Molecular Biomarkers in Thyroid Eye Disease: A Literature Review

PURPOSE

Thyroid eye disease (TED) is the most common extrathyroidal manifestation of Graves disease. Patients may be severely affected with eyelid retraction, exophthalmos, diplopia, pain, and threatened vision. Autoantibodies against thyroid-stimulating hormone receptor and insulin-like growth factor 1 receptor have shown associations with pathophysiological and clinical traits. Autoantibodies against thyroid-stimulating hormone receptor is in current clinical use as biomarker, but not with unambiguous diagnostic performance. A biomarker with high diagnostic accuracy and/or prognostic capability would be of immense value in diagnosing TED, especially in subclinical cases or when TED precedes the thyroid dysfunction. This article is a literature review on molecular biomarkers of TED.

METHODS

A literature search was performed using PubMed and Embase. Studies on molecular biomarkers in blood, tear fluid, and urine were included in the review.

RESULTS

Forty-six papers were included, of which 30, 14, and 2 studies on biomarkers in blood, tears, and urine, respectively. Fourteen of the papers evaluated the diagnostic performance of various biomarkers, 12 in blood and 2 in tears. Most studies evaluated single biomarkers, but 3 tested a panel of several markers. Except for autoantibodies against thyroid-stimulating hormone receptor, the reported diagnostic performances for the biomarkers were not confirmed in independent cohorts. In 32 studies, no or insufficient performance data were given, but the findings indicated involvement of various biologic mechanisms in TED including inflammation, oxidative stress, fibrosis, lipid metabolism, and ocular surface microflora.

CONCLUSIONS

Currently, serum autoantibodies against thyroid-stimulating hormone receptor is the only molecular biomarker with clinical utility in patients with TED. Several potential biomarkers have been investigated, and particularly panels of multiple biomarkers in tears are promising. To improve patient care, biomarkers in TED should be studied further.

Corneal Vascularization Associated With a Novel PDGFRB Variant

Purpose

The purpose of this study was to identify the genetic cause of aggressive corneal vascularization in otherwise healthy children in one family. Further, to study molecular consequences associated with the identified variant and implications for possible treatment.

Methods

Exome sequencing was performed in affected individuals. HeLa cells were transduced with the identified c.1643C>A, p.(Ser548Tyr) variant in the platelet-derived growth factor receptor beta gene (PDGFRB) or wild-type PDGFRB. ELISA and immunoblot analysis were used to detect the phosphorylation levels of PDGFRβ and downstream signaling proteins in untreated and ligand-stimulated cells. Sensitivity to various receptor tyrosine kinase inhibitors (TKIs) was determined.

Results

A novel c.1643C>A, p.(Ser548Tyr) PDGFRB variant was found in affected family members. HeLa cells transduced with this variant did not have increased baseline levels of phosphorylated PDGFRβ. However, upon stimulation with ligand, excessive activation of PDGFRβ was observed compared to cells transduced with the wild-type variant. PDGFRβ with the p.(Ser548Tyr) amino acid substitution was successfully inhibited with tyrosine kinase inhibitors (axitinib, dasatinib, imatinib, and sunitinib) in vitro.

Conclusions

A novel c.1643C>A, p.(Ser548Tyr) PDGFRB variant was found in family members with isolated corneal vascularization. Cells transduced with the newly identified variant showed increased phosphorylation of PDGFRβ upon ligand stimulation. This suggests that PDGF-PDGFRβ signaling in these patients leads to overactivation of PDGFRβ, which could lead to abnormal wound healing of the cornea. The examined TKIs prevented such overactivation, introducing the possibility for targeted treatment in these patients.

Functional characterization of all-trans retinoic acid-induced differentiation factor (ATRAID)

All-trans retinoic acid-induced differentiation (ATRAID) factor was first identified in HL60 cells. Several mRNA isoforms exist, but the respective proteins have not been fully characterized. In transfected cells expressing Myc-Flag-tagged ATRAID Isoform (Iso) A, B, and C, Iso C was found to be expressed at high levels, Iso A was found to be expressed at low levels due to rapid degradation, and the predicted protein expressed from Iso B was not detected. Iso C was present mainly in an N-glycosylated form. In subcellular fractionation experiments, Iso C localized to the membranous and nuclear fractions, while immunofluorescence analysis revealed that Iso C is located close to the plasma membrane, mainly in cytoplasmic vesicles and in the Golgi area. We confirm that Iso C colocalizes to some extent with endosomal/lysosomal markers LAMP1 and LAMP2. Furthermore, we show that ATRAID co-localizes with RAB11, a GTPase associated with recycling endosomes and implicated in regulating vesicular trafficking.

A Pellino-2 variant is associated with constitutive NLRP3 inflammasome activation in a family with ocular pterygium-digital keloid dysplasia

Ocular pterygium-digital keloid dysplasia (OPDKD) is a rare hereditary disease characterized by corneal ingrowth of vascularized conjunctival tissue early in life. Later, patients develop keloids on fingers and toes but are otherwise healthy. In a recently described family with OPDKD, we report the presence of a de novo c.770C > T, p.(Thr257Ile) variant in PELI2 in the affected individual. PELI2 encodes for the E3 ubiquitin ligase Pellino-2. In transgenic U87MG cells overexpressing Pellino-2 with the p.(Thr257Ile) amino acid substitution, constitutive activation of the NLRP3 inflammasome was observed. However, the Thr257Ile variant did not affect Pellino-2 intracellular localization, its binding to known interaction partners, nor its stability. Our findings indicate that constitutive autoactivation of the NLRP3 inflammasome contributes to the development of PELI2-associated OPDKD.

Systemic Activation of the Kynurenine Pathway in Graves` Disease with and without Ophthalmopathy

PURPOSE

To characterize the kynurenine pathway, activated during interferon-γ mediated inflammation and cellular (Th1-type) immunity, in Graves` disease (GD) patients with and without thyroid eye disease (TED).

METHODS

We analyzed 34 biomarkers by mass spectrometry in serum samples from 100 patients with GD (36 with TED) and 100 matched healthy controls. The analytes included 10 metabolites and three indices from the kynurenine pathway, six microbiota-derived metabolites, 10 B-vitamers and five serum proteins reflecting inflammation and kidney function.

RESULTS

GD patients showed significantly elevated levels of seven biomarkers compared with healthy controls (omega squared (ω2) > 0.06, P < 0.01). Out of these seven, the six biomarkers with the strongest effect size were all components of the kynurenine pathway. Factor analysis showed that biomarkers related to cellular immunity and the Th1 responses (3-hydroxykynurenine, kynurenine and quinolinic acid with the highest loading) were most strongly associated with GD. Further, a factor mainly reflecting acute phase response (CRP and serum amyloid A) showed weaker association with GD by factor analysis. There were no differences in biomarker levels between GD patients with and without TED.

CONCLUSION

This study supports activation of interferon-γ inflammation and Th1 cellular immunity in GD, but also a contribution of acute phase reactants. Our finding of no difference in systemic activation of the kynurenine pathway in GD patients with and without TED implies that the local Th1 immune response in the orbit is not reflected systemically.

Novel inflammatory biomarkers in thyroid eye disease

PURPOSE

The aim of this study is to identify biochemical inflammatory markers predicting the presence or risk of developing thyroid eye disease (TED) in patients with Graves' disease (GD).

METHODS

Patients with GD (n = 100, 77 females) were included from the National Norwegian Registry of Organ-Specific Diseases. Serum samples were analysed for 92 different inflammatory biomarkers using the proximity extension assay. Biomarker levels were compared between groups of patients with and without TED and healthy subjects (HS) (n = 120).

RESULTS

TED was found in 36 of 100 GD patients. Significant (P < 0.05) differences in the levels of 52 inflammatory biomarkers were found when GD patients and HS were compared (42 elevated and 10 decreased). Out of the 42 elevated biomarkers, a significantly higher serum level of interleukin-6 (IL6) (P = 0.022) and macrophage colony-stimulating factor (CSF1) (P = 0.015) were found in patients with TED compared to patients without TED. Patients with severe TED also had significantly elevated levels of Fms-related tyrosine kinase 3 ligand (FLT3LG) (P = 0.009). Furthermore, fibroblast growth factor 21 (FGF21) was significantly increased (P = 0.008) in patients with GD who had no signs of TED at baseline but developed TED later.

CONCLUSION

We demonstrate an immunologic fingerprint of GD, as serum levels of several inflammation-related proteins were elevated, while others were decreased. Distinctly increased levels of IL6, CSF1, FLT3LG, and FGF21 were observed in TED, suggesting that these inflammatory proteins could be important in the pathogenesis, and therefore potential new biomarkers for clinical use.

Pellino-2 in nonimmune cells: novel interaction partners and intracellular localization

Pellino-2 is an E3 ubiquitin ligase that mediates intracellular signaling in innate immune pathways. Most studies of endogenous Pellino-2 have been performed in macrophages, but none in nonimmune cells. Using yeast two-hybrid screening and co-immunoprecipitation, we identified six novel interaction partners of Pellino-2, with various localizations: insulin receptor substrate 1, NIMA-related kinase 9, tumor necrosis factor receptor-associated factor 7, cyclin-F, roundabout homolog 1, and disheveled homolog 2. Pellino-2 showed cytoplasmic localization in a wide range of nonimmune cells under physiological potassium concentrations. Treatment with the potassium ionophore nigericin resulted in nuclear localization of Pellino-2, which was reversed by the potassium channel blocker tetraethylammonium. Live-cell imaging revealed intracellular migration of GFP-tagged Pellino-2. In summary, Pellino-2 interacts with proteins at different cellular locations, taking part in dynamic processes that change its intracellular localization influenced by potassium efflux.

K+ regulates relocation of Pellino-2 to the site of NLRP3 inflammasome activation in macrophages

Pellino proteins are E3 ubiquitin ligases involved in the innate immune system. Recently, Pellino-2 was reported to modulate the activation of the mouse Nlrp3 inflammasome. We examined the intracellular localization of human Pellino-2 in THP1-derived macrophages during activation with LPS and ATP. We observed that Pellino-2 changed intracellular localization and co-localized with the inflammasome proteins NLRP3 and ASC late in the assembly of the inflammasome. Co-localization with NLRP3 and ASC was also seen in cells maintained in potassium-free medium. The co-localization and inflammasome activation were abrogated by several potassium channel inhibitors, supporting a role for potassium efflux in modulating intracellular localization of Pellino-2. The data suggest that Pellino-2 is essential for mediating the effect of potassium efflux on inflammasome activation.

Clinical features and molecular genetics of patients with ABCA4-retinal dystrophies

PURPOSE

Pathogenic variations in the ABCA4 gene are a leading cause of vision loss in patients with inherited retinal diseases. ABCA4-retinal dystrophies are clinically heterogeneous, presenting with mild to severe degeneration of the retina. The purpose of this study was to clinically and genetically characterize patients with ABCA4-retinal dystrophies in Norway and describe phenotype-genotype associations.

METHODS

ABCA4 variants were detected in 111 patients with inherited retinal disease undergoing diagnostic genetic testing over a period of 12 years. In patients where only a single ABCA4 variant was found, whole-gene ABCA4 sequencing was performed and intronic variants were investigated by mRNA analyses in fibroblasts. Medical journals were used to obtain a clinical description and ultrawidefield autofluorescence images were used to analyse retinal degeneration patterns.

RESULTS

The genetic diagnostic yield was 89%. The intronic splice variant c.5461-10T>C was the most prevalent disease-causing variant (27%). Whole-gene ABCA4 sequencing detected two novel intronic variants (c.6729+81G>T and c.6817-679C>A) that we showed affected mRNA splicing. Peripheral retinal degeneration was identified in 33% of patients and was associated with genotypes that included severe loss of function variants. By contrast, peripheral degeneration was not found in patients with a disease duration over 20 years and genotypes including p.(Asn1868lle), c.4253+43G>A or p.(Gly1961Glu) in trans with a loss of function variant.

CONCLUSION

This study demonstrates the clinical and genetic heterogeneity of ABCA4-retinal dystrophies in Norway. Further, the study presents novel variants and increases our knowledge on phenotype-genotype associations and the presence of peripheral retinal degeneration in ABCA4-retinal dystrophy patients.

Temperature-dependent autoactivation associated with clinical variability of PDGFRB Asn666 substitutions

Ocular pterygium-digital keloid dysplasia (OPDKD) presents in childhood with ingrowth of vascularized connective tissue on the cornea leading to severely reduced vision. Later the patients develop keloids on digits but are otherwise healthy. The overgrowth in OPDKD affects body parts that typically have lower temperature than 37°C. We present evidence that OPDKD is associated with a temperature sensitive, activating substitution, p.(Asn666Tyr), in PDGFRB. Phosphorylation levels of PDGFRB and downstream targets were higher in OPDKD fibroblasts at 37°C but were further greatly increased at the average corneal temperature of 32°C. This suggests that the substitution cause significant constitutive autoactivation mainly at lower temperature. In contrast, a different substitution in the same codon, p.(Asn666Ser), is associated with Penttinen type of premature aging syndrome. This devastating condition is characterized by widespread tissue degeneration, including pronounced chronic ulcers and osteolytic resorption in distal limbs. In Penttinen syndrome fibroblasts, equal and high levels of phosphorylated PDGFRB was present at both 32°C and 37°C. This indicates that this substitution causes severe constitutive autoactivation of PDGFRB regardless of temperature. In line with this, most downstream targets were not affected by lower temperature. However, STAT1, important for tissue wasting, did show further increased phosphorylation at 32°C. Temperature-dependent autoactivation offers an explanation to the strikingly different clinical outcomes of substitutions in the Asn666 codon of PDGFRB.

Vision-related quality of life in patients with occipital stroke

OBJECTIVES

The aim of this study was to detect visual field defects (VFDs) after occipital infarction, investigate the rate of recovery and the impact of VFD upon vision-related quality of life (QoL).

MATERIALS AND METHODS

Multicenter, prospective study including patients with MRI verified acute occipital infarction (NOR-OCCIP project). Ophthalmological examination including perimetry was performed within 2 weeks and after 6 months. Vision-related QoL was assessed by the National Eye Institute Visual Function Questionnaire 25 (VFQ-25) at one and 6 months post-stroke.

RESULTS

We included 76 patients, reliable perimetry results were obtained in 66 patients (87%) at a median of 8 days after admittance and VFD were found in 52 cases (79%). Evaluation of VFD after 6 months revealed improvement in 52%. Patients with VFD had significantly lower composite score in VFQ-25 at both test points (77 vs 96, P = .001 and 87 vs 97, P = .009), in nine out of eleven subscales of VFQ-25 at 1 month and seven subscales after 6 months, including mental health, dependency, near and distance activities. Milder VFD had better results on VFQ-25 modified composite score (95 vs 74, P = .002).VFD improvement was related to improved VFQ-25 modified composite score (9.6 vs 0.8, P = .018). About 10% of patients with VFD reported driving 1 month post-stroke and 38% after 6 months.

CONCLUSION

VFD substantially reduces multiple aspects of vision-related QoL. Severity of VFD is related to QoL and VFD improvement results in better QoL. Neglecting visual impairment after stroke may result in deterioration of rehabilitation efforts. Driving post-stroke deserves particular attention.

Primary Sjögren's syndrome and the eye

Primary Sjögren syndrome is an autoimmune disease that mainly affects exocrine glands such as the salivary and lacrimal glands. In addition, systemic involvement is common. Primary Sjögren syndrome is of particular interest to ophthalmologists as it constitutes an important differential diagnosis in conditions with dry eye disease. In addition, ocular tests for more precisely diagnosing and monitoring primary Sjögren syndrome have become increasingly important, and new therapeutics for local and systemic treatment evolve as a result of increased understanding of immunological mechanisms and molecular pathways in the pathogenesis of primary Sjögren syndrome. We provide an update of interest to ophthalmologists regarding pathogenesis, diagnosis, investigative procedures, and treatment options.

Absence of the proteoglycan decorin reduces glucose tolerance in overfed male mice

Studies have implicated the extracellular matrix (ECM) of adipose tissue in insulin resistance. The proteoglycan decorin, a component of ECM, has been associated with glucose tolerance, but possible causal effects on metabolism remain to be explored. We here sought to determine metabolic consequences of loss of decorin in mice (DcnKO). DcnKO mice were fed a low-fat (LF) or high-fat (HF) diet for 10 weeks and body weight and food intake was recorded. An intraperitoneal glucose tolerance test was performed after eight weeks. Blood samples and adipose, liver and muscle tissues were collected at sacrifice. Global gene expression was measured in adipose tissue, and expression of decorin was also analyzed in human adipose samples. DcnKO mice showed increased feed efficiency during overfeeding and impaired glucose tolerance. Adipose leptin mRNA and circulating leptin levels were elevated in DcnKO mice, along with a downregulation of genes involved in ECM organization and triglyceride biosynthesis, and an upregulation of adipose genes involved in complement and coagulation cascades. Consistent with a protective metabolic role for decorin, in obese patients we found increased adipose decorin expression after profound fat loss, particularly in the stromal vascular fraction. Loss of decorin in mice caused impaired glucose tolerance in association with increased feed efficiency and altered gene expression in adipose tissue. Our data provide evidence that decorin is an important factor for maintaining glucose tolerance.

A tyrosine kinase-activating variant Asn666Ser in PDGFRB causes a progeria-like condition in the severe end of Penttinen syndrome

Missense variants located to the "molecular brake" in the tyrosine kinase hinge region of platelet-derived growth factor receptor-β, encoded by PFGFRB, can cause Penttinen-type (Val665Ala) and Penttinen-like (Asn666His) premature ageing syndromes, as well as infantile myofibromatosis (Asn666Lys and Pro660Thr). We have found the same de novo PDGFRB c.1997A>G p.(Asn666Ser) variants in two patients with lipodystrophy, acro-osteolysis and severely reduced vision due to corneal neovascularisation, reminiscent of a severe form of Penttinen syndrome with more pronounced connective tissue destruction. In line with this phenotype, patient skin fibroblasts were prone to apoptosis. Both in patient fibroblasts and stably transduced HeLa and HEK293 cells, autophosphorylation of PDGFRβ was observed, as well as increased phosphorylation of downstream signalling proteins such as STAT1, PLCγ1, PTPN11/SHP2-Tyr580 and AKT. Phosphorylation of MAPK3 (ERK1) and PTPN11/SHP2-Tyr542 appeared unaffected. This suggests that this missense change not only weakens tyrosine kinase autoinhibition, but also influences substrate binding, as both PTPN11 tyrosines (Tyr542 and Tyr580) usually are phosphorylated upon PDGFR activation. Imatinib was a strong inhibitor of phosphorylation of all these targets, suggesting an option for precision medicine based treatment.

Recurrent, Activating Variants in the Receptor Tyrosine Kinase DDR2 Cause Warburg-Cinotti Syndrome

We have investigated a distinct disorder with progressive corneal neovascularization, keloid formation, chronic skin ulcers, wasting of subcutaneous tissue, flexion contractures of the fingers, and acro-osteolysis. In six affected individuals from four families, we found one of two recurrent variants in discoidin domain receptor tyrosine kinase 2 (DDR2): c.1829T>C (p.Leu610Pro) or c.2219A>G (p.Tyr740Cys). DDR2 encodes a collagen-responsive receptor tyrosine kinase that regulates connective-tissue formation. In three of the families, affected individuals comprise singleton adult individuals, and parental samples were not available for verification of the de novo occurrence of the DDR2 variants. In the fourth family, a mother and two of her children were affected, and the c.2219A>G missense variant was proven to be de novo in the mother. Phosphorylation of DDR2 was increased in fibroblasts from affected individuals, suggesting reduced receptor autoinhibition and ligand-independent kinase activation. Evidence for activation of other growth-regulatory signaling pathways was not found. Finally, we found that the protein kinase inhibitor dasatinib prevented DDR2 autophosphorylation in fibroblasts, suggesting an approach to treatment. We propose this progressive, fibrotic condition should be designated as Warburg-Cinotti syndrome.

Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase

Purpose

To determine the ocular consequences of a dominant-negative mutation in the p85α subunit of phosphatidylinositol 3-kinase (PIK3R1) using a knock-in mouse model of SHORT syndrome, a syndrome associated with short stature, lipodystrophy, diabetes, and Rieger anomaly in humans.

Methods

We investigated knock-in mice heterozygous for the SHORT syndrome mutation changing arginine 649 to tryptophan in p85α (PIK3R1) using physical examination, optical coherence tomography (OCT), tonometry, and histopathologic sections from paraffin-embedded eyes, and compared the findings to similar investigations in two human subjects with SHORT syndrome heterozygous for the same mutation.

Results

While overall eye development was normal with clear cornea and lens, normal anterior chamber volume, normal intraocular pressure, and no changes in the retinal structure, OCT images of the knock-in mouse eyes revealed a significant decrease in thickness and width of the iris resulting in increased pupil area and irregularity of shape. Both human subjects had Rieger anomaly with similar defects including thin irides and irregular pupils, as well as a prominent ring of Schwalbe, goniosynechiae, early cataract formation, and glaucoma. Although the two subjects had had diabetes for more than 30 years, there were no signs of diabetic retinopathy.

Conclusions

A dominant-negative mutation in the p85α regulatory subunit of PI3K affects development of the iris, and contributes to changes consistent with anterior segment dysgenesis in both humans and mice.

The intronic ABCA4 c.5461-10T>C variant, frequently seen in patients with Stargardt disease, causes splice defects and reduced ABCA4 protein level

PURPOSE

Despite being the third most common ABCA4 variant observed in patients with Stargardt disease, the functional effect of the intronic ABCA4 variant c.5461-10T>C is unknown. The purpose of this study was to investigate the molecular effect of this variant.

METHODS

Fibroblast samples from patients carrying the ABCA4 variant c.5461-10T>C were analysed by isolating total RNA, followed by real-time polymerase chain reaction (RT-PCR) using specific primers spanning the variant. For detection of ABCA4 protein, fibroblast samples were lysed and analysed by SDS-PAGE followed by immunoblotting using a monoclonal ABCA4 antibody.

RESULTS

The ABCA4 variant c.5461-10T>C causes a splicing defect resulting in the reduction of full-length mRNA in fibroblasts from patients and the presence of alternatively spliced mRNAs where exon 39-40 is skipped. A reduced level of full-length ABCA4 protein is observed compared to controls not carrying the variant.

CONCLUSIONS

This study describes the functional effect and the molecular mechanism of the pathogenic ABCA4 variant c.5461-10T>C. The variant is functionally important as it leads to splicing defects and a reduced level of ABCA4 protein.

Mutations in MAPKBP1 Cause Juvenile or Late-Onset Cilia-Independent Nephronophthisis

Nephronophthisis (NPH), an autosomal-recessive tubulointerstitial nephritis, is the most common cause of hereditary end-stage renal disease in the first three decades of life. Since most NPH gene products (NPHP) function at the primary cilium, NPH is classified as a ciliopathy. We identified mutations in a candidate gene in eight individuals from five families presenting late-onset NPH with massive renal fibrosis. This gene encodes MAPKBP1, a poorly characterized scaffolding protein for JNK signaling. Immunofluorescence analyses showed that MAPKBP1 is not present at the primary cilium and that fibroblasts from affected individuals did not display ciliogenesis defects, indicating that MAPKBP1 may represent a new family of NPHP not involved in cilia-associated functions. Instead, MAPKBP1 is recruited to mitotic spindle poles (MSPs) during the early phases of mitosis where it colocalizes with its paralog WDR62, which plays a key role at MSP. Detected mutations compromise recruitment of MAPKBP1 to the MSP and/or its interaction with JNK2 or WDR62. Additionally, we show increased DNA damage response signaling in fibroblasts from affected individuals and upon knockdown of Mapkbp1 in murine cell lines, a phenotype previously associated with NPH. In conclusion, we identified mutations in MAPKBP1 as a genetic cause of juvenile or late-onset and cilia-independent NPH.

Temporal hollowing and other adverse effects after lateral orbital wall decompression

PURPOSE

To evaluate the outcome and late postoperative complications after lateral orbital wall decompression in a series of patients with thyroid eye disease (TED).

METHODS

One hundred and three patients operated in the period 1999-2013 were invited to participate in the study, and 84 were included after a median (range) follow-up time of 124 (13-188) months. The patients were interviewed, and preoperative and postoperative data were collected from hospital records. Photographs ('selfies') were obtained from 64 patients. Wilcoxon signed-rank test was used to evaluate the change in pre- and postoperative data.

RESULTS

On average, visual acuity was unchanged with a median value (range) of 1.0 (0.4-1.25) before to 1.0 (0-1.25) after surgery (p = 0.5). Intraocular pressure (IOP) was reduced from a median value (range) of 17 (9-26) to 15 (8-23) mmHg (p < 0.001). Median (range) Hertel values were 23 (15-30) mm preoperatively and 20 (12-26) mm postoperatively (p < 0.001) respectively. Mean (SD) reduction in proptosis was 3.6 (±2.1) mm. Oscillopsia was reported in 24 patients (29%), 42 (50%) experienced a change in temporal sensation, and four (5%) had new-onset diplopia. In 47 patients (56%), some degree of temporal hollowing was reported. Among 64 photographed patients, 38 (59%) had noticeable hollowing on examination of postoperative pictures. There was agreement of the patient's perception of temporal hollowing and the appearance in photographs in 26 of 37 patients (70%).

CONCLUSION

Lateral orbital wall decompression has been considered a safe and effective procedure for treatment of TED. Serious side-effects are infrequent, but in rare circumstances, even blindness may occur. Less serious side-effects are relatively common. Among others, a significant number of the patients developed temporal hollowing after the procedure. The patients must be informed about the possible complications before surgery.

Role of Decorin Core Protein in Collagen Organisation in Congenital Stromal Corneal Dystrophy (CSCD)

The role of Decorin in organising the extracellular matrix was examined in normal human corneas and in corneas from patients with Congenital Stromal Corneal Dystrophy (CSCD). In CSCD, corneal clouding occurs due to a truncating mutation (c.967delT) in the decorin (DCN) gene. Normal human Decorin protein and the truncated one were reconstructed in silico using homology modelling techniques to explore structural changes in the diseased protein. Corneal CSCD specimens were also examined using 3-D electron tomography and Small Angle X-ray diffraction (SAXS), to image the collagen-proteoglycan arrangement and to quantify fibrillar diameters, respectively. Homology modelling showed that truncated Decorin had a different spatial geometry to the normal one, with the truncation removing a major part of the site that interacts with collagen, compromising its ability to bind effectively. Electron tomography showed regions of abnormal stroma, where collagen fibrils came together to form thicker fibrillar structures, showing that Decorin plays a key role in the maintenance of the order in the normal corneal extracellular matrix. Average diameter of individual fibrils throughout the thickness of the cornea however remained normal.

Development of congenital stromal corneal dystrophy is dependent on export and extracellular deposition of truncated decorin

PURPOSE

Congenital stromal corneal dystrophy (CSCD) is an autosomal dominant condition with clouding of the cornea due to stromal opacities. It is caused by mutations in the decorin gene (DCN) leading to the expression of a truncated form of decorin. In an attempt to replicate this condition in mice, a knock-in mouse strain, 952delT Dcn, was created.

METHODS

Mice were constructed by targeted mutation. Sequencing of genomic DNA confirmed correct genotype. Mouse and human corneas, including corneas from patients with CSCD, and primary keratocyte cultures were subjected to Western blot analysis, transmission electron microscopy, and immunofluorescence microscopy.

RESULTS

Histologically, the mice did not show any organ pathology. Corneas were clear, and the electron-lucent deposits observed in CSCD were not present. Furthermore, while nearly equivalent amounts of normal and truncated decorin are present in CSCD corneas, truncated decorin was hardly detectable in the mouse corneas. By immunofluorescence analysis of corneas from 952delT Dcn homozygous mice, decorin was found only in keratocytes. In primary cultures of mouse corneal explants, truncated decorin was retained intracellularly in contrast with human corneal explants where truncated decorin was exported into the culture medium. Immunofluorescence analysis revealed that native mouse decorin localized to the Golgi complex, whereas the truncated decorin accumulated in the endoplasmic reticulum (ER).

CONCLUSIONS

The ER retention of truncated decorin may explain why the mouse corneas remained clear. The consequences of the decorin mutation are different in mice and humans, and 952delT Dcn knock-in mice are therefore not a suitable model for CSCD.

High myopia-excavated optic disc anomaly associated with a frameshift mutation in the MYC-binding protein 2 gene (MYCBP2)

PURPOSE

To investigate the ocular and neurologic manifestations, and to identify the causative mutation in a family with an excavated optic disc anomaly, high myopia, enlarged axial lengths, and abnormal visual evoked response (VER).

DESIGN

Prospective observational case series with whole exome sequencing.

METHODS

Institutional study of 8 family members from 3 generations. Clinical examination included visual field examination, optical coherence tomography, axial length measurement, audiometry, visual evoked response (VER), orbital and cerebral magnetic resonance imaging (MRI), and renal ultrasound. DNA was analyzed by whole exome sequencing and Sanger sequencing. Main outcome measures were clinical and radiological findings, and DNA sequence data.

RESULTS

Three affected family members, a father and his 2 daughters, were examined. The parents and siblings of the father were healthy. Affected individuals presented with excavated optic discs, high myopia (-1.00 to -16.00 diopters), and increased axial lengths. Reduced visual acuity (0.05-0.8) and decreased sensitivity on visual field examination were observed. VER revealed prolonged latency times. Affected eyes appeared ovoid on MRI and the father had thin optic nerves. Exome sequencing revealed that the father was heterozygous for a de novo 5 bp deletion in MYCBP2, c.5906_5910del; p.Glu1969Valfs*26. The same mutation was found in his 2 affected daughters, but not in his parents or siblings, or in public databases.

CONCLUSION

We describe a distinct excavated optic disc anomaly associated with high myopia and increased axial length. The condition appears to follow an autosomal dominant pattern and segregate with a deletion in MYCBP2. We suggest naming this entity high myopia-excavated optic disc anomaly.

Long-term follow-up of patients with thyroid eye disease treated with endoscopic orbital decompression

PURPOSE

To evaluate the outcome of endoscopic decompression in a series of patients with thyroid eye disease.

METHODS

All 46 patients operated at our institution in the period 2001 to 2011 were invited for re-examination. Thirty-seven patients were included in the study and underwent a general otorhinolaryngological and ophthalmological examination. Nasal endoscopy, autoperimetry and a CT scan of the orbits and paranasal sinuses were performed. Preoperative and early postoperative data were obtained from hospital records. Re-examination was performed from 12 months to 9 years postoperatively. Paired t-test was used to evaluate the change in pre- and postoperative data. Image-guided surgery was used in two patients.

RESULTS

Visual acuity improved from a median value (range) of 0.8 (0.05-1.25) to 1.0 (0.4-1.25) (p=0.006). Intra-ocular pressure (IOP) was reduced from a median value (range) of 18 mmHg (10-27 mmHg) to 14 mmHg (8-24 mmHg) (p<0.001). Median (range) Hertel values were 22.5 mm (14-29 mm) preoperatively and 19 mm (11-26 mm) postoperatively (p<0.001). Mean reduction in proptosis was 4.0 mm. At follow-up, visual fields were normal in 16/37 patients (43%) and with small defects in 12/37 patients (32%). Seventeen patients (46%) had diplopia preoperatively in one or more directions of gaze while 9 (24%) suffered from constant diplopia. After endoscopic decompression, new onset diplopia was seen in seven (19%) individuals, while worsening of diplopia occurred in eight (22%). Impaired motility in abduction and/or elevation was seen in 20 (54%) individuals before decompression and in 23 (62%) after. Strabismus surgery was performed in 22 patients. On final examination 85% of the study population were totally free of diplopia or experienced diplopia only in the peripheral field of gaze. Three patients developed sinusitis. Of these, endoscopic sinus surgery was performed in two patients, and one patient was conservatively treated. Symptoms resolved in all three patients.

CONCLUSION

Endoscopic medial orbital decompression including removal of the medial floor of the orbit is a safe and effective procedure for treatment of thyroid eye disease. Navigation can be of valuable help to ensure complete resection of the bony walls. However, the majority of patients will need subsequent strabismus surgery, mainly due to significant increase of esotropia.

Levator recession with adjustable sutures for correction of upper eyelid retraction in thyroid eye disease

PURPOSE

To examine the outcome of levator muscle recession with adjustable sutures for correcting upper eyelid retraction in thyroid eye disease.

METHODS

All patients treated at Haukeland University Hospital between 2001 and 2011 were invited to participate in a follow-up examination. Preoperative measurements were obtained from medical records. The following parameters were recorded: eyelid aperture, the distance from limbus to eyelid margin, vertical motility of the eyelid in up- and downgaze, lagophthalmos, proptosis, vertical motility of the eye, and strabismus. Symmetry and eyelid contour were evaluated from photographs. Results were categorized as good, acceptable or unacceptable.

RESULTS

Sixty-four out of a total of 80 patients attended the follow-up examination. Six were excluded from further analysis due to relapse of their thyroid eye disease with increased inflammation. Among the 58 remaining patients, a good result was observed in 34 patients, an acceptable result in 19 and an unacceptable result in 5. Lagophthalmos was seen in 30% of the lids preoperatively and in 7% postoperatively. A second procedure was performed in 13/80 patients, in 6 because of under-correction and in 7 because of ptosis. Wound infection occurred in 2 patients.

CONCLUSION

Levator recession with adjustable sutures can be used to correct any degree of retraction. Good results can be obtained, but the procedure is time-consuming, and patients must be informed about the risk for reoperation.

Variants of anterior segment dysgenesis and cerebral involvement in a large family with a novel COL4A1 mutation

PURPOSE

To investigate the diverse ocular manifestations and identify the causative mutation in a large family with autosomal dominant anterior segment dysgenesis accompanied in some individuals by cerebral vascular disease.

DESIGN

Retrospective observational case series and laboratory investigation.

METHODS

Forty-five family members from 4 generations underwent ophthalmic examination. Molecular genetic investigation included analysis with single nucleotide polymorphism (SNP) markers and DNA sequencing. Whole exome sequencing was performed in 1 individual.

RESULTS

A broad range of ocular manifestations was observed. Typical cases presented with corneal clouding, anterior synechiae, and iris hypoplasia. Posterior embryotoxon, corectopia, and early cataract development were also seen. One obligate carrier and several other family members had minor ocular anomalies, thus confounding the scoring of affected and unaffected individuals. Cerebral hemorrhages had occurred in 4 individuals, in 3 at birth or during the first year of life. Seven patients with corneal clouding were considered "definitely affected" for linkage studies. Haplotype mapping revealed that they shared a 14 cM region in the terminal part of chromosome 13q that included the locus for COL4A1. The affected family members were heterozygous for a novel COL4A1 sequence variant c.4881C>G (p.Asn1627Lys) predicted to be damaging and not found among 185 local blood donors. Exome sequencing showed that this variant was the only one in the candidate region not found in dbSNP.

CONCLUSION

Among the family members shown to carry the novel COL4A1 mutation, heterogenous presentations of anterior segment dysgenesis was seen. Testing family members for this mutation also made a definite diagnosis possible in patients with a clinical presentation difficult to classify. In families where anterior segment dysgenesis occurs together with cerebral hemorrhages, genetic analysis of COL4A1 should be considered.

Diagnosis and rehabilitation of visual field defects in stroke patients: a retrospective audit

OBJECTIVE

Visual field defects (VFD) after stroke can cause significant disability and reduction in quality of life. Adequate diagnosis of VFD and referral to visual rehabilitation are important to improve outcome. Our aim was to conduct a retrospective clinical audit to investigate how neurologists detect and follow up VFD in stroke patients in a university hospital in Norway.

METHODS

All patients registered in the Bergen NORSTROKE Registry from February 2006 to May 2009 with (1) occipital lobe infarctions and (2) non-occipital infarction and clinically detected VFD were included in the study. Their medical records were reviewed for referral to perimetry for examination of VFD and for referral to a visual rehabilitation program within the first year after brain injury.

RESULTS

Of 353 patients, 34 (9.6%) were referred to perimetry and 8 (2.3%) to visual rehabilitation. Patients referred to perimetry were younger (65.1 vs. 74.7 years, p < 0.001), had lower modified Rankin Scale scores (2.53 vs. 3.47, p = 0.003), and scored lower on the National Institutes of Health Stroke Scale upon admission (6.68 vs. 13.90, p < 0.001). Men were more often referred to perimetry than women (73.5 vs. 26.5%, p < 0.001), and those referred were younger (61.2 vs. 75.8 years, p = 0.03).

CONCLUSIONS

Only few patients were referred to perimetry, and even fewer were offered visual rehabilitation. Age and gender were negative predictors for referral. Neurologists' awareness of the significant disability related to VFD must be increased. Focused diagnostics on visual impairment and early referral to a visual rehabilitation program should be mandatory in stroke unit services.

Ciliopathies with skeletal anomalies and renal insufficiency due to mutations in the IFT-A gene WDR19

A subset of ciliopathies, including Sensenbrenner, Jeune, and short-rib polydactyly syndromes are characterized by skeletal anomalies accompanied by multiorgan defects such as chronic renal failure and retinitis pigmentosa. Through exome sequencing we identified compound heterozygous mutations in WDR19 in a Norwegian family with Sensenbrenner syndrome. In a Dutch family with the clinically overlapping Jeune syndrome, a homozygous missense mutation in the same gene was found. Both families displayed a nephronophthisis-like nephropathy. Independently, we also identified compound heterozygous WDR19 mutations by exome sequencing in a Moroccan family with isolated nephronophthisis. WDR19 encodes IFT144, a member of the intraflagellar transport (IFT) complex A that drives retrograde ciliary transport. We show that IFT144 is absent from the cilia of fibroblasts from one of the Sensenbrenner patients and that ciliary abundance and morphology is perturbed, demonstrating the ciliary pathogenesis. Our results suggest that isolated nephronophthisis, Jeune, and Sensenbrenner syndromes are clinically overlapping disorders that can result from a similar molecular cause.

A novel ADAMTSL4 mutation in autosomal recessive ectopia lentis et pupillae

PURPOSE

To examine the ocular malformations and identify the molecular genetic basis for autosomal recessive ectopia lentis et pupillae in five Norwegian families.

METHODS

Ten affected persons and 11 first-degree relatives of five Norwegian families underwent ophthalmic and general medical examination. Molecular genetic studies included homozygosity mapping with SNP markers, DNA sequencing, and RT-PCR analysis.

RESULTS

Ocular signs in affected persons were increased median corneal thickness and astigmatism, angle malformation with prominent iris processes, displacement of the pupil and lens, lens coloboma, spherophakia, loss of zonular threads, early cataract development, glaucoma, and retinal detachment. No cardiac or metabolic abnormalities known to be associated with ectopia lentis were detected. Affected persons shared a 0.67 cM region of homozygosity on chromosome 1. DNA sequencing revealed a novel mutation in ADAMTSL4, c.767_786del20. This deletion of 20 base pairs (bp) results in a frameshift and an introduction of a stop codon 113 bp downstream, predicting a C-terminal truncation of the ADAMTSL4 protein (p.Gln256ProfsX38). Expression of truncated ADAMTSL4 mRNA was confirmed by RT-PCR analysis. Three of 190 local blood donors were carriers of this mutation.

CONCLUSIONS

Ectopia lentis et pupillae is associated with a number of malformations primarily in the anterior segment of the eye. The causative mutation, which is the first to be described in ectopia lentis et pupillae, disrupts the same gene function previously shown to cause isolated ectopia lentis. The mutation is ancient and may, therefore, be spread to a much larger population than the investigated one.

Decorin accumulation contributes to the stromal opacities found in congenital stromal corneal dystrophy

PURPOSE

Congenital stromal corneal dystrophy (CSCD) is characterized by stromal opacities that morphologically are seen as interlamellar layers of amorphous substance with small filaments, the nature of which has hitherto been unknown. CSCD is associated with truncating mutations in the decorin gene (DCN). To understand the molecular basis for the corneal opacities we analyzed the expression of decorin in this disease, both at the morphologic and the molecular level.

METHODS

Corneal specimens were examined after contrast enhancement with cuprolinic blue and by immunoelectron microscopy. Decorin protein from corneal tissue and keratocyte culture was studied by immunoblot analysis before and after O- and N-deglycosylation. The relative level of DCN mRNA expression was examined using Q-RT-PCR, and cDNA was sequenced. Recombinant wild-type and truncated decorin transiently expressed in HEK293 cells were analyzed by gel filtration and immunoblotting.

RESULTS

The areas of interlamellar filaments were stained by cuprolinic blue. Immunoelectron microscopy using decorin antibodies revealed intense labeling of these areas. Both wild-type and truncated decorin protein was expressed in corneal tissue and keratocytes of affected persons. When decorin expressed in HEK293 cells was examined by gel filtration, the truncated decorin eluted as high molecular weight aggregates.

CONCLUSIONS

Accumulation of decorin was found in the interlamellar areas of amorphous substance. The truncated decorin is present in CSCD corneas, and there is evidence it may aggregate in vitro. Thus, decorin accumulation appears to contribute to the stromal opacities that are characteristic of CSCD.

Brittle cornea syndrome associated with a missense mutation in the zinc-finger 469 gene

PURPOSE

To investigate the diverse clinical manifestations, identify the causative mutation and explain the association with red hair in a family with brittle cornea syndrome (BCS).

METHODS

Eight family members in three generations underwent ophthalmic, dental, and general medical examinations, including radiologic examination of the spine. Bone mineral density (BMD) and serum levels of vitamin D, parathyroid hormone, and biochemical markers for bone turnover were measured. Skin biopsies were examined by light and transmission electron microscopy. Molecular genetic studies included homozygosity mapping with SNP markers, DNA sequencing, and MC1R genotyping.

RESULTS

At 42 and 48 years of age, respectively, both affected individuals were blind due to retinal detachment and secondary glaucoma. They had extremely thin and bulging corneas, velvety skin, chestnut colored hair, scoliosis, reduced BMD, dental anomalies, hearing loss, and minor cardiac defects. The morphologies of the skin biopsies were normal except that in some areas slightly thinner collagen fibrils were seen in one of the affected individuals. Molecular genetic analysis revealed a novel missense mutation of ZNF469, c.10016G>A, that was predicted to affect the fourth of the five zinc finger domains of ZNF469 by changing the first cysteine to a tyrosine (p.Cys3339Tyr). Both affected individuals were homozygous for the common red hair variant R151C at the MC1R locus.

CONCLUSIONS

BCS is a disorder that affects a variety of connective tissues. Reduced BMD and atypical dental crown morphology have not been reported previously. The results confirm that BCS is associated with mutations in ZNF469. The association with red hair in some individuals with BCS is likely to occur by chance.

Identification and characterization of two zebrafish nectin-1 genes that are differentially expressed in the developing eye and brain

Nectins are cell adhesion molecules of the immunoglobulin type that play important roles in the development of the nervous system. We have characterized two paralogous zebrafish nectin-1 genes, nectin-1a and nectin-1b, that differ in expression. Nectin-1a expression is first found in the anterior neural keel and later in the optic cup. In the retina, nectin-1a appears in the outer part and extends inwards, while nectin-1b starts in the inner part and spreads outwards. Only nectin-1a was detected in the cornea, the lens, and in the region of photoreceptor cell differentiation in the retina. Both genes were expressed in ganglion cells and inner nuclear neurons. In the brain, nectin-1a was restricted to the epiphysis and a cluster of cells in the posterior hindbrain, whereas nectin-1b was found in several brain areas. Zebrafish may, therefore, be a useful model for identifying different functions of nectin-1 in the developing eye and nervous system.

Gamma knife stereotactic radiosurgery of Nelson syndrome

OBJECTIVE

Gamma knife radiosurgery (GKR) can be used as primary or adjuvant therapy for the treatment of an ACTH-producing pituitary tumor after bilateral adrenalectomy, called Nelson syndrome (NS). We have examined the effect of GKR on tumor growth and ACTH-hypersecretion, and characterized the adverse events of this treatment in patients with NS.

DESIGN

Cross-sectional follow-up study. First, retrospective data pre- and post-GKR were collected. Patients then underwent a predefined survey including radiological, endocrinological, ophthalmological, and neurosurgical evaluation.

SUBJECTS

Ten patients treated with GKR for NS after previous bilateral adrenalectomy. The mean follow-up was 7 years. No patient was lost to follow-up.

RESULTS

Tumor growth was stopped in all patients. The ACTH levels declined in eight patients, and normalized in one patient. There was a significant drop in ACTH levels, with a half-time of 2.8 years. No patient developed visual field defects or any other cranial nerve dysfunction as a result of treatment. Four patients started hormone substitution therapy during the follow-up period. The substitution therapy of three pituitary axes present at GKR treatment could be stopped during the same period. One patient developed a glioblastoma in the left parieto-occipital region 14 years after GKR, far from the field of treatment. As the radiation level was below 1Gy to this area, it is unlikely that the GKR treatment itself induced the malignant tumor.

CONCLUSION

In patients with NS, GKR is an effective adjuvant treatment, carrying relatively few adverse effects. Although the risk of developing a secondary neoplasia after GKR is present, it is probably extremely low.

Gamma knife stereotactic radiosurgery for acromegaly

BACKGROUND

Gamma knife radiosurgery (GKR) is an adjuvant treatment for acromegaly if surgery fails to normalize GH hypersecretion.

OBJECTIVE

To examine the effect of GKR on tumor growth and hypersecretion, and to characterize the adverse effect of this treatment.

DESIGN

Cross-sectional follow-up study. First, retrospective data pre- and post-GKR were collected. PATIENTS then underwent a predefined survey including radiological, endocrinological, ophthalmological, and neurosurgical evaluation.

SETTING

Norwegian National Center for gamma knife treatment.

PATIENTS

Sixty-one patients treated with GKR for acromegaly. Out of 55, 53 living patients underwent a detailed survey. The mean follow-up was 5.5 years. No patient was lost to follow-up.

RESULTS

Tumor growth was stopped in all patients. At 3, 5, and 10 years after GKR, 45, 58, and 86% of patients had normal IGF-I levels. Consecutive hormone value analysis showed that patients receiving GH-suppressive medication had a more rapid decline in hypersecretion than those who did not receive such medication. Evaluated by survey baseline values alone, non-elevated IGF-I and GH levels below 5 mIU/l were found in 38%. GH-suppressive medication was terminated in 16 out of 40 patients following GKR. Nine out of 53 surveyed patients (17%) had normal IGF-I and GH nadir below 2.6 mIU/l at glucose tolerance tests, while not on hormone-suppressive medication. Two patients developed minor visual field defects. Eight patients started hormone substitution therapy during the follow-up period.

CONCLUSION

GKR is an effective adjuvant treatment for residual acromegaly, carrying few side effects.

A second decorin frame shift mutation in a family with congenital stromal corneal dystrophy

PURPOSE

To identify the genetic defect in a Belgian family with congenital stromal corneal dystrophy.

DESIGN

Case report and result of deoxyribonucleic acid (DNA) analyses.

METHODS

DNA sequencing of polymerase chain reaction (PCR) products generated from amplification of exons and adjacent introns of the decorin gene.

RESULTS

The family consisted of a mother and her son, both suffering from congenital stromal corneal dystrophy. In both individuals, a single base pair deletion (c.941delC) in the coding sequence of the decorin gene was demonstrated, predicting a C-terminal truncation of the decorin protein (p.Pro314fsX14).

CONCLUSION

This is the second family with congenital stromal corneal dystrophy of the cornea in which a frame shift mutation in the decorin gene has been detected. Both in this family and in a previously reported Norwegian family, a decorin protein missing the 33 C-terminal amino acids is predicted. This observation strongly supports a role for decorin in the pathogenesis of this disorder.

Chromosomal imbalances in a recurrent solitary fibrous tumor of the orbit

Using comparative genomic hybridization (CGH), array CGH, fluorescence in situ hybridization, and loss of heterozygosity analysis, we examined a recurrent solitary fibrous tumor of the orbit for chromosomal imbalances. In the primary tumor, loss of chromosomal material was observed at 9p, 9q, and 16q. In the first recurrent tumor, cells with these abnormalities were detected, but in some parts of the tumor, cells with losses at 13q (homozygous deletion at 13qter) and 20p were dominant. In the second recurrence, only cells with losses at 13q and 20p were seen. Although morphologically similar, the second recurrent tumor invaded the anterior cranial fossa and demonstrated considerably faster growth than the first recurrent tumor. Thus, the clone of tumor cells that dominated the second recurrent tumor was shown by cytogenetic analysis to be different from that present in the primary tumor, and was associated with a more aggressive nature of the tumor.

Chromosomal imbalances in some benign orbital tumours

PURPOSE

To examine benign orbital tumours for chromosomal imbalances.

METHODS

Specimens obtained from orbital tumours were screened for chromosomal imbalances using high resolution comparative genomic hybridization (CGH). The imbalances detected by CGH were confirmed by using fluorescence in situ hybridization (FISH) and loss of heterozygosity (LOH) analysis.

RESULTS

Chromosomal gains or losses were seen in 4/6 pleomorphic adenomas (gains at 8q; losses at 4p, 5p, 8p, 11p and 14q), 2/4 schwannomas (losses at 16p and 22q), and 1/9 cavernous haemangiomas (losses at 13q). Compared to previous studies of pleomorphic adenomas using G-band analysis, chromosomal imbalances were more frequently detected by using CGH. Gains of 8q11-q22 and losses of 4p15-pter, 11p12-p15, and 14q12-q23 in pleomorphic adenomas, losses of 16p12-p13 in schwannomas, and losses of 13q32-qter in cavernous haemangiomas have not been reported previously.

CONCLUSIONS

A range of chromosomal imbalances was detected even within tumours of the same histological subtype. We did not observe common chromosomal gains or losses that were characteristic for orbital presentation of the tumours. The clinical relevance of the abnormalities is uncertain, but they may indicate the position of genes that could play a role in tumour development.

Congenital Stromal Dystrophy of the Cornea Caused by a Mutation in the Decorin Gene

PURPOSE

To describe the clinical and pathologic characteristics of a family with a congenital stromal dystrophy of the cornea and to identify the genetic basis for this disorder.

METHODS

All family members in three generations underwent ophthalmic examination. Stored corneal buttons were examined by transmission electron microscopy. Molecular genetic studies, including a genome-wide scan with microsatellite markers, linkage analysis, and DNA sequencing, were performed.

RESULTS

The dystrophy was inherited in an autosomal dominant pattern and was seen as clouded corneas shortly after birth. No associated systemic abnormalities or congenital diseases were present. After penetrating keratoplasty (PK), the grafts remained completely clear in 56% of the eyes with a mean (range) observation period of 19.5 years (3-36). Transmission electron microscopy of corneal buttons revealed lamellae with normal arrangement of collagen fibrils separated by abnormal fibrillar layers. Genome-wide screening revealed linkage to chromosome 12q22, with a maximum LOD score of 4.68 at D12S351. Subsequent sequencing of candidate genes revealed a frameshift mutation in the DCN gene (c.967delT) that encodes for decorin, predicting a C-terminal truncation of the decorin protein (p.S323fsX5).

CONCLUSIONS

The authors hypothesize that truncated decorin binds to collagen in a suboptimal way, disturbing the regularity of corneal collagen fibril formation and thereby causing corneal opacities. To the best of the authors' knowledge, this is the first description of a disorder associated with an inherited alteration in the decorin gene in humans.

Expression of 5'-nucleotidase and alkaline phosphatase in human aqueous drainage channels

PURPOSE

Lymphatic vessels and blood vessels can be distinguished histochemically by their expression of 5'-nucleotidase and alkaline phosphatase. The aim of this study was to compare the expression of these enzymes in human aqueous drainage channels with that seen in lymphatics and blood vessels.

METHODS

Histological sections from the angular regions of human eyes were prepared both by enzyme histochemical and immunohistochemical methods to analyse 5'-nucleotidase and alkaline phosphatase expression. In some of these eyes, Indian ink-stained gelatin was injected into Schlemm's canal and the suprachoroidal space to facilitate the identification of aqueous drainage routes.

RESULTS

There was no expression of 5'-nucleotidase in the endothelium of aqueous drainage channels. Ocular blood vessels were characterized by strong expression of alkaline phosphatase, whereas the cellular lining of Schlemm's canal, the collector channels, the aqueous veins and a scleral channel from the suprachoroidal space showed significantly weaker expression or no expression at all.

CONCLUSION

The study failed to show a histochemical similarity between lymphatics and human aqueous drainage channels, as no expression of 5'-nucleotidase could be found in any part of the aqueous outflow pathway. The endothelium of aqueous drainage channels also differed from normal blood vessels by a much weaker expression of alkaline phosphatase. This makes a histochemical distinction between aqueous veins and scleral veins possible.

Chromosomal imbalances in lymphoid tumors of the orbit

PURPOSE

To identify chromosomal gains and losses in lymphoid tumors of the orbit and to examine whether such abnormalities are related to orbital presentation, disease severity, or risk for recurrent disease.

METHODS

Biopsy specimens from 26 patients were examined by histomorphologic and immunohistochemical analysis. Lymphomas were classified according to the Revised European-American Lymphoma Classification. Chromosomal imbalances were detected by high-resolution comparative genomic hybridization (CGH). Clinical data were obtained by retrospective evaluation of medical records.

RESULTS

Chromosomal imbalances were detected in 0 of 6 patients with idiopathic orbital inflammation, 0 of 2 with benign reactive lymphoid hyperplasia, 3 of 3 with highly malignant diffuse large B-cell lymphoma, 4 of 10 with marginal zone B-cell lymphoma, 0 of 1 with chronic lymphatic leukemia lymphoma, and 1 of 4 with immunocytoma. Among the low-grade malignancies, chromosomal imbalances were seen in 1 of 9 at stage IAE, 2 of 3 at stage IIE, and 2 of 3 at stage IVE. Chromosomal imbalances were observed in all primary tumors from the five patients that later developed recurrent disease. In 14 of 23 imbalances with intrachromosomal breaks outside the centromere region, the breaks were present at bands with known fragile sites. No chromosomal imbalances specific for orbital presentation were detected.

CONCLUSIONS

Chromosomal imbalances were seen mainly in orbital lymphomas that were either highly malignant or at an advanced stage. CGH analysis of orbital lymphomas could be prognostically relevant, but further studies are required to confirm this notion.

Transcription from the gene encoding the herpesvirus entry receptor nectin-1 (HveC) in nervous tissue of adult mouse

Both human and murine forms of nectin-1 (HveC, Prr1) can serve as entry receptors for several neurotropic herpesviruses, including herpes simplex viruses 1 and 2 (HSV-1, HSV-2), porcine pseudorabies virus (PRV), and bovine herpesvirus 1. HSV-1, HSV-2, and PRV can cause lethal neurological disease in mice whether inoculation is directly into the central nervous system or by peripheral routes. Expression of nectin-1 transcripts in cells of the adult mouse nervous system was assessed by in situ hybridization. Specific hybridization signals were detected in neurons in sensory, sympathetic, and parasympathetic ganglia of the peripheral nervous system. In addition, specific signals were observed in neurons of the ventral and dorsal horns of the spinal cord and of the brain stem, cerebellum, cerebral cortex, hippocampus, dentate gyrus, and olfactory bulb. These results show that the nectin-1 gene is widely transcribed in neurons in adult mouse. Nectin-1 is the only known receptor capable of mediating the entry of all three viruses, HSV-1, HSV-2, and PRV. Its pattern of expression in the nervous system suggests a key role in neurological disease caused by these viruses.