SAXS models of TGFBIp reveal a trimeric structure and show that the overall shape is not affected by the Arg124His mutation.

Human transforming growth factor ß induced protein (TGFBIp) is composed of 683 residues, including an N-terminal cysteine-rich (EMI) domain, four homologous fasciclin domains, and an Arg-Gly-Asp (RGD) motif near the C-terminus. The protein is of interest because mutations in the TGFBI gene encoding TGFBIp lead to corneal dystrophy (CD), a condition where protein aggregates within the cornea compromise transparency. The complete three-dimensional structure of TGFBIp is not yet available, with the exception of a partial X-ray structure of the archetype FAS1 domain derived from Drosophila fasciclin-1. In this study, small-angle X-ray scattering (SAXS) models of intact wild-type (WT) human TGFBIp and a mutant (R124H) are presented. The mutation R124H leads to a variant of granular CD. The deduced structure of the TGFBIp monomer consists of four FAS1 domains in a simple "beads-on-a-string" arrangement, constructed by the superimposition of four consecutive Drosophila fasciclin domains. The SAXS-based model of the TGFBIp R124H mutant displayed no structural differences from WT. Both WT TGFBIp and the R124H mutant formed trimers at higher protein concentrations. The similar association properties and three-dimensional shape of the two proteins suggest that the mutation does not induce any major structural rearrangements, but points towards the role of other corneal-specific factors in the formation of corneal R124H deposits.

[The IC3D classification of the corneal dystrophies]. / IC3D-Klassifikation von Hornhautdystrophien.

BACKGROUND: The recent availability of genetic analyses has demonstrated the shortcomings of the current phenotypic method of corneal dystrophy classification. Abnormalities in different genes can cause a single phenotype, whereas different defects in a single gene can cause different phenotypes. Some disorders termed corneal dystrophies do not appear to have a genetic basis. PURPOSE: The purpose of this study was to develop a new classification system for corneal dystrophies, integrating up-to-date information on phenotypic description, pathologic examination, and genetic analysis. METHODS: The International Committee for Classification of Corneal Dystrophies (IC3D) was created to devise a current and accurate nomenclature. RESULTS: This anatomic classification continues to organize dystrophies according to the level chiefly affected. Each dystrophy has a template summarizing genetic, clinical, and pathologic information. A category number from 1 through 4 is assigned, reflecting the level of evidence supporting the existence of a given dystrophy. The most defined dystrophies belong to category 1 (a well-defined corneal dystrophy in which a gene has been mapped and identified and specific mutations are known) and the least defined belong to category 4 (a suspected dystrophy where the clinical and genetic evidence is not yet convincing). The nomenclature may be updated over time as new information regarding the dystrophies becomes available. CONCLUSIONS: The IC3D Classification of Corneal Dystrophies is a new classification system that incorporates many aspects of the traditional definitions of corneal dystrophies with new genetic, clinical, and pathologic information. Standardized templates provide key information that includes a level of evidence for there being a corneal dystrophy. The system is user-friendly and upgradeable and can be retrieved on the website www.corneasociety.org/ic3d .

[Corneal macular dystrophy: clinical, histopathologic and ultrastructural features]. / Distrofia macular corneal: características clínicas, histopatológicas y ultraestructurales.

OBJECTIVE: To assess the main clinical, genetic, histopathological and ultrastructural features of Mexican patients with macular corneal dystrophy, and to compare the results with those previously reported. METHOD: We analyzed six cases where a histopathologic diagnosis of macular corneal dystrophy had been made between 1957 and 2004. RESULTS: Clinically, all corneas showed focal grayish-white stromal opacities with diffuse edges. Histopathologically, intrastromal granules stained strongly positive with Alcian blue and colloidal iron. Transmission electron microscopy showed enlargement of smooth endoplasmic reticulum and the presence of intracytoplasmic vacuoles that corresponded to glycosaminoglycans. Genetic analysis showed novel mutations in the CHST6 gene in 2 of the patients. CONCLUSIONS: Females were more affected than males and the mean age at the time of diagnosis was older than that reported previously, however the clinical, histopathological and ultrastructural features were similar to those of previous reports. As described in other cases in the literature, in some instances a disorder is found in CHST6 gene as a basis for this condition.

Allelic heterogeneity of the carbohydrate sulfotransferase-6 gene in patients with macular corneal dystrophy.

Allelic heterogeneity of the carbohydrate sulfotransferase-6 gene in patients with macular corneal dystrophy. Macular corneal dystrophy (MCD) is an autosomal recessive disorder characterized by grayish white opacities in the cornea. It is caused by mutations in the carbohydrate sulfotransferase-6 (CHST6) gene, which codes for the enzyme corneal N-acetylglucosamine-6-sulfotransferase. This enzyme catalyzes the sulfation of keratan sulfate, an important component of corneal proteoglycans. We screened 31 patients from 26 families with MCD for mutations in the coding region of the CHST6 gene. Twenty-six different mutations were identified, of which 14 mutations are novel. The novel mutations are one nonsense mutation found in one patient (Trp2Ter), one frameshift (insertion plus deletion) mutation in two patients (His335fs), and 12 missense mutations (Leu3Met, Ser54Phe, Val56Arg, Ala73Thr, Ser98Leu, Cys165Trp, Ser167Phe, Phe178Cys, Leu193Pro, Pro204Arg, Arg272Ser, and Arg334Cys) in 11 patients. These data demonstrate a high degree of allelic heterogeneity of the CHST6 gene in patient populations with MCD from Southern India, where this disease may have a relatively higher prevalence than in outbred communities.

Corneal toxicity secondary to inadvertent use of benzalkonium chloride preserved viscoelastic material in cataract surgery.

AIMS: To study the long term toxic effects of intraocular benzalkonium chloride (BAC). METHODS: 19 patients exposed to intraocular BAC preserved viscoelastic during cataract surgery in February 1999 developed severe striate keratopathy immediately postoperatively. 16 patients, including two who underwent penetrating keratoplasty, were studied in the period April to June 2000. Ocular symptoms, visual acuity, biomicroscopy, intraocular pressure, dilated funduscopy, specular endothelial microscopy, and corneal pachymetry findings were recorded. The corneal and iris specimens of the two patients who underwent keratoplasty were studied by light, transmission, and scanning electron microscopy. RESULTS: Six males and 10 females, aged 64-98 years, were studied 14-16 months postoperatively. All patients were symptomatic. 12 patients had best corrected visual acuity of 6/12 or better and four patients of between 6/18 and 6/60. Five patients had corneal epithelial oedema and 11 had Descemet's membrane folds. The central corneal thickness, 620 (SD 71) microm, in affected eyes was significantly higher (p<0.005, two tailed paired t test) than that of the contralateral eyes, 563 (SD 48) microm. The endothelial cell density was significantly lower (p<0.0001, two tailed paired t test) in affected eyes: 830 (SD 280) cells/mm2 v 2017 (SD 446) cells/mm2. The mean average cell area was significantly higher in the BAC treated eyes: 1317 (SD 385) microm2 v 521 (SD 132) microm2. There was no significant difference in the coefficient of variation of cell size between the two eyes (p=0.3, two tailed paired t test). Two corneal specimens displayed morphological features of bullous keratopathy and other non-specific abnormalities. Extracellular melanosomes were present in a portion of the iris of one case. CONCLUSION: BAC is toxic to the corneal endothelium when used intraocularly, leading to severe striate keratopathy. This cleared in most cases but left varying degrees of residual stromal thickening in all eyes. If penetrating keratoplasty is required the results are excellent.

Non-invasive observation of repeated adenoviral GFP gene delivery to the anterior segment of the monkey eye in vivo.

BACKGROUND: Glaucoma is a group of chronic eye diseases often associated with an elevated intraocular pressure (IOP). If not controlled, the condition leads to blindness. The eye tissue responsible for maintaining aqueous humor resistance and thus normal IOP is the trabecular meshwork (TM). Adenoviral vectors are capable of transducing the TM in several rodent species. Because of the relevance of the non-human primate model in the study of glaucoma, gene transfer to the eyes of cynomolgus monkeys was investigated. METHODS: Four cynomolgus monkeys were injected with AdenoGFP into the anterior chamber: two monkeys received 10(9) pfu and the other two 10(7) pfu. One monkey received four consecutive injections into the same eye (10(7) pfu in each injection) over a 7-month period. In vivo gene transfer (fluorescence) and IOP were evaluated by standard clinical ophthalmic instruments (slit lamp biomicroscopy, gonioscopy and tonometry). Histopathology and cellular distribution were assessed postmortem. RESULTS: The first injection of the lower viral dose resulted in marked TM-preferred gene transfer visible non-invasively by in vivo gonioscopy. The expression of the transgene lasted for 3-4 weeks with little or no signs of clinical inflammation. Gene transfer was achieved on three sequential occasions (3-4 weeks each) but failed and induced substantial, albeit reversible, corneal abnormalities on the fourth occasion. CONCLUSIONS: Gene transfer to the TM and cornea can be monitored non-invasively in non-human primates, allowing correlation of gene transfer with physiological parameters. Because of ocular immune privilege, repeated anterior chamber administrations of adenoviral vectors expressing appropriate genes may have therapeutic potential for glaucoma.

Hereditary benign intraepithelial dyskeratosis: Report of two cases with prominent oral lesions.

Hereditary benign intraepithelial dyskeratosis is a rare autosomal dominant disorder of the oral and ocular mucosa initially described in the Haliwa-Saponi Native American tribe of North Carolina. We describe 2 sisters with the characteristic oral and ocular findings. This entity should be distinguished from several other diseases that cause white lesions in the mouth including white sponge nevus.

Altered fine structures of corneal and skeletal keratan sulfate and chondroitin/dermatan sulfate in macular corneal dystrophy.

The content and fine structure of keratan and chondroitin/dermatan sulfate in normal human corneas and corneas affected by macular corneal dystrophies (MCD) types I and II were examined by fluorophore-assisted carbohydrate electrophoresis. Normal tissues (n = 11) contained 15 microg of keratan sulfate and 8 microg of chondroitin/dermatan sulfate per mg dry weight. Keratan sulfates consisted of approximately 4% unsulfated, 42% monosulfated, and 54% disulfated disaccharides with number of average chain lengths of approximately 14 disaccharides. Chondroitin/dermatan sulfates were significantly longer, approximately 40 disaccharides per chain, and consisted of approximately 64% unsulfated, 28% 4-sulfated, and 8% 6-sulfated disaccharides. The fine structural parameters were altered in all diseased tissues. Keratan sulfate chain size was reduced to 3-4 disaccharides; chain sulfation was absent in MCD type I corneas and cartilages, and sulfation of both GlcNAc and Gal was significantly reduced in MCD type II. Chondroitin/dermatan sulfate chain sizes were also decreased in all diseased corneas to approximately 15 disaccharides, and the contents of 4- and 6-sulfated disaccharides were proportionally increased. Tissue concentrations (nanomole of chains per mg dry weight) of all glycosaminoglycan types were affected in the disease types. Keratan sulfate chain concentrations were reduced by approximately 24 and approximately 75% in type I corneas and cartilages, respectively, and by approximately 50% in type II corneas. Conversely, chondroitin/dermatan sulfate chain concentrations were increased by 60-70% in types I and II corneas. Such changes imply a modified tissue content of individual proteoglycans and/or an altered efficiency of chain substitution on the core proteins. Together with the finding that hyaluronan, not normally present in healthy adult corneas, was also detected in both disease subtypes, the data support the conclusion that a wide range of keratocyte-specific proteoglycan and glycosaminoglycan remodeling processes are activated during degeneration of the stromal matrix in the macular corneal dystrophies.

Multiple recurrences in malignant peripheral nerve sheath tumor of the orbit: a case report and a review of the literature.

PURPOSE: To report the onset of malignant peripheral nerve sheath tumor of the orbit 8 years after irradiation in a patient with neurofibromatosis type-1. METHODS: Case report of a young man with neurofibromatosis type-1 who received irradiation for presumed bilateral optic nerve and chiasmal gliomas and in whom a malignant peripheral nerve sheath tumor later developed. Exenteration with extirpation of the entire contents of the orbit was performed 6 times. RESULTS: Complete recurrence of the tumor occurred after each surgical procedure until the patient died of malignancy. CONCLUSIONS: Our case underscores the risk of irradiation, especially in children with neurofibromatosis type-1, and emphasizes that radiotherapy should never be given as an empirical therapy. The authors believe that irradiation and neurofibromatosis type-1 may, in combination, pose a significant risk for the development of malignancies. Clear-cut indications and a precise tissue diagnosis are desirable before the initiation of radiotherapy, particularly in the pediatric population. We recommend that if irradiation is necessary in persons with neurofibromatosis type-1, regular follow-up is imperative. In view of the hostile nature of malignant peripheral nerve sheath tumor, early aggressive treatment appears to be the only viable alternative at present.

A duplication in chromosome 4q35 is associated with hereditary benign intraepithelial dyskeratosis.

Hereditary benign intraepithelial dyskeratosis (HBID) is an autosomal dominant disorder characterized by elevated epithelial plaques on the ocular and oral mucous membranes. It has been reported primarily, but not exclusively, in individuals of American Indian heritage in North Carolina. We have examined and obtained DNA on two large families affected by HBID. Using genetic linkage analysis we have localized the HBID gene to chromosome 4 (4q35) with a peak LOD score of 8.97. Molecular analysis of these data reveals that all individuals affected with HBID in both families demonstrate the presence of three alleles for two tightly linked markers, D4S1652 and D4S2390, which map to the telomeric region of 4q35. This suggests the presence of a duplication segregating with the disease phenotype that is most likely involved in its causation.

Localized conjunctival argyrosis: a late sequela of strabismus surgery.

We describe a case of focal argyrosis of the conjunctiva clinically simulating a melanoma. An 82-year-old woman was referred for an asymptomatic pigmented conjunctival lesion. Her only significant past ocular history was strabismus surgery 76 years earlier. Biopsy of the conjunctiva and lateral rectus muscle revealed the discoloration was pigment granules. Energy-dispersive x-ray microanalysis revealed the pigmentation to be silver deposits. The patient had strabismus surgery probably using a silver clip. Argyrosis should be considered in the differential diagnosis of focal pigmented conjunctival lesions.

Physical and genetic mapping of the macular corneal dystrophy locus on chromosome 16q and exclusion of TAT and LCAT as candidate genes.

PURPOSE: Macular corneal dystrophy (MCD) is an inherited autosomal recessive disorder that has been subdivided into three immunophenotypes, MCD types I, IA and II. We previously mapped the MCD type I gene to chromosome 16q22 and suggested that the MCD type II gene was linked to the same region. The purpose of this study was to construct a genomic contig spanning the MCD region and to narrow the MCD critical interval by haplotype analysis. The TAT and LCAT genes were mapped to determine if they might be the MCD gene. METHODS: The MCD contig was constructed by screening YAC, PAC, and BAC libraries with microsatellite, STS and EST markers, employing a systematic "DNA walking" technique. Polymorphic markers mapped and ordered on the contig were used to screen the MCD affected individuals and their family members for haplotype analysis. RESULTS: Twenty-two YAC, 30 PAC, and 17 BAC clones were mapped to form the MCD contig. Markers mapped on the contig include 19 microsatellite, 14 STS, and 15 EST markers. Moreover, 18 novel STS markers were generated. Using the mapped and ordered microsatellite markers, haplotype analysis on 21 individuals with MCD type I or type II and their family members from Iceland narrowed the MCD interval to 3 overlapping PAC clones. In addition, the TAT and LCAT genes were mapped outside the MCD region. CONCLUSIONS: We established a genomic contig for the MCD region and dramatically narrowed the MCD critical interval. Mapping data show that the TAT and LCAT genes are not the cause of MCD.

Gliomas of the optic nerve: histological, immunohistochemical (MIB-1 and p53), and MRI analysis.

Gliomas of the optic nerve, although typically of pilocytic (WHO grade I) histology, can present within the spectrum of astrocytic neoplasia including glioblastoma (WHO grade IV). In certain cases, histologic features alone make the distinction between pilocytic and diffuse astrocytomas difficult. We reviewed 22 cases of optic nerve gliomas, 19 of which were pilocytic astrocytomas (PA), and 3 of which were diffuse, non-pilocytic astrocytomas. The cases were evaluated for their clinical course, radiographic appearance, histologic grade, and proliferation indices as detected by MIB-1 (Ki-67) and p53 antibodies. Of the 19 PA, 14 showed no tumor growth by magnetic resonance imaging, and had Ki-67 and p53 labeling indices (LI) of < 1%. The other 5 PA exhibited aggressive behavior manifest by marked diffuse infiltrative tumor growth causing death in 2 patients, 1 of whom was diagnosed with neurofibromatosis type 1 (immunoperoxidase and radiographs not available), and marked local growth with an average time to growth of 39.3 months, a Ki-67 LI of 2-3%, and a p53 LI of < 1% in three others. Three of the five aggressive PA histologically demonstrated a finely reticulated pattern, a pattern that appears as an exaggeration or expansion of the normal neuroglia of the optic nerve, and may simulate a diffuse low-grade astrocytoma. Two demonstrated the coarsely reticulated pattern, with the biphasic and microcystic pattern typical of PA. Three diffuse astrocytomas (2 anaplastic astrocytomas and 1 glioblastoma) originated clinically and radiographically from the optic nerve, and revealed a Ki-67 LI of 2-12%, a p53 LI of 2-8%, and an average time to growth of 8 months. We conclude that the majority of PA of the optic nerve are non-aggressive, stabilize radiographically, and have Ki-67 and p53 LI < 1%. However, a subpopulation of PA has a propensity for aggressive behavior, and are identified by a Ki-67 LI of 2-3% and a p53 LI of < 1%. Diffuse astrocytomas have both Ki-67 and p53 LI > 2%. Thus, in cases of aggressive optic nerve tumors in which the histologic review of biopsy material cannot confidently confirm the diagnosis of pilocytic or diffuse fibrillary glioma, a p53 LI of > 1% appears to favor the diagnosis of diffuse astrocytoma.

Mutations in corneal carbohydrate sulfotransferase 6 gene (CHST6) cause macular corneal dystrophy in Iceland.

PURPOSE: Macular corneal dystrophy (MCD) is subdivided into three immunophenotypes (MCD types I, IA and II). Recently, mutations in the carbohydrate sulfotransferase 6 gene (CHST6) were identified to cause MCD. The purpose of this study was to examine CHST6 for mutations in Icelandic patients with MCD type I. METHODS: Genomic DNA was extracted from leukocytes in the peripheral blood and the coding region of CHST6 was examined for mutations by polymerase chain reaction (PCR) and direct sequencing. RESULTS: Mutation analysis of the CHST6 coding region identified three different mutations in sixteen Icelandic patients with MCD type I. Eleven patients with MCD type I were homozygous for a C1075T mutation. One patient with MCD type I was found to be a compound heterozygous for C1075T and G1189C mutations. One family with MCD type I contained a 10 base pair insertion (ATGCTGTGCG) between nucleotides 707 and 708. In this family, two affected siblings had a homozygous insertion while both their affected mother and their affected maternal aunt had a heterozygous insertion and a heterozygous C1075T mutation. CONCLUSIONS: Three different nucleotide changes were identified in the coding region of CHST6 in sixteen Icelandic patients with MCD type I. All three of these alterations are predicted to affect the translated protein and each of them corresponded to a particular disease haplotype that we had previously reported in this population.

Advances in the molecular genetics of corneal dystrophies.

PURPOSE: To improve our understanding of the role of specific genes on corneal transparency through a review of linkage to specific chromosomal loci and the identification of the mutant genes dealing with the corneal dystrophies. METHOD: Relevant recent literature on the corneal dystrophies is reviewed. RESULTS: Molecular genetic studies of the corneal dystrophies suggest that genes on at least 10 human chromosomes are involved in the maintenance of corneal transparency (chromosomes 1, 5, 9, 10, 12, 16, 17, 20, 21, and X). Within the 10 chromosomes to which corneal dystrophies have been mapped, specific genetic mutations in seven genes (GSN, BIGH3, KRT3, See also pp. 687-691. KRT12, MSS1, GLA, and ARSC1) have been identified in 15 corneal dystrophies. Some corneal dystrophies that are considered distinct clinicopathologic entities are actually caused by different mutations in the same gene. For example, lattice dystrophy types I and IIIA, granular corneal dystrophy types I, II (Avellino dystrophy), and III (Reis-Bucklers dystrophy), and Thiel-Behnke corneal dystrophy are the result of mutations in BIGH3. Mutations in three genes (GSN, BIGH3, MSS1) are associated with amyloid deposition in the cornea. A gene for keratoconus has been mapped to chromosome 21, which is noteworthy because of the established association of keratoconus in Down syndrome (trisomy 21). CONCLUSION: Recent genetic studies on the corneal dystrophies provide insight into some of these disorders at a basic molecular level. Some corneal dystrophies that were previously believed to be distinct clinicopathologic entities are closely related at the molecular level with the different phenotypes resulting from distinct mutations in the same gene. This new knowledge is leading to a revised classification of the corneal dystrophies and to the development of animal models of corneal dystrophies. The latter will lead to a better understanding of the pathogenesis of the disorders and hence to novel therapeutic approaches to those dystrophies that cause significant visual impairment. Research of this nature is only in its infancy.

Cytologic findings in vitreous fluids. Analysis of 74 specimens.

OBJECTIVE: To review the cytologic findings of vitreous specimens and propose a simplified approach to them. STUDY DESIGN: Seventy-four vitreous specimens from 60 patients obtained either during a pars plana vitrectomy or by vitreous aspiration were reviewed. Clinical correlation was obtained on all patients. RESULTS: Findings suggestive of a specific disorder were present in 30 specimens (41%); cytologic examination of the remaining 44 showed nonspecific changes. A lymphoproliferative disorder, the intraocular malignancy suspected most often in this series, was identified in eight specimens (11%). Large cell lymphomas were evident in 5 specimens, 2 specimens were suspicious for lymphoma, and 1 specimen was consistent with plasmacytoma. Twelve specimens (16%) contained hemorrhage. In rare instances, specific infectious agents, such as parasites (5%), bacteria (1%) and fungi (3%), could be identified. The diagnosis of viral infections required ancillary studies. Lens fragments were identified in four cases (5%), and a diagnosis of lens-induced endophthalmitis could be rendered in one case (1%). Changes consistent with sarcoidosis were present in 3% of cases. CONCLUSION: Based on this experience with vitreous specimens submitted for clinical reasons, we found that they could be divided into three broad diagnostic categories: inflammation/infection (54 specimens/41 patients), hemorrhage (12 specimens/12 patients) and malignancy (8 specimens/7 patients).

Immunolocalization of beta ig-h3 protein in 5q31-linked corneal dystrophies and normal corneas.

OBJECTIVE: To characterize the relation of the beta ig-h3 protein to the diagnostic corneal deposits in the hereditary corneal dystrophies recently shown to have mutations in the beta ig-h3 gene on chromosome 5q31. METHODS: Corneas with lattice, granular, mixed granular-lattice ("Avellino"), and 2 types of Reis-Bücklers dystrophy were diagnosed by the histochemical and ultrastructural characteristics of their abnormal aggregates. Dystrophic and normal corneas were compared for immunolocalization of beta ig-h3 protein. RESULTS: In normal corneas, immunoreactivity for beta ig-h3 protein was strongest in the Bowman layer, and next strong along stromal interlamellar junctions and attachment sites of collagen to the Descemet membrane. Antibody binding was intense on all dystrophic aggregates, mimicking somewhat the normal protein distribution. Mixed granular-lattice dystrophy had the most variation in beta ig-h3-immunopositive forms. The aggregates in both the "rod-shaped" Reis-Bücklers type and the "curly fiber" Thiel-Behnke type were strongly stained for beta ig-h3 protein, consistent with mutations on the beta ig-h3 gene. CONCLUSIONS: The marked immunopositivity for beta ig-h3 protein in the abnormal deposits in these dystrophies indicates that beta ig-h3 protein is a major component. The variety and quantity of immunopositive forms suggests that they consist primarily of the mutant protein, self-polymerizing and/or incorrectly binding to other corneal components. Variability of forms may relate to both the specific mutation and regional interactions of this protein.

Sebaceous gland carcinoma: a subtle second malignancy following radiation therapy in patients with bilateral retinoblastoma.

BACKGROUND: Second primary malignancies are common after bilateral retinoblastoma; their estimated incidence has been as high as 51% 50 years after diagnosis. Fifteen patients who developed sebaceous gland carcinoma after radiation therapy have been reported in the literature, five of whom were treated for bilateral retinoblastoma. METHODS: The authors conducted a retrospective chart review of patients treated for bilateral retinoblastoma at Duke University Medical Center who later developed sebaceous gland carcinoma. RESULTS: This article reports two patients who developed sebaceous gland carcinoma after radiation therapy for bilateral retinoblastoma. CONCLUSIONS: Delay in diagnosis is often associated with sebaceous gland carcinoma. Because high mortality is observed with metastatic disease, the recognition of this association is important for anyone who follows patients with a history of bilateral retinoblastoma or prior cranial radiation therapy.