 and CRB1 in inherited blindness

Mutations in the ABCA4 gene cause Stargardt disease (STGD), most cases with autosomal recessive (ar) cone-rod dystrophy (CRD), and some cases with atypical ar retinitis pigmentosa (arRP). We found compound heterozygous ABCA4 mutations in two unrelated patients with STGD and homozygous splice site mutations in their 2nd and 4th degree cousins with RP. Some ABCA4 mutations display strong founder effects. In Dutch and German STGD patients, the 768G > T mutation is present in 8% and 0.6% of ABCA4 alleles respectively. Vice versa, the complex L541P;A1038V allele is found in 70% of ABCA4 alleles in German STGD patients but absent in Dutch patients. As approximately 70% of ABCA4 mutations are known, a microarray-based analysis of known ABCA4 gene variants allows routine DNA diagnostics in Caucasian patients. Mutations in the CRB1 gene underlie RP12, some cases with classic arRP, 55% of cases with RP and Coats-like exudative vasculopathy, and 13% of patients with Leber congenital amaurosis (LCA), rendering CRB1 a significant cause of autosomal recessive retinal dystrophy. Different combinations of mutations in ABCA4 or CRB1 can be correlated with disease severity, suggesting that small increments of protein activities in patients might have significant therapeutic effects. Mouse and Drosophila studies strongly suggest that both patient groups might benefit from reduced light exposure and therefore should be detected as early as possible using molecular techniques.

[From gene to disease: from the ABCA4 gene to Stargardt disease, cone-rod dystrophy and retinitis pigmentosa]

Autosomal recessive Stargardt disease is caused by mutations in the ABCA4 gene. Mutations in ABCA4 are also found in two-thirds of cases with autosomal recessive cone-rod dystrophy, and a small fraction of patients with autosomal recessive retinitis pigmentosa. Patients with autosomal recessive retinitis pigmentosa, the most severe of these three phenotypes, invariably carry ABCA4 inactivating mutations; patients with autosomal recessive cone-rod dystrophy and Stargardt disease carry combinations of mutations that do not completely inactivate the retina specific 'ATP-binding cassette transporter' (ABCR) protein. DNA diagnostics is complicated by the high allelic heterogeneity and the uncertainty as to whether some ABCA4 variants are pathological. Nevertheless, ABCA4 mutation analysis is particularly important for patients with cone-rod dystrophy to confirm the autosomal recessive mode of inheritance.

Neovascular age-related macular degeneration and its relationship to antioxidant intake

PURPOSE

Experimental and epidemiological studies suggest that low antioxidant intake may be associated with the occurrence of neovascular age-related macular degeneration (AMD).

METHODS

We investigated this hypothesis further with a case-control study involving 72 case and 66 control patients attending the Ophthalmology Department of the University Hospital in Nijmegen. Data were collected by interview on antioxidant intake (i.e. in fruit and vegetables), cigarette smoking, sunlight exposure and familial predisposition. Antioxidant intake was calculated according to the method described in the Framingham Eye Study. Logistic regression analysis was used to estimate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

The prevalence rate of AMD in patients with low antioxidant intake and low lutein intake (dichotomized at the median value) was about twice as high as that in patients with high intake: OR = 1.7, 95% CI (0.8-3.7), and OR = 2.4, 95% CI (1.1-5.1). Further specification of intake data into quartiles of antioxidant intake and lutein/zeaxanthine intake showed a clear dose-response relationship.

CONCLUSION

The effect of dietary antioxidants upon macular health warrants preventive studies.

Clinical characterization, linkage analysis, and PRPC8 mutation analysis of a family with autosomal dominant retinitis pigmentosa type 13 (RP13)

A Dutch family with autosomal dominant retinitis pigmentosa (adRP) displayed a phenotype characterized by an early age of onset, a diffuse loss of rod and cone sensitivity, and constricted visual fields (type I). One male showed a mild progression of the disease. Linkage analysis showed cosegregation of the genetic defect with markers from chromosome 17p13.1-p13.3, a region overlapping the RP13 locus. The critical interval of the RP locus as defined in this family was flanked by D17S926 and D17S786, with a maximal lod score of 4.2 (theta = 0.00) for marker D17S1529. Soon after the mapping of the underlying defect to the 17p13 region, a missense mutation (6970G>A; R2310K) was identified in exon 42 of the splicing factor gene PRPC8 in one patient of this family. Diagnostic restriction enzyme digestion of exon 42 amplified from genomic DNA of all family members revealed that the R2310K mutation segregated fully with the disease. The type I phenotype observed in this family is similar to that described for three other RP13 families with mutations in PRPC8.

Mutations in the pre-mRNA splicing factor gene PRPC8 in autosomal dominant retinitis pigmentosa (RP13)

Retinitis pigmentosa (RP) is a genetically heterogeneous disorder characterized by progressive degeneration of the peripheral retina leading to night blindness and loss of visual fields. With an incidence of approximately 1 in 4000, RP can be inherited in X-linked, autosomal dominant or autosomal recessive modes. The RP13 locus for autosomal dominant RP (adRP) was placed on chromosome 17p13.3 by linkage mapping in a large South African adRP family. Using a positional cloning and candidate gene strategy, we have identified seven different missense mutations in the splicing factor gene PRPC8 in adRP families. Three of the mutations cosegregate within three RP13 linked families including the original large South African pedigree, and four additional mutations have been identified in other unrelated adRP families. The seven mutations are clustered within a 14 codon stretch within the last exon of this large 7 kb transcript. The altered amino acid residues at the C-terminus exhibit a high degree of conservation across species as diverse as humans, Arabidopsis and trypanosome, suggesting that some functional significance is associated with this part of the protein. These mutations in this ubiquitous and highly conserved splicing factor offer compelling evidence for a novel pathway to retinal degeneration.

Leber congenital amaurosis and retinitis pigmentosa with Coats-like exudative vasculopathy are associated with mutations in the crumbs homologue 1 (CRB1) gene

Mutations in the crumbs homologue 1 (CRB1) gene cause a specific form of retinitis pigmentosa (RP) that is designated "RP12" and is characterized by a preserved para-arteriolar retinal pigment epithelium (PPRPE) and by severe loss of vision at age <20 years. Because of the early onset of disease in patients who have RP with PPRPE, we considered CRB1 to be a good candidate gene for Leber congenital amaurosis (LCA). Mutations were detected in 7 (13%) of 52 patients with LCA from the Netherlands, Germany, and the United States. In addition, CRB1 mutations were detected in five of nine patients who had RP with Coats-like exudative vasculopathy, a relatively rare complication of RP that may progress to partial or total retinal detachment. Given that four of five patients had developed the complication in one eye and that not all siblings with RP have the complication, CRB1 mutations should be considered an important risk factor for the Coats-like reaction, although its development may require additional genetic or environmental factors. Although no clear-cut genotype-phenotype correlation could be established, patients with LCA, which is the most severe retinal dystrophy, carry null alleles more frequently than do patients with RP. Our findings suggest that CRB1 mutations are a frequent cause of LCA and are strongly associated with the development of Coats-like exudative vasculopathy in patients with RP.

Mutations in the ABCA4 (ABCR) gene are the major cause of autosomal recessive cone-rod dystrophy

The photoreceptor cell-specific ATP-binding cassette transporter gene (ABCA4; previously denoted "ABCR") is mutated, in most patients, with autosomal recessive (AR) Stargardt disease (STGD1) or fundus flavimaculatus (FFM). In addition, a few cases with AR retinitis pigmentosa (RP) and AR cone-rod dystrophy (CRD) have been found to have ABCA4 mutations. To evaluate the importance of the ABCA4 gene as a cause of AR CRD, we selected 5 patients with AR CRD and 15 patients from Germany and The Netherlands with isolated CRD. Single-strand conformation-polymorphism analysis and sequencing revealed 19 ABCA4 mutations in 13 (65%) of 20 patients. In six patients, mutations were identified in both ABCA4 alleles; in seven patients, mutations were detected in one allele. One complex ABCA4 allele (L541P;A1038V) was found exclusively in German patients with CRD; one patient carried this complex allele homozygously, and five others were compound heterozygous. These findings suggest that mutations in the ABCA4 gene are the major cause of AR CRD. A primary role of the ABCA4 gene in STGD1/FFM and AR CRD, together with the gene's involvement in an as-yet-unknown proportion of cases with AR RP, strengthens the idea that mutations in the ABCA4 gene could be the most frequent cause of inherited retinal dystrophy in humans.

Relationship between anticoagulant medication and massive intraocular hemorrhage in age-related macular degeneration

BACKGROUND

A massive intraocular hemorrhage in the course of age-related macular degeneration (AMD) is a devastating event. We set out to determine the role of anticoagulant therapy prescribed for vascular or cardiac indications in the development of a massive hemorrhage.

METHODS

A retrospective case-controlled study was conducted of 50 cases of age-related macular degeneration complicated by massive subretinal and vitreous hemorrhage. The control group consisted of 50 cases of AMD with small subretinal hemorrhage.

RESULTS

There was a significant difference in the use of anticoagulant medication (warfarin sodium) between the groups. The difference in the use of antiplatelet medication (aspirin) between the groups was not significant. A patient with a massive intraocular hemorrhage and AMD is 11.6 times more likely to use anticoagulant medication. It appeared that more than 50% of the patients in the massive hemorrhage group were allowed to stop the anticoagulant medication.

CONCLUSION

Anticoagulant medication poses a significant risk in the development of a massive intraocular hemorrhage in patients with exudative AMD. Antiplatelet medication poses a less significant risk. Physicians prescribing anticoagulant medication should be informed about the macular status of the patient. the In case of neovascular AMD, anticoagulant medication should be prescribed only for absolute systemic indications.

Mutations in a human homologue of Drosophila crumbs cause retinitis pigmentosa (RP12)

Retinitis pigmentosa (RP) comprises a clinically and genetically heterogeneous group of diseases that afflicts approximately 1.5 million people worldwide. Affected individuals suffer from a progressive degeneration of the photoreceptors, eventually resulting in severe visual impairment. To isolate candidate genes for chorioretinal diseases, we cloned cDNAs specifically or preferentially expressed in the human retina and the retinal pigment epithelium (RPE) through a novel suppression subtractive hybridization (SSH) method. One of these cDNAs (RET3C11) mapped to chromosome 1q31-q32.1, a region harbouring a gene involved in a severe form of autosomal recessive RP characterized by a typical preservation of the para-arteriolar RPE (RP12; ref. 3). The full-length cDNA encodes an extracellular protein with 19 EGF-like domains, 3 laminin A G-like domains and a C-type lectin domain. This protein is homologous to the Drosophila melanogaster protein crumbs (CRB), and denoted CRB1 (crumbs homologue 1). In ten unrelated RP patients with preserved para-arteriolar RPE, we identified a homozygous AluY insertion disrupting the ORF, five homozygous missense mutations and four compound heterozygous mutations in CRB1. The similarity to CRB suggests a role for CRB1 in cell-cell interaction and possibly in the maintenance of cell polarity in the retina. The distinct RPE abnormalities observed in RP12 patients suggest that CRB1 mutations trigger a novel mechanism of photoreceptor degeneration.

Phenotypic variations in a family with retinal dystrophy as result of different mutations in the ABCR gene

AIMS

To describe two phenotypic variations of autosomal recessive retinal dystrophy occurring in a consanguineous family in a pseudodominant pattern, resulting from mutations in the ATP binding cassette transporter (ABCR) gene.

METHODS

Patients of this family underwent an extensive ophthalmic evaluation, including fundus photography, fluorescein angiography, and electroretinography (ERG). Genetic analysis comprised sequence analysis of the retina specific ABCR gene.

RESULTS

Five patients presented with decreased visual acuity in the second decade, central chorioretinal atrophy associated with a central scotoma, and severely decreased photopic and scotopic ERG responses. This clinical picture, which in our opinion resembles a cone-rod dystrophy (CRD), was associated with compound heterozygosity for IVS30+ 1g -->t and IVS40+5g-->a mutations in the ABCR gene. The four remaining patients presented with night blindness in the first decade because of a retinitis pigmentosa-like (RP-like) dystrophy. In addition to a pale "waxy" optic disc, attenuated retinal vessels and bone spicule deposits, a widespread chorioretinal atrophy was observed. The scotopic ERG was extinguished and the photopic ERG was severely diminished. Genetic analysis revealed a homozygous 5' splice mutation IVS30+1g -->t in the ABCR gene.

CONCLUSION

Mutations in the ABCR gene can cause clinical pictures resembling autosomal recessive RP and autosomal recessive CRD.

Isolation and mapping of novel candidate genes for retinal disorders using suppression subtractive hybridization

We have constructed human cDNA libraries enriched for retina- and retinal pigment epithelium (RPE)/choroid-specific cDNAs through suppression subtractive hybridization. The sequence of 314 cDNAs from the retina enriched library and 126 cDNAs from the RPE/choroid enriched library was analyzed. Based on the absence of a database match, 25% of the retina cDNA clones and 16% of the RPE/choroid cDNA clones are novel cDNAs. The expression profiles of 86 retina and 21 RPE/choroid cDNAs were determined by a semiquantitative reverse transcription polymerase chain reaction technique. Thirty-three cDNAs were expressed exclusively or most prominently in retina or RPE/choroid. These cDNAs were mapped in the human genome by radiation hybrid mapping. Eleven cDNAs colocalized with loci involved in retinal disorders. One cDNA mapped in a 1.5-megabase critical region for autosomal recessive retinitis pigmentosa (RP12). Another cDNA was assigned to the 7.7-cM RP17 linkage interval. Seven cDNAs colocalized with four loci involved in Bardet-Biedl syndrome.

The 2588G-->C mutation in the ABCR gene is a mild frequent founder mutation in the Western European population and allows the classification of ABCR mutations in patients with Stargardt disease

In 40 western European patients with Stargardt disease (STGD), we found 19 novel mutations in the retina-specific ATP-binding cassette transporter (ABCR) gene, illustrating STGD's high allelic heterogeneity. One mutation, 2588G-->C, identified in 15 (37.5%) patients, shows linkage disequilibrium with a rare polymorphism (2828G-->A) in exon 19, suggesting a founder effect. The guanine at position 2588 is part of the 3' splice site of exon 17. Analysis of the lymphoblastoid cell mRNA of two STGD patients with the 2588G-->C mutation shows that the resulting mutant ABCR proteins either lack Gly863 or contain the missense mutation Gly863Ala. We hypothesize that the 2588G-->C alteration is a mild mutation that causes STGD only in combination with a severe ABCR mutation. This is supported in that the accompanying ABCR mutations in at least five of eight STGD patients are null (severe) and that a combination of two mild mutations has not been observed among 68 STGD patients. The 2588G-->C mutation is present in 1 of every 35 western Europeans, a rate higher than that of the most frequent severe autosomal recessive mutation, the cystic fibrosis conductance regulator gene mutation DeltaPhe508. Given an STGD incidence of 1/10,000, homozygosity for the 2588G-->C mutation or compound heterozygosity for this and other mild ABCR mutations probably does not result in an STGD phenotype.

Refined mapping of the gene for autosomal dominant retinitis pigmentosa (RP17) on chromosome 17q22

Linkage analysis was performed on a large Dutch family with autosomal dominant retinitis pigmentosa. Linkage was found to the RP17 locus on chromosome 17q22, which was previously described in two South African families by Bardien et al. (1995, 1997). Assuming that the disease phenotypes in these families are caused by the same gene, the RP17 critical region is refined to a 7.7-cM interval between markers D17S1607 and D17S948. Two positional candidate genes, the retina-specific amine oxidase (RAO) gene (AOC2) and the cone transducin gamma gene (GNGT2), were excluded.

Analysis of immunoregulatory cytokines in ocular fluid samples from patients with uveitis

PURPOSE

To investigate the T-helper cell cytokine profiles in two well-defined clinical uveitis entities caused by an infectious mechanism.

METHODS

Cytokines (interleukin [IL]-2, IL-4, IL-6, IL-10, and interferon [IFN]-gamma) were measured in ocular fluid samples obtained from patients with herpes simplex- or varicella-zoster virus-induced acute retinal necrosis (ARN; n = 17) and toxoplasma chorioretinitis (n = 27) using enzyme-linked immunosorbent assay techniques. The data were compared with data for 51 control samples taken during cataract surgery (n = 10), vitrectomy in diabetic retinopathy (n = 10), eye bank eyes (n = 10) and with samples from patients with "autoimmune" uveitis (n = 21).

RESULTS

Interleukin-6 was detected in 44 of 51 control samples and 43 of 44 eyes of patients with uveitis. The highest levels in the control samples were detected in 9 of 10 vitreous samples from patients with diabetic retinopathy (mean, 648 pg/ml). In 8 of 10 samples taken from patients during cataract surgery and in 7 of 10 eye bank eyes the amount of IL-6 was significantly lower (mean, 10 pg/ml and 136 pg/ml, respectively). Interleukin-6 levels in patients with ARN (mean, 1436 pg/ml) were significantly higher than in those with toxoplasma chorioretinitis (mean, 272 pg/ml). Interleukin-2 was detected in one of the samples from patients with toxoplasma chorioretinitis (1105 pg/ml) and in three samples from the control subjects suffering from Fuchs' heterochromic anterior uveitis (mean, 752 pg/ml). No IL-4 (<2 pg/ml) was detected either in patient or control samples. Interferon-gamma could be detected in 7 of 17 ARN patients (range, 277-3483 pg/ml), in 13 of 27 samples from patients with toxoplasma chorioretinitis (range, 12-250 pg/ml), and in 1 of 21 of the samples from control subjects with uveitis (31 pg/ml) but was absent in nonuveitic control samples. Interleukin-10 was detected in 10 of 17 ARN patients (range, 29-3927 pg/ml), in 13 of 27 samples from patients with toxoplasma chorioretinitis (range, 4-67 pg/ml), and in only 3 of 51 control samples (6 pg/ml, 16 pg/ml, and 20 pg/ml).

CONCLUSIONS

Various immunoregulatory cytokines (IL-6, IL-10, and IFN-gamma) were detected in ocular fluid samples from patients with uveitis. A separate role for either a T-helper type 1 or T-helper type 2 response in the pathogenesis of clinical uveitis could not be proven.

ABCR unites what ophthalmologists divide(s)

Over the last years, the molecular causes of monogenic chorioretinal diseases have been elucidated at an increasing pace. In contrast, only recently have genetic factors been found that contribute to multifactorial eye disorders such as age-related macular degeneration (AMD). Mutations in the retina-specific ATP-binding cassette transporter gene (ABCR) cause recessive Stargardt's disease (STGD) and fundus flavimaculatus (FFM), and were also found in 16% of patients with AMD. In addition, ABCR mutations were identified in families with recessive retinitis pigmentosa (RP), cone dystrophy (COD), and cone-rod dystrophy (CRD). In this review, we summarize these findings and propose a model which provides a framework to explain the observed genotypes and phenotypes. We hypothesize that most ABCR mutations can be classified in different classes of severity, and that, depending on the remaining total activity of ABCR, the phenotype can range from AMD at the mild end to RP at the severe end of the spectrum. This model allows us to make several predictions on the type and/or severity of ABCR mutations that are present in patients with AMD, STGD/FFM, COD, CRD, and RP.

Cytomegalovirus (CMV) strain differences between the eye and blood in AIDS patients with CMV retinitis

OBJECTIVE

To investigate possible differences in cytomegalovirus (CMV) strain distribution between the eye and blood in AIDS patients with CMV retinitis.

METHODS

CMV DNA sequences from aqueous humour and peripheral blood leukocytes (PBL), obtained from 13 AIDS patients with CMV retinitis, were compared. DNA was isolated and the CMV IE-1 sequence (part of the immediate early-1 gene) and the a-sequence (located in the a-region) were amplified by polymerase chain reaction (PCR). The PCR products of the a-sequence were analysed by Southern blotting for amplified fragment-length polymorphisms. The level of divergence between the a-sequences of aqueous humour- and PBL-derived CMV was studied in two patients by cloning these sequences followed by sequence analysis.

RESULTS

CMV DNA could be detected in all aqueous humour samples and in 10 out of 13 paired blood samples. In the 10 patients, with CMV DNA detectable in both aqueous humour and PBL, seven cases showed differences between the amplified products of both compartments. Sequence analysis in two patients revealed that the aqueous humour and PBL of the same patient can harbour both identical, similar and highly divergent CMV a-sequences.

CONCLUSION

These results indicate that despite the haematogenous spread of CMV, the eye, being a relatively shielded organ, may contain CMV strains different from those found in the blood.

A randomized controlled clinical trial on the efficacy of radiation therapy in the control of subfoveal choroidal neovascularization in age-related macular degeneration: radiation versus observation

BACKGROUND

The results of several pilot studies concerning radiation therapy for age-related subfoveal choroidal neovascularization (CNV) have been published recently. Although positive treatment results have been described, it is not known whether this therapy alters the natural course of eyes with neovascular age-related macular degeneration (AMD). A randomized controlled clinical trial was conducted in which radiation therapy was compared with observation in patients with subfoveal neovascular AMD.

METHODS

Seventy-four patients with a recent drop in central vision due to subfoveal age-related CNV were randomized to either radiation treatment or observation. Patients with either classic, occult or mixed type CNV were included. Eyes in the treatment group received a radiation dose of 24 Gy in four fractions of 6 Gy. Evaluation of data concerning visual acuity (VA) and fluorescein angiography occurred at 3, 6 and 12 months after inclusion.

RESULTS

At 12 months of follow-up 52.2% of the observation group versus 32.0% of the irradiation group had lost 3 or more lines of VA (P = 0.03, log rank test). More severe visual decline, 6 lines or more, was observed in 40.9% of the observation versus 8.8% in the irradiation group (P = 0.002 using log rank test). At 12 months 39.6% of the observation group and 20.0% of the treatment group had VA of less than 0.1 (P = 0.08, log rank test). The size of the CNV membrane doubled in 25.2% of eyes in the observation group versus 20.0% in the treatment group at least 12 months (P = 0.5, log rank test). No side effects were observed.

CONCLUSION

Preservation of VA was significantly better in the treatment group compared with the control group at 12 months. Nevertheless we noted a drop in central vision of 3 or more lines in a substantial proportion of the treatment group. Radiation therapy does not prevent visual loss in all patients with age-related subfoveal CNV, and whether the treatment benefit at 12 months will persist has to be awaited.

Increased presence of Epstein-Barr virus DNA in ocular fluid samples from HIV negative immunocompromised patients with uveitis

AIMS

To investigate whether routine testing for Epstein-Barr virus (EBV) is necessary in the examination of a patient with uveitis.

METHODS

Intraocular EBV DNA was determined in 183 ocular fluid samples taken from patients with AIDS and uveitis, HIV negative immunocompromised uveitis, acute retinal necrosis, toxoplasma chorioretinitis, intraocular lymphoma, anterior uveitis, and miscellaneous uveitis of unknown cause. In 82 samples from this group of patients paired serum/ocular fluid analysis was performed to detect local antibody production against EBV. Controls (n = 46) included ocular fluid samples taken during surgery for diabetic retinopathy, macular pucker, or cataract.

RESULTS

Serum antibody titres to EBV capsid antigen proved to be significantly increased in HIV negative immunocompromised patients with uveitis (p < 0.01) compared with controls. Local antibody production revealed only three positive cases out of 82 patients tested, two results were borderline positive and one patient had uveitis caused by VZV. EBV DNA was detected in three out of 46 control ocular fluid samples. In the different uveitis groups EBV DNA was noted, but was not significantly higher than in the controls, except in six out of 11 HIV negative immunocompromised patients (p = 0.0008). In four out of these six cases another infectious agent (VZV, HSV, CMV, or Toxoplasma gondii) had previously been identified as the cause of the uveitis.

CONCLUSIONS

When comparing various groups of uveitis patients, EBV DNA was found more often in HIV negative immunocompromised patients with uveitis. Testing for EBV does not have to be included in the routine management of patients with uveitis, since indications for an important role of this virus were not found in the pathogenesis of intraocular inflammation.

Autosomal recessive retinitis pigmentosa and cone-rod dystrophy caused by splice site mutations in the Stargardt's disease gene ABCR

Ophthalmological and molecular genetic studies were performed in a consanguineous family with individuals showing either retinitis pigmentosa (RP) or cone-rod dystrophy (CRD). Assuming pseudodominant (recessive) inheritance of allelic defects, linkage analysis positioned the causal gene at 1p21-p13 (lod score 4.22), a genomic segment known to harbor the ABCR gene involved in Stargardt's disease (STGD) and age-related macular degeneration (AMD). We completed the exon-intron structure of the ABCR gene and detected a severe homozygous 5[prime] splice site mutation, IVS30+1G->T, in the four RP patients. The five CRD patients in this family are compound heterozygotes for the IVS30+1G->T mutation and a 5[prime] splice site mutation in intron 40 (IVS40+5G->A). Both splice site mutations were found heterozygously in two unrelated STGD patients, but not in 100 control individuals. In these patients the second mutation was either a missense mutation or unknown. Since thus far no STGD patients have been reported to carry two ABCR null alleles and taking into account that the RP phenotype is more severe than the STGD phenotype, we hypothesize that the intron 30 splice site mutation represents a true null allele. Since the intron 30 mutation is found heterozygously in the CRD patients, the IVS40+5G->A mutation probably renders the exon 40 5[prime] splice site partially functional. These results show that mutations in the ABCR gene not only result in STGD and AMD, but can also cause autosomal recessive RP and CRD. Since the heterozygote frequency for ABCR mutations is estimated at 0.02, mutations in ABCR might be an important cause of autosomal recessive and sporadic forms of RP and CRD.

Complete exon-intron structure of the retina-specific ATP binding transporter gene (ABCR) allows the identification of novel mutations underlying Stargardt disease

Stargardt disease, an autosomal recessive macular dystrophy of childhood, leading to severe visual impairment, is caused by mutations in the retina-specific ATP binding transporter gene (ABCR). Previously, the ABCR cDNA and part of the exon-intron structure were described. We have determined the complete ABCR exon-intron structure by exon-exon PCR. The ABCR gene encompasses 50 exons, 29 of which are first described here with their corresponding intron-exon boundaries. The discovery of a splicing mutation (571: 2A-->G) and missense mutations in the newly identified exons (R18W, R212C) gives additional support to the broad allelic heterogeneity of Stargardt disease.

[Vision rehabilitation of patients with old-age macular degeneration]

Age-related degeneration of the macula retinae occurs in two forms: the serious form with invasion of blood vessels and leakage, and the atrophic form. Both forms ultimately lead to a central scotoma. The prevalence of the terminal stage of age-related macular degeneration varies from 1% in the age group 65-74 years to 11% in those 85 years or over. A total of 58,500 persons in the Netherlands have age-related macular degeneration and an estimated 22,000 persons depend on visual or optic aids. Aids for close vision are good illumination, magnification (reading glasses, magnifying glasses, telescopic lenses, television reading lenses (with possibility of changing contrast), large-letter books, playing cards with large symbols) and auditory aids. Aids for distant vision reduce troublesome light (sunglasses, filter) or enlarge the image (telescopic aids). Future new aids derive from modern computer technology (personal computer, integrated braille reader and speech synthesizer) or are based on opto-electronic image processing and presentation (mini-cameras with mini-VDUs in a sort of helmet). Effective use of aids depends on attention for the patient's desires and possibilities and on counselling in handling aids. Ophthalmological checkups remain useful for the prevention and (or) treatment of accessory disorders.

Central areolar choroidal dystrophy and slowly progressive sensorineural hearing loss

Central areolar choroidal dystrophy (CACD) is a rare hereditary disorder leading to a central scotoma in middle-aged patients. Two cases of CACD in association with perceptive hearing loss are discussed. A 62-year-old male and a 51-year-old female patient complained of visual deterioration and subsequent hearing loss over several years. In addition to routine ophthalmic and otorhinolaryngological examination both patients underwent fluorescein angiography, (electro)physiological examination and audiometry examination. A demarcated area of atrophy of pigment epithelium and choriocapillaris was found in both patients. A slowly progressive sensorineural hearing loss after adolescence was found in both patients. The hearing deteriorated to such a level at middle age that hearing aids were necessary. These two cases show that CACD may be associated with perceptive hearing loss.

Genetic fine mapping of the gene for recessive Stargardt disease

Stargardt disease (STGD) is one of the most frequent causes of macular degeneration in childhood. Linkage analysis in families with recessive STGD has recently shown genetic homogeneity and a location of the underlying gene at 1p22-p21 in a 4-cM interval. Haplotype analysis in seven Dutch STGD families with 11 highly polymorphic markers spanning the critical region has enabled us to refine the location of the underlying gene to a 2-cM region flanked by the loci D1S406 and D1S236. We have identified one 45-year-old nonpenetrant individual who carries two disease alleles. In another family, an affected individual inherited the paternal but not the maternal disease chromosome, suggesting genetic heterogeneity or a different mechanism leading to the disease in this family.

Autosomal dominant central areolar choroidal dystrophy caused by a mutation in codon 142 in the peripherin/RDS gene

PURPOSE

Because several macular dystrophies are caused by mutations in the peripherin/RDS gene, we examined autosomal dominant and sporadic cases of central areolar choroidal dystrophy for mutations in the peripherin/RDS gene.

METHODS

DNA sequence analysis of the peripherin/RDS gene was performed in four sporadic cases and in ten affected and nine unaffected individuals from seven families with autosomal dominant central areolar choroidal dystrophy.

RESULTS

An Arg-142-Trp mutation in the peripherin/RDS gene was found in ten affected family members in seven families. Among these, a 69-year-old man with the Arg-142-Trp mutation, who was unaffected six years before blood sample analysis, showed a parafoveal area of chorioretinal atrophy. The 65-year-old sister of this family had the Arg-142-Trp mutation with no macular abnormalities, but she might still develop central areolar choroidal dystrophy at an older age. No mutation was found in the four sporadic cases.

CONCLUSION

Autosomal dominant central areolar choroidal dystrophy, studied in seven families, is caused by an Arg-142-Trp mutation in the peripherin/RDS gene.

Eccentric viewing spectacles in everyday life, for the optimum use of residual functional retinal areas, in patients with age-related macular degeneration

Most patients with end-stage age-related macular degeneration (ARMD) depend on their eccentric viewing for distance and near vision. The purpose of this study was to evaluate the subjective effects of eccentric viewing spectacles (EVS) in order to achieve the use of perimacular regions in primary gaze position.

METHOD

We fitted EVS on patients with a central scotoma secondary to end-stage ARMD. After determining the preferred retinal locus, high power prism glasses were adjusted to this area. After a follow-up period of at least 3 months, patients filled in a questionnaire concerning their perception of positive or negative effects.

RESULTS

Twenty-three of 38 patients considered the fitted EVS to be an improvement.

CONCLUSION

EVS may be helpful for the rehabilitation of patients with a central scotoma resulting from ARMD.

The development of central areolar choroidal dystrophy

BACKGROUND

Central areolar choroidal dystrophy (CACD) is a hereditary macular disorder of which the development is poorly understood.

METHODS

One hundred and eight members of seven families with CACD underwent ophthalmological examination. If macular alterations were found or suspected, the patients underwent fluorescein angiography, electroretinography (ERG), electrooculography (EOG) and tests of colour vision and visual field. CACD was divided into four stages: I, slight parafoveal changes of the pigment epithelium (RPE); II, RPE mottling encircling the fovea; III, additional atrophy of the choriocapillaris without central involvement; IV, as stage III with central involvement.

RESULTS

In 60 eyes of 30 patients, 8 with stage I, 12 with stage II, 18 with stage III and 22 with stage IV CACD were found. The photopic ERG was subnormal in about half of the cases with stage II-IV. Colour vision tests revealed diminished red sensitivity and pseudoprotanomaly in stages I and II and combined red-green and blue-yellow defect in stages III and IV. Parafoveal reduced sensitivity (stages I and II) and parafoveal and foveal reduced sensitivity (stages III and IV) were found in the visual field tests.

CONCLUSION

We describe and expand the stages of development of CACD. Early recognition of patients may have a great influence on their subsequent life.

Visual acuity and scar size in eyes with age-related subfoveal choroidal neovascular lesions, 30 months after radiation therapy

PURPOSE

In a study to determine the effectiveness of ionizing radiation on the deterioration of visual acuity (VA) due to choroidal neovascularisation (CNV) the affected eyes of 10 patients were treated with a total dose of 24 Gy (6 Gy fractions). A special lens-sparing technique was used to avoid cataract development. During 30 months of follow-up the visual acuity (VA) and scar size (SS) of the treated eyes and fellow eyes of all 10 patients were evaluated.

RESULTS

After 30 months of follow-up 5 eyes showed a stable VA and fluorescein angiogram (FA) appearance. Concerning 4 out of 5 eyes with progressive disease, the 4 eyes treated with radiation therapy had better VA and smaller SS as compared with the untreated fellow eyes with exudative AMD.

CONCLUSIONS

The results suggest that 24 Gy either stabilizes or delays the deleterious effects of CNV on the visual acuity. Until now no late side effects have been observed.

Pigmentary irregularities and optic disc edema after heart transplantation

OBJECTIVES

To determine the prevalence of chorioretinal lesions and optic disc edema after heart transplantation and to study potential associations.

DESIGN AND PATIENTS

One hundred one patients who had undergone heart transplantation at one institution and 19 patients prior to heart transplantation underwent ophthalmological examination, including fundus photography. The prevalence of fundus lesions was then compared between the two groups.

MAIN OUTCOME MEASURE

With a standardized protocol, the presence of optic disc edema, chorioretinal hyperpigmentation and depigmentation, retinal hemorrhages, cotton-wool lesions, and arteriovenous nicking was graded on color transparencies.

RESULTS

The prevalence of optic disc edema and hypopigmentations was significantly higher among the transplant recipients than among the patients prior to heart transplantation (31% vs 5%, P = .01, and 55% vs 11%, P < .001, respectively). Hyperpigmentation was only present in patients after transplantation (15% vs 0%, P = .06). Heart transplant recipients showed an increased risk of hyperpigmentations after 2.5 years. Acute rejection episodes were not associated with posterior pole lesions.

CONCLUSION

Common posterior pole lesions after heart transplantation are optic disc edema and pigmentary changes. Although visual acuity does not seem severely impaired, further longitudinal study is necessary to evaluate the long-term significance of these lesions.

Early findings in central areolar choroidal dystrophy

We examined 69 members of two caucasian families with an autosomal dominant form of central areolar choroidal dystrophy using ophthalmoscopy and fundus photography. In five members who had a good visual acuity macular lesions were found. In three of them retinal function tests were performed, which turned out to be normal. These 5 patients underwent fluorescein angiography. Early symptoms of central areolar choroidal dystrophy are small parafoveal hyperfluorescent areas due to retinal pigmentepithelium loss and areas of pigment mottling in the macula. Until now the early lesions of central areolar choroidal dystrophy in patients with a good visual acuity in both eyes have not been described clearly.