Analysis of autofluorescent retinal images and measurement of atrophic lesion growth in Stargardt disease.

Current retinal imaging techniques using scanning laser ophthalmoscopy (SLO) provide a powerful mechanism for characterizing the topographical distribution of lipofuscin fluorophores and atrophic lesions (ALs) in retinal disease. In this paper we describe a novel Edge-Flow-Driven Variational Image Segmentation analysis to measure and evaluate progressive change in the area of ALs as well as regions of hyperfluorescence (HF). The algorithm is embedded in a series of almost completely automated image processing steps that allow rapid comparison of serial images. The sensitivity of the methodology to detect change was evaluated by measuring progression of AF lesion size in a cohort of Stargardt Macular Dystrophy (STGD) patients. Fifty-two STGD subjects (mean age = 41.0 +/- 16.6 years, range 9-78 yrs) at varying stages of disease participated in this prospective study. Twenty-four of the 52 subjects presented with atrophic lesions in one or both eyes on first evaluation. For this subgroup of subjects, the mean (+/-1 sd) follow-up time was 2.92 (+0.26) years (range 0.57-3.26 years) and the mean (+/-1 sd) rate of change was found to be approximately 0.94 (+/-0.87) mm(2)/year (range 0.2-2.13 mm(2)/yr). With this methodology, progressive enlargement of AL area was detectable in as little as one year, while regions of HF generally decreased, although there was considerable variability in the appearnce of HF, presumably reflecting the combined effects of the creation or expansion of lipofuscin deposits and resorption and loss associated with retinal cell death. Our findings suggest that this methodology is sufficiently sensitive to detect change and provides a clinically relevant tool to monitor progression not only with regards to natural history, but also to evaluate the efficacy of potential therapeutic interventions in STGD. Finally, we evaluated the association between AL area and measures of rod- and cone-mediated retinal function, as assessed with electroretinography (ERG). In general, the larger the AL, the poorer the ERG response, with a greater impact of lesion size on cone- rather than rod-mediated retinal function, a finding that was expected on the basis of the location and size of the AL and the distribution of rod- and cone-photoreceptors.

Sequence analysis and exclusion of phosducin as the gene for the recessive retinal degeneration of the Abyssinian cat.

Phosducin was evaluated as a candidate gene for the recessive retinal degeneration in the Abyssinan cat, rdAc, using reverse transcription and polymerase chain amplification. The nucleotide sequence of the cat phosducin coding region was determined except for 23 bp at the 5' end. Single-strand conformation analysis of a silent polymorphism within the coding region established the nonlinkage of the phosducin gene with the rdAc locus.

Tamoxifen-associated eye disease. A review.

PURPOSE: The oral antiestrogen tamoxifen has demonstrated efficacy in the treatment of metastatic breast cancer and as adjuvant therapy in early-stage disease. Clinical trials of tamoxifen in chemoprevention of breast cancer among high-risk women have focused attention on potential adverse effects of long-term tamoxifen use, including the possibility of ocular toxicity. This review evaluates the published case reports, clinical series, and clinical trial data on ocular toxicities attributed to tamoxifen. Clinical issues of surveillance, differential diagnosis, and management of tamoxifen-related eye disease are discussed. DESIGN: National Library of Medicine online bibliographic services were used to identify case reports and clinical studies of ocular adverse effects that occurred in patients receiving tamoxifen published through the fall of 1994. The medical literature relevant to issues raised by the reports and studies was similarly identified and reviewed. RESULTS: Case reports and case series identify crystalline retinal deposits, macular edema, and corneal changes as potential tamoxifen ocular toxicities. Extensive retinal lesions and macular edema with visual impairment have been reported in a few patients receiving high-dose tamoxifen. Less extensive retinal changes may occur in patients receiving low doses for long periods, and isolated retinal crystals may be observed in patients without visual symptoms. CONCLUSION: Ocular toxicity is uncommon in the current clinical setting of long-term, low-dose tamoxifen use. Physicians should be aware of the potential for ocular toxicity among patients receiving the drug and should assure appropriate surveillance and prompt evaluation of visual complaints.

A new genetic locus for X linked progressive cone-rod dystrophy.

X linked progressive cone-rod dystrophy (COD) is a retinal disease primarily affecting the cone photoreceptors. The disease is genetically heterogeneous and two loci, COD1 (Xp21.1-11.4) and COD2 (Xq27.2-28), have been previously identified. COD1 was recently shown to be caused by mutations in RPGR exon ORF15 (Xp21.1), the gene that is also responsible for RP3 type retinitis pigmentosa. In this study, we performed a linkage study to map the disease gene in a large Finnish family with X linked cone-rod dystrophy, using a panel of 39 X chromosomal markers. Several recombinations between the disease gene and markers in the Xp21.1-p11.4 region have excluded COD1 as a candidate locus in this family. Consistent with the linkage results, no mutation was detected by direct PCR sequencing of the coding region of RPGR, including exon ORF15. The COD2 locus has been also excluded as the site of the gene on the basis of negative lod score values obtained for COD2 linked markers. The disease causing gene of the studied COD family has been localised between the markers DXS10042 and DXS8060 on Xp11.4-q13.1. Positive pairwise lod scores >3 were obtained for markers DXS993, MAOB, DXS1055, and DXS1194. Since this locus is distinct from the previously identified two loci, COD1 and COD2, our results establish a new third genetic locus for X linked progressive cone-rod dystrophy and further expands our knowledge about the genetic heterogeneity underlying this disease entity.

Novel mutations of the RPGR gene in RP3 families.

X-linked retinitis pigmentosa is a severe retinal degeneration characterized by night blindness and visual field constriction, leading to complete blindness within the third decade of life. Mutations in the RPGR gene (retinitis pigmentosa GTPase regulator), located on Xp21.1 in the RP3 region, have been associated with an RP phenotype. Further to our previous mutation screening of RPGR in families segregating with the RP3 locus, we have expanded this study to include other 8 RP3 pedigrees. Here we report the results of this expanded study and the identification of five mutations in RPGR, four of which are novel (IVS6+5 G>A, 950-951delAA, 963 T>C, EX8del) and one of which occurs in the donor splice site of intron 1 (IVS1+1 G>A). These findings bring the proportion of "RP3 genotypes" with a mutation in this gene to 27% (10/37). Hum Mutat 15:386, 2000.

Central nervous system involvement in Von Hippel-Lindau disease.

Fifty individuals with Von Hippel-Lindau disease (VHL) were studied with gadolinium-enhanced magnetic resonance imaging (MRI) to determine the frequency and distribution of CNS lesions. The associated clinical features were also reviewed. Thirty-six (72%) of the 50 had 1 or more CNS tumors. The most frequently affected sites in the CNS excluding the retina were the cerebellum (52%), spinal cord (44%), and brainstem (18%). New regional predilections for the craniocervical junction and conus medullaris were demonstrated by this study. Forty-one percent of all VHL patients with CNS tumors were neurologically asymptomatic: cerebellar tumors (50%), spinal cord tumors (50%), and brainstem tumors (44%) were often without clinical signs or symptoms. Multiple lesions were common. The mean age of all VHL patients (34.5 years) was similar to the mean age of all CNS VHL patients (34.4 years), suggesting a lack of age association. CNS lesions commonly occurred in the 2nd decade of life. All patients at risk for VHL should be evaluated using gadolinium-enhanced MRI after 10 years of age, although ophthalmic examination should be initiated within the 1st 2 years of life. Enhanced MRI is particularly useful in the detection of CNS tumors in patients with the VHL gene.

The gene for the major intrinsic protein (MIP) of the ocular lens is assigned to human chromosome 12cen-q14.

The gene for the human major intrinsic protein (MIP) of the ocular lens fiber membrane has been assigned to region cen-q14 of chromosome 12 through the use of somatic cell hybrids containing the whole chromosome and parts of human chromosome 12.

Evidence for a new locus for X-linked retinitis pigmentosa (RP23).

PURPOSE: X-linked retinitis pigmentosa (XLRP) is a degenerative disease of the retina characterized in the early stages of disease by night blindness as a result of rod photoreceptor loss, progressing to severe disease with loss of central vision by the third decade in affected males. XLRP displays exceptional genetic heterogeneity, with five reported loci on the human X-chromosome. To investigate the level of heterogeneity for XLRP in the patient pool in the current study, extensive haplotype analysis, linkage analysis, and mutation screening were performed. METHODS: Haplotype analysis of a family with diagnosed XLRP was scored with more than 34 polymorphic markers spanning the entire X-chromosome, including regions already identified as harboring XLRP genes and retina-specific genes. Two-point and multipoint lod scores were calculated. Affected male DNA was amplified with primers specific for the retinoschisis gene (XLRS1), and the products were screened for nucleic acid alterations by direct automated sequencing. RESULTS: In this article haplotype and linkage data are presented identifying a new locus for XLRP on the short arm of the X-chromosome, distinct from previously reported gene localizations for XLRP. The phenotype is atypical, in that the onset of vision loss in the male members of this family is unusually early, and female obligate carriers have normal fundi and waveforms. Informative recombination events in this family define a locus for XLRP (RP23) on Xp22 between the markers DXS1223 and DXS7161, spanning approximately 15 cM. A maximum lod score of 2.1 was calculated for the locus order DXS7103-8 cM-(RP23/DXS1224)-4 cM-DXS999. This new locus (RP23) encompasses the retinoschisis disease gene; therefore, XLRS1 was screened for a mutation. No sequence alteration was identified indicating that mutations in the coding region of the gene responsible for retinoschisis do not cause RP23. CONCLUSIONS: The results describe evidence for a new locus for XLRP (RP23), adding to the established genetic heterogeneity for this disease and the number of genes expressed in ocular tissue residing on the X-chromosome.

Identification, genomic structure, and screening of the vacuolar proton-ATPase membrane sector-associated protein M8-9 gene within the COD1 critical region (Xp11.4).

PURPOSE: Our goal is to identify the gene responsible for X-linked cone-rod dystrophy (COD1) that has been localized to a limited region of Xp11.4. METHODS: A complete physical contig of the COD1 region was partially sequenced and subjected to BLAST searches to identify homologies with GenBank ESTs. ESTs were analyzed for overlapping or related cDNA sequences and retinal expression by PCR screening of multiple human retina cDNA libraries. RACE was performed to complete the missing 5' end of the transcripts. Transcripts were compared with genomic sequences to specify intron-exon boundaries. Genomic DNAs from COD1-affected males from 3 families were screened for mutations using direct PCR sequencing of the exons. RESULTS: The vacuolar proton-ATPase membrane sector-associated protein M8-9 (APT6M8-9) gene was identified within our critical region. We confirmed its retinal expression and its genomic location in our physical contig. Eight exons (with flanking intronic sequences) were characterized from partial cDNA sequence and genomic sequence data. An additional 5' end exon was identified using RACE. No mutations were found in the COD1-affected males. CONCLUSIONS: The combination of disease mapping and information from the Human Genome project has enabled us to identify candidate genes within the COD1 region, including APT6M8-9 gene. We found no evidence that this gene is responsible for COD1 in our families, but it may be an important candidate for other diseases that have been mapped to this region of the X chromosome.

The genetics of age-related macular degeneration.

Age-related macular degeneration (AMD) is increasingly recognized as a complex genetic disorder in which one or more genes contribute to an individual's susceptibility for developing the condition. Twin and family studies as well as population-based genetic epidemiologic methods have convincingly demonstrated the importance of genetics in AMD, though the extent of heritability, the number of genes involved, and the phenotypic and genetic heterogeneity of the condition remain unresolved. The extent to which other hereditary macular dystrophies such as Stargardts disease, familial radial drusen (malattia leventinese), Best's disease, and peripherin/RDS-related dystrophy are related to AMD remains unclear. Alzheimer's disease, another late onset, heterogeneous degenerative disorder of the central nervous system, offers a valuable model for identifying the issues that confront AMD genetics.

Spectrum of malignancy and premalignancy in Carney syndrome.

Carney syndrome is a rare, autosomal dominant, multi-system disorder comprising 8 well-characterized findings, only 2 of which need be present for a definitive diagnosis. Benign neoplasms are frequent, but malignancies are thought to be uncommon. We have studied a family to clarify the diagnosis and spectrum of clinical manifestations of the syndrome and to develop guidelines for management. The proposita, a 34-year-old woman had classic findings of Carney syndrome, invasive follicular carcinoma of the thyroid gland, Barrett metaplasia of the esophagus, neoplastic colonic polyps, bipolar affective disorder, and atypical mesenchymal neoplasm of the uterine cervix distinct from the myxoid uterine leiomyoma usually seen in this syndrome. Although thyroid gland neoplasm is rare in Carney syndrome, this patient's most aggressive manifestation was her thyroid carcinoma. The diagnosis of Carney syndrome was established in her 9-year-old son and is a probable diagnosis in her 12-year-old daughter. Endocrine manifestations were prominent in the family with at least 9 relatives in 3 generations affected with various endocrine abnormalities. The findings in this family indicate that the spectrum of manifestations in this pleiotropic gene apparently includes a malignant course with premalignant and endocrinologic disorders not previously recognized.

A gene responsible for the pigment dispersion syndrome maps to chromosome 7q35-q36.

OBJECTIVES: To demonstrate the inheritance of the pigment dispersion syndrome in 4 families and to determine the location of a gene responsible for this syndrome. PATIENTS: Fifty-four members of 4 families affected by the pigment dispersion syndrome and pigmentary glaucoma. All 4 families are white. Two of the pedigrees are of Irish descent, and 2 are of mixed western European descent that includes some Irish ancestry. INTERVENTIONS: Individuals from 4 pedigrees affected by the pigment dispersion syndrome and their spouses were clinically examined for evidence of the pigment dispersion syndrome. DNA samples from patients and appropriate family members were used for a genome screen using microsatellite repeat markers distributed throughout the human genome. Genotypes were used for linkage analysis to identify markers segregating with the disease trait. RESULTS: Twenty-eight patients showed clinical evidence of the pigment dispersion syndrome. Of these, 14 also had elevated intraocular pressures requiring medical or surgical treatment or both. Significant linkage was observed between the disease phenotype and markers located on the telomere of the long arm of human chromosome 7 (i.e., 7q35-q36). The maximum 2-point lod score (i.e., Zmax) for a single pedigree (i.e., PDS5) was 5.72 at theta = 0 for markers D7S2546 and D7S550. An analysis of affected recombinant individuals demonstrated that the responsible gene is located in a 10-centimorgan interval between markers D7S2462 and D7S2423. CONCLUSIONS: The pigment dispersion syndrome was found to be inherited as an autosomal dominant trait in 4 affected pedigrees. The gene responsible for the syndrome in these 4 families maps to the telomeric end of the long arm of chromosome 7 (i.e., 7q35-q36). Locating a gene responsible for this condition is the first step toward the isolation of the gene itself. Characterization of the responsible gene will help elucidate the pathophysiology of this disease and potentially will lead to new methods of diagnosis and treatment.

Recurrence of a choroidal neovascular membrane in a patient with punctate inner choroidopathy treated with daily doses of thalidomide.

PURPOSE: To determine whether thalidomide therapy can prevent a recurrence of a choroidal neovascular membrane in a patient with punctate inner choroidopathy. METHODS: Case report. In a 38-year-old woman with bilateral punctate inner choroidopathy, thalidomide therapy was initiated three days after laser photocoagulation of a choroidal neovascular membrane. RESULTS: The patient had a recurrence of the choroidal neovascular membrane eight months after the start of thalidomide therapy. CONCLUSIONS: The failure of thalidomide to prevent a recurrence of a choroidal neovascular membrane in this patient suggests that this medication may have only a limited benefit in preventing recurrences of choroidal neovascular membranes.

Clinical spectrum of chromosome 6-linked autosomal dominant drusen and macular degeneration.

PURPOSE: To describe the clinical phenotype and the intrafamilial variation in retinal findings in a North American family with an autosomal dominant drusen disorder that maps to chromosome 6q14. METHODS: Ophthalmic examinations were carried out on participating family members. Fundus photographs were obtained whenever possible. Electroretinography was performed on the proband and her father. Blood was drawn for DNA analysis. RESULTS: Twelve family members had drusen and/or atrophic macular degeneration. The disease in asymptomatic young adults is characterized by fine drusen that are most conspicuous in the macula. The proband presented at 3 years of age with atrophic maculopathy and drusen. Her cousin was found to have atrophic macular lesions and drusen in the first year of life. Two older affected individuals have reduced vision from cicatricial and atrophic macular changes. The gene for the disease was mapped to chromosome 6q14 and appears to be adjacent to but distinct from the locus for North Carolina macular dystrophy. CONCLUSIONS: There is extreme variability in the clinical expression of this dominant form of drusen and macular degeneration. Most young adults have fine macular drusen and good vision. Affected infants and children may have congenital atrophic maculopathy and drusen. There is historical evidence of progression of the disease in late adulthood with moderate visual loss.

Detection of the carrier state of X-linked retinoschisis.

We determined the extent of suppressive rod-cone interaction in 11 obligate carriers and eight potential carriers of X-linked retinoschisis from eight families. Despite otherwise normal ophthalmoscopic and functional testing, all of the obligate heterozygous carriers demonstrated a complete absence of normal rod-cone interaction. Of the potential heterozygous carriers, three had normal rod-cone interactions, two had no detectable interaction, and two yielded technically unsatisfactory results. This lack of rod-cone interactions allows heterozygous individuals to be identified clinically and has implications concerning the origin of this inherited disorder.

A new locus for dominant drusen and macular degeneration maps to chromosome 6q14.

PURPOSE: To report the localization of a gene causing drusen and macular degeneration in a previously undescribed North American family. METHODS: Genetic mapping studies were performed using linkage analysis in a single family with drusen and atrophic macular degeneration. RESULTS: The clinical manifestations in this family ranged from fine macular drusen in asymptomatic middle-aged individuals to atrophic macular lesions in two children and two elderly patients. We mapped the gene to chromosome 6q14 between markers D6S2258 and D6S1644. CONCLUSIONS: In a family with autosomal dominant drusen and atrophic macular degeneration, the gene maps to a 3.2-cM region on chromosome 6q14. This locus appears to be distinct from, but adjacent to, the loci for cone-rod dystrophy 7 (CORD7) and North Carolina macular dystrophy (MCDR1). Future identification of the gene responsible for the disease in this family will provide a better understanding of macular degeneration.

Age-related maculopathy: an expanded genome-wide scan with evidence of susceptibility loci within the 1q31 and 17q25 regions.

PURPOSE: We seek to identify genetic loci that contribute to age-related maculopathy susceptibility. METHODS: Families consisting of at least two siblings affected by age-related maculopathy were ascertained using eye care records and fundus photographs. Additional family members were used to increase the power to detect linkage. Microsatellite genotyping was conducted by the National Heart, Lung and Blood Institute Mammalian Genotyping Service and the National Institutes of Health Center for Inherited Disease Research. Linkage analyses were conducted with parametric (autosomal dominant; heterogeneity lod score) and nonparametric methods (S(all) statistic) using three diagnostic models. False-positive rates were determined from simulations using actual pedigrees and genotyping data. RESULTS: Under our least stringent diagnostic model, model C, 860 affected individuals from 391 families (452 sib pairs) were genotyped. Sixty-five percent of the affected individuals had evidence of exudative disease. Four regions, 1q31, 9p13, 10q26, and 17q25, showed multipoint heterogeneity lod scores or S(all) scores of 2.0 or greater (under at least one model). Under our most stringent diagnostic model, model A, the 1q31 heterogeneity lod score was 2.46 between D1S1660 and D1S1647. Under model C, the 17q25 heterogeneity lod score at D17S928 was 3.16. Using a threshold of 1.5, additional loci on chromosomes 2 and 12 were identified. CONCLUSIONS: The locus on chromosome 1q31 independently confirms a report by Klein and associates mapping an age-related maculopathy susceptibility gene to this region. Simulations indicate that the 1q31 and 17q25 loci are unlikely to be false positives. There was no evidence that other known macular or retinal dystrophy candidate gene regions are major contributors to the genetics of age-related maculopathy.

Long-term tamoxifen citrate use and potential ocular toxicity.

PURPOSE: To estimate the prevalence of abnormalities in visual function and ocular structures associated with the long-term use of tamoxifen citrate. METHODS: A single-masked, cross-sectional study involving multiple community and institutional ophthalmologic departments was conducted with a volunteer sample of 303 women with breast cancer currently taking part in a randomized clinical trial to determine the efficacy of tamoxifen (20 mg/day) in preventing recurrences. Participants included women who had never been on drug (n=85); women who had taken tamoxifen for an average of 4.8 years, then been off the drug for an average of 2.7 years (n=140); and women who had been on tamoxifen continuously for an average of 7.8 years (n=78). Women were evaluated by questionnaire, psychophysical testing, and clinical examination to determine any abnormalities in visual function and the comparative prevalences of corneal, lens, retinal, and optic nerve pathology. RESULTS: There were no cases of vision-threatening ocular toxicity among the tamoxifen-treated participants. Compared with nontreated participants, the tamoxifen-treated women had no differences in the activities of daily vision, visual acuity measurements, or other tests of visual function except for color screening. Intraretinal crystals (odds ratio [OR]=3.58, P=.178) and posterior subcapsular opacities (OR=4.03, P=.034) were more frequent in the tamoxifen-treated group. CONCLUSIONS: Women should have a thorough baseline ophthalmic evaluation within the first year of initiating tamoxifen therapy and receive appropriate follow-up evaluations.

Angioid streaks associated with abetalipoproteinemia.

Angioid streaks were observed in two patients with abetalipoproteinemia. The progression of the angioid streaks was minimal over the years that these patients received vitamin A and E supplementation, though in one patient the development of subretinal neovascular membranes within the angioid streaks was the cause of rapid central visual loss. The simultaneous appearance of two rare entities in unrelated individuals strengthens the relationship between these two disorders that has been suggested by previous case studies. The authors propose a common metabolic pathway involving trace element deficiencies that may account for this relationship as well as the association of angioid streaks with other rare disorders such as Paget's disease, hypoparathyroidism, lead poisoning, hyperphosphatemia, and a number of hemoglobinopathies. Their study of these two patients underscores the need for further investigations as to the role of copper, zinc and omega-3 fatty acids in the pathogenesis of retinopathy in abetalipoproteinemia.

A practice-based survey of familial age-related maculopathy.

PURPOSE: We evaluated the efficacy of a practice-based survey of age-related maculopathy (ARM) to identify potential families for molecular genetic studies. Demographic and ophthalmic features of the eligible study population were compared with responders and with individuals who reported a positive family history of ARM. METHODS: Individuals seen within a three-year period in a comprehensive ophthalmic practice were identified through billing codes. Clinical records were reviewed, coded, and merged with questionnaire responses. Patient identifiers were removed prior to analyses. RESULTS: There were no significant differences between the respondents and the eligible cohort with respect to gender, age, or type of macular degeneration. Comparable percentages of younger and older individuals with ARM reported positive family histories. The distribution of atrophic macular degeneration, choroidal neovascular membranes, and milder forms of the disease among the individuals reporting positive family histories corresponded to the distribution of the entire eligible cohort of patients. CONCLUSIONS: This recruitment strategy for ARM families is cost-effective and confirmed a high prevalence of familial ARM. The respondents are representative of the general ARM population. This approach is applicable for other ophthalmic genetic conditions.