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Supplemental Digital Content is Available in the Text., Purpose: This study aims to clinically and genetically report a case of coexisting Meesmann corneal dystrophy (MECD) and pseudo-unilateral lattice corneal dystrophy (LCD). Methods: Clinical characterization was supported by a complete ophthalmological evaluation, including visual acuity measurement and slit-lamp examination. Molecular diagnosis was performed by whole-exome sequencing analyzing the gelsolin, keratin K3 (KRT3), keratin K12, and transforming growth factor-beta–induced genes. Results: A 57-year-old woman presented with recurrent corneal erosions over 17 years and visual impairment in both eyes. Ophthalmological evaluation revealed multiple central tiny cysts in the epithelium of both eyes and lattice linear lesions only in the right cornea. In both eyes, a corneal posterior crocodile shagreen degeneration could also be observed. These findings were compatible with a MECD and a unilateral LCD. Molecular analysis identified the novel heterozygous nucleotide substitution c.1492G>A (amino acid change p.Glu498Lys) in the KRT3 gene, in cosegregation with the MECD familial phenotype. However, no genetic evidence supported the unique LCD phenotype observed in the patient. Conclusions: To the best of our knowledge, this is the first report of a pseudo-unilateral LCD in a patient with coexistent MECD. Moreover, the genetic analysis showed a novel mutation in the previously MECD-associated gene KRT3.

IMPORTANCE Rare transforming growth factor beta-induced (TGFBI) gene variants are involved in autosomal dominant corneal dystrophies (CDs) with heterogeneous clinical features. BACKGROUND The purpose of this study was to analyse TGFBI gene variants and genotype-phenotype correlations in a cohort affected by atypical stromal CD. DESIGN Retrospective cohort study (from May 2014 to September 2017). PARTICIPANTS Thirty-five individuals from 10 unrelated South European families presenting atypical lattice CD (LCD) were included. METHODS Corneal phenotypes were assessed by slit-lamp examination and optical coherence tomography (OCT). Contrast sensitivity was measured under mesopic conditions. Genomic DNA was obtained from blood samples, and all 17 TGFBI exons were screened for variants by Sanger sequencing. MAIN OUTCOME MEASURES p.(L558P) variant of TGFBI gene. RESULTS The p.(L558P) variant was identified in 22 members of the 10 families diagnosed with atypical LCD, characterized by late-onset and absence of recurrent erosion syndrome. OCT revealed punctiform deposits in the deep-mid stroma and normal anterior stroma. This variant was demonstrated to be transmitted with the disease according to autosomal dominant inheritance in most families. CONCLUSIONS AND RELEVANCE To the best of our knowledge, we describe a detailed clinical characterization of the largest CD cohort carrying the TGFBI p.(L558P) variant. We propose that the atypical phenotype of this recently reported alteration can be classified as a form of LCD type IV. The results show that OCT and anterior-posterior analysis of the stromal location of the opacities, along with a genetic analysis of TGFBI, are required to ensure accurate diagnosis and management of CDs.

Background: To evaluate the distribution of the transforming growth factor-beta induced (TGFBI) corneal dystrophies in a multi-ethnic population in Singapore, and to present the different phenotypes with the same genotype. Methods: This study included 32 patients. Slit lamp biomicroscopy was performed for each patient to determine the disease phenotype. Genomic DNA was extracted from the blood samples and the 17 exons of the TGFBI gene were amplified by PCR and sequenced bi-directionally for genotype analysis. Results: Regarding phenotypes, the study patients comprised 11 (34.4%, 8 with R555W and 3 with R124H mutation) patients with granular corneal dystrophy type 1 (GCD1), 6 (18.8%, 5 with R124H and 1 with R124C mutation) patients with GCD2, 13 (40.6%, 7 with R124C, 2 with H626R, 2 with L550P, 1 with A620D and 1 with H572R) patients with lattice corneal dystrophy (LCD) and 2 (6.3%, 1 with R124L and 1 with R124C) patients with Reis&ndash, B&uuml, ckler corneal dystrophy. Regarding genotype, R124H mutation was associated with GCD2 (5 cases, 62.5%) and GCD1 (3 cases, 37.5%). R124C mutation was associated with LCD (7 cases, 87.5%) and GCD2 (1 case, 12.5%). All the 8 cases (100%) of R555W mutation were associated with GCD1. Conclusions: Although the association between genotype and phenotype was good in most cases (65.7%, 21 of 32 patients), genotype/phenotype discrepancy was observed in a significant number.

Simple Summary Gelsolin amyloidosis is a rare autosomal dominant genetic disease, which typically affects the cornea, skin and sometimes other organ systems and is caused by mutations in a gene coding for gelsolin protein (GSN). We describe a novel mutation of GSN gene, p.Glu580Lys, associated with gelsolin amyloidosis in six members of a two-generation family, who exhibited lattice corneal dystrophy, loose facial skin and irregular heart rhythm. In one patient we reported optic nerve impairment, which is possibly a novel feature associated with gelsolin amyloidosis. Abstract Gelsolin amyloidosis typically presents with corneal lattice dystrophy and is most frequently associated with pathogenic GSN variant p.Asp214Asn. Here we report clinical and histopathological features of gelsolin amyloidosis associated with a novel GSN variant p.Glu580Lys. We studied DNA samples of seven members of a two-generation family. Exome sequencing was performed in the proband, and targeted Sanger sequencing in the others. The heterozygous GSN variant p.Glu580Lys was identified in six patients. The patients exhibited corneal dystrophy (5/6), loose skin (5/6) and/or heart arrhythmia (3/6) and one presented with bilateral optic neuropathy. The impact of the mutation on the protein structure was evaluated in silico. The substitution is located in the fifth domain of gelsolin protein, homologous to the second domain harboring the most common pathogenic variant p.Asp214Asn. Structural investigation revealed that the mutation might affect protein folding. Histopathological analysis showed amyloid deposits in the skin. The p.Glu580Lys is associated with corneal dystrophy, strengthening the association of the fifth domain of gelsolin protein with the typical amyloidosis phenotype. Furthermore, optic neuropathy may be related to the disease and is essential to identify before discussing corneal transplantation.

Transforming growth factor-β-induced protein (TGFBIp), an extracellular matrix protein, is the second most abundant protein in the corneal stroma. In this review, we summarize the current knowledge concerning the expression, molecular structure, binding partners, and functions of human TGFBIp. To date, 74 mutations in the transforming growth factor-β-induced gene (TGFBI) are associated with amyloid and amorphous protein deposition in TGFBI-linked corneal dystrophies. We discuss the current understanding of the biochemical mechanisms of TGFBI-linked corneal dystrophies and propose that mutations leading to granular corneal dystrophy (GCD) decrease the solubility of TGFBIp and affect the interactions between TGFBIp and components of the corneal stroma, whereas mutations associated with lattice corneal dystrophy (LCD) lead to a destabilization of the protein that disrupts proteolytic turnover, especially by the serine protease HtrA1. Future research should focus on TGFBIp function in the cornea, confirmation of the biochemical mechanisms in vivo, and the development of disease models. Future therapies for TGFBI-linked corneal dystrophies might include topical agents that regulate protein aggregation or gene therapy that targets the mutant allele by CRISPR/Cas9 technology.

Purpose: The purpose of this study is to evaluate the outcomes of keratoplasty for lattice corneal dystrophy (LCD) performed at a tertiary eye care center. Methods: A retrospective review of medical records of those patients who were clinically diagnosed to have LCD (72 eyes of 57 patients) and underwent either penetrating keratoplasty (PK, 58 eyes of 46 patients) or deep anterior lamellar keratoplasty (DALK, 14 eyes of 13 patients) between the years 1987 and 2014 was performed. The main outcome measures included demographics, clinical features, and outcomes of keratoplasty. Results: The median follow-up after keratoplasty was 3.1 years (interquartile range [IQR], 9 months to 9 years). The median best-corrected visual acuity (BCVA) was 0.18 (IQR, 0.10–0.48) (Snellen equivalent 20/30 [IQR, 20/25–20/60]) at 4 years postoperatively and 0.65 (IQR, 0.18-0.95) (Snellen equivalent 20/89 [IQR, 20/30–20/178]) at 10 years following surgery. DALK eyes had a significantly better BCVA than PK eyes at 2 years following keratoplasty. The median overall survival of grafts was 15.8 years. Late complications included recurrence of LCD (14 eyes), graft infiltrate (23 eyes), graft rejection (15 eyes), graft failure (16 eyes), and glaucoma (14 eyes). Conclusion: The outcomes of graft are similar following PK and deep anterior lamellar keratoplasty; however, the latter appears to provide slightly better visual outcome. Recurrence of dystrophy in the graft and graft infiltrates limit the overall graft survival in both the groups.

Purpose To determine the prevalence of the transforming growth factor (TGF) β–induced gene corneal dystrophies in refractive surgery candidates in China. Setting Five hospitals in China. Design Prospective case series. Method Refractive surgical candidates from 5 preselected eye hospitals/centers in China were recruited after providing informed consent. All patients had slitlamp biomicroscopy and collection of a buccal swab as a source of DNA for screening of the TGF β–induced gene for the 5 most common mutations associated with Reis-Buckler corneal dystrophy, Thiel-Behnke corneal dystrophy, granular corneal dystrophy type 1, granular corneal dystrophy type 2, and lattice corneal dystrophy type 1. Results Of the 2068 refractive surgery candidates analyzed, 4 had corneal opacities in both eyes on slitlamp examination. Screening for the TGF β–induced gene found the heterozygous p.R124H mutation associated with granular corneal dystrophy type 2 in each of the 4 individuals with corneal opacities as well as in a fifth individual who did not have any corneal opacities, for a prevalence of 0.24%. Exacerbation of dystrophic corneal deposition developed after laser refractive surgery in 2 individuals who did not have preoperative TGF β–induced gene screening. Conclusions The prevalence of the TGF β–induced gene corneal dystrophies in Chinese refractive surgery candidates was estimated to be approximately 0.24%. Genetic testing is recommended to identify and exclude from candidacy all individuals with a TGF β–induced gene dystrophy before elective keratorefractive surgery to avoid causing accelerated postoperative dystrophic deposition.

TGFBI-associated corneal dystrophies are inherited disorders caused by TGFBI gene variants that promote deposition of mutant protein (TGFBIp) as insoluble aggregates in the cornea. Depending on the type and position of amino acid substitution, the aggregates may be amyloid fibrillar, amorphous globular or both, but the molecular mechanisms that drive these different patterns of aggregation are not fully understood. In the current study, we report the protein composition of amyloid corneal aggregates from lattice corneal dystrophy patients of Asian origin with H626R and R124C mutation and compared it with healthy corneal tissues via LC-MS/MS. We identified several amyloidogenic, nonfibrillar amyloid associated proteins and TGFBIp as the major components of the deposits. Our data indicates that apolipoprotein A-IV, apolipoprotein E, and serine protease HTRA1 were significantly enriched in patient deposits compared to healthy controls. HTRA1 was also found to be 7-fold enriched in the amyloid deposits of patients compared to the controls. Peptides sequences (G

Background: Unilateral lattice corneal dystrophy is a rare entity. Objective: To highlight the evidence of unilateral lattice corneal dystrophy in a young female. Case : A young 28 years old female presented to the outpatient department of Ophthalmology with slowly progressive diminution of vision in left eye for one month. On ophthalmological examination best corrected visual acuity (BCVA) was 20/20 and 20/40 with refractive error of plano and -0.75D Cyl @30 for right and left eye respectively. Ocular examination of right eye was unremarkable. On slit lamp examination, left eye showed multiple radial lattice lines in branching spider like pattern in the temporal cornea with pupillary margin involvement. The lattice pattern was confined to anterior to midstroma of the cornea with intact epithelium and unremarkable endothelium. The lesions did not involve the limbus. These lattice lines were prominent on retroillumination. In temporal quadrant near pupillary margin a small radial nebulomacular corneal opacity was seen without any corneal vascularisation or edema. The anterior chamber was deep and quiet. Corneal sensations were markedly reduced. Intraocular pressure was 10 and 12mmHg for right and left eye respectively with noncontact tonometry. Fundus examination was unremarkable. Family history and systemic history was negative. Optical coherence tomography(OCT) showed hyperreflective material in midstoma confirmed the diagnosis of unilateral lattice corneal dystrophy(LCD) with an apparently healthy fellow eye .

Corneal stromal dystrophies are a group of genetic disorders that may be caused by mutations in the transforming growth factor β-induced (TGFBI) gene which results in the aggregation and deposition of mutant proteins in various layers of the cornea. The type of amino acid substitution dictates the age of onset, anatomical location of the deposits, morphological features of deposits (amyloid, amorphous powder or a mixture of both forms) and the severity of disease presentation. It has been suggested that abnormal turnover and aberrant proteolytic processing of the mutant proteins result in the accumulation of insoluble protein deposits. Using mass spectrometry, we identified increased abundance of a 32 amino acid-long peptide in the 4th fasciclin-like domain-1 (FAS-1) domain of transforming growth factor β-induced protein (amino acid 611–642) in the amyloid deposits of the patients with lattice corneal dystrophies (LCD). In vitro studies demonstrated that the peptide readily formed amyloid fibrils under physiological conditions. Clinically relevant substitution (M619K, N622K, N622H, G623R and H626R) of the truncated peptide resulted in profound changes in the kinetics of amyloid formation, thermal stability of the amyloid fibrils and cytotoxicity of fibrillar aggregates, depending on the position and the type of the amino acid substitution. The results suggest that reduction in the overall net charge, nature and position of cationic residue substitution determines the amyloid aggregation propensity and thermal stability of amyloid fibrils.

The aim of the present study was to examine the clinical features of three Chinese families with autosomal dominant corneal dystrophy (CD) and examine transforming growth factor‑β‑induced (TGFBI) gene mutations in these families. The TGFBI gene mutations were detected using direct sequencing of the whole coding regions and exon-intron boundaries of the TGFBI gene in the affected members from the three families with CD. The phenotypes of all affected individuals in the three families were observed via slit lamp examination. Sections of the cornea were used for biopsy following keratoplasty. Three types of TGFBI gene mutations, R124C, H626R and R124H, were detected in the patients from these three families. One family, with the R124C mutation, was diagnosed with lattice corneal dystrophy type 1, and the family with the H626R mutation was diagnosed with lattice corneal dystrophy type IIIB. The family with the R124H mutation was diagnosed with granular corneal dystrophy type 2. The TGFBI gene mutations were considered underlying factors in the molecular mechanism underlying the pathogenesis of cornea dystrophy. Therefore, the detection of TGFBI gene mutations may be useful in the differential diagnosis of CD.

Mutations in transforming growth factor-beta-induced (TGFBI) gene cause clinically distinct types of corneal dystrophies. To delineate the mechanisms driving these dystrophies, we focused on the R124C mutation in TGFBI that causes lattice corneal dystrophy type1 (LCD1) and generated novel transgenic mice harbouring a single amino acid substitution of arginine 124 with cysteine in TGFBI via ssODN-mediated base-pair substitution using CRISPR/Cas9 technology. Eighty percent of homozygous and 9.1% of heterozygous TGFBI-R124C mice developed a corneal opacity at 40 weeks of age. Hematoxylin and eosin and Masson trichrome staining showed eosinophilic deposits in subepithelial corneal stroma that stained negative for Congo-red. Although amyloid deposition was not observed in TGFBI-R124C mice, irregular amorphous deposits were clearly observed via transmission electron microscopy near the basement membrane. Interestingly, we found that the corneal deposition of TGFBI protein (TGFBIp) was significantly increased in homozygous TGFBI-R124C mice, suggesting a pathogenic role for the mutant protein accumulation. Furthermore, as observed in the LCD1 patients, corneal epithelial wound healing was significantly delayed in TGFBI-R124C mice. In conclusion, our novel mouse model of TGFBI-R124C corneal dystrophy reproduces features of the human disease. This mouse model will help delineate the pathogenic mechanisms of human corneal dystrophy.

Purpose Corneal dystrophies (CD) are classified as rare eye diseases that results in visual impairment and requires corneal transplant in advanced stages. Ocular surface inflammatory status in different types of CD remains underexplored. Hence, we studied the levels of tear soluble factors in the tears of patients with various types of corneal dystrophies. Methods 17 healthy subjects and 30 CD subjects (including epithelial, stromal and endothelial CD) were included in the study. Schirmer's strips were used to collect the tear fluid in all subjects. 27 soluble factors including cytokines, chemokines, soluble cell adhesion molecules and growth factors were measured in the eluted tears by multiplex ELISA or single analyte sandwich ELISA. Results Percentages of subjects with detectable levels of tear soluble factors were significantly higher in CD compared to controls. Significant higher level of IL-2 was observed in both epithelial and stromal CD. IL-4, TGFβ1 and IgE were significantly higher in stromal CD. VCAM, IL-13 and Fractalkine were significantly elevated in epithelial and macular CD. IL-1α, IL-8, IL-12, ANG, Eotaxin, MCP1, RANTES, ICAM1, L-selectin and P-selectin were significantly higher in epithelial CD. TGFBIp was significantly elevated in lattice CD and endothelial CD. Conclusion Distinct set of the tear soluble factors were dysregulated in various types of CD. Increase in tear inflammatory factors was observed in majority of the CD subjects depending on their sub-types. This suggests a plausible role of aberrant inflammation in CD pathobiology. Hence, modulating inflammation could be a potential strategy in improving the prognosis of CD.

JBC papers in press 297(1), 100858 (2021). doi:10.1016/j.jbc.2021.100858, Protein aggregation in the outermost layers of the cornea, which can lead to cloudy vision and in severe cases blindness, is linked to mutations in the extracellular matrix protein transforming growth factor-β–induced protein (TGFBIp). Among the most frequent pathogenic mutations are R124H and R555W, both associated with granular corneal dystrophy (GCD) characterized by the early-onset formation of amorphous aggregates. The molecular mechanisms of protein aggregation in GCD are largely unknown. In this study, we determined the crystal structures of R124H, R555W, and the lattice corneal dystrophy-associated A546T. Although there were no changes in the monomeric TGFBIp structure of any mutant that would explain their propensity to aggregate, R124H and R555W demonstrated a new dimer interface in the crystal packing, which is not present in wildtype TGFBIp or A546T. This interface, as seen in both the R124H and R555W structures, involves residue 124 of the first TGFBIp molecule and 555 in the second. The interface is not permitted by the Arg124 and Arg555 residues of wildtype TGFBIp and may play a central role in the aggregation exhibited by R124H and R555W in vivo. Using cross-linking mass spectrometry and in-line size exclusion chromatography–small-angle X-ray scattering, we characterized a dimer formed by wildtype and mutant TGFBIps in solution. Dimerization in solution also involves interactions between the N- and C-terminal domains of two TGFBIp molecules but was not identical to the crystal packing dimerization. TGFBIp-targeted interventions that disrupt the R124H/R555W crystal packing dimer interface might offer new therapeutic opportunities to treat patients with GCD., Published by American Soc. for Biochemistry and Molecular Biology, Bethesda, MD.

Mutations in the BIGH3 gene encoding for keratoepithelin protein have been described in different corneal dystrophies viz. granular corneal dystrophy, lattice corneal dystrophy, and their different clinical subtypes. Even though linked to the BIGH3 gene, the role of BIGH3 gene in the pathogenesis of corneal lattice dystrophy and corneal granular dystrophy remains to be elucidated. We describe the probable functions of a mutated BIGH3 gene in disease pathogenesis, postulate the existence of other phenotype modifier mutations in these dystrophies, and how the coinheritance of these mutations in different combinations along with a normal/mutated BIGH3 gene can lead to the different morphologic patterns seen in these corneal dystrophies and their subtypes.

Background/Aims To report the clinical, histopathological and genetic features of a variant of lattice corneal dystrophy (LCD) associated with two pathogenic mutations in the transforming growth factor-B-induced ( TGFBI ) gene. Methods Clinical characterisation was performed by slit lamp examination and in vivo confocal microscopic imaging (IVCM). Histopathological characterisation was performed with light microscopic examination of an excised corneal button and a peripheral blood samples were collected for TGFBI screening. Results A 42-year-old woman presented with progressive photophobia and decreased visual acuity in both eyes. Slit lamp examination demonstrated punctate and linear branching opacities in the mid and posterior corneal stroma, corresponding to hyper-reflective opacities noted on IVCM and amyloid deposition noted on histopathological examination of an excised corneal button. TGFBI screening revealed two previously reported heterozygous missense mutations: c.337G>A (p.(Val113Ile)) in exon 4 and c.1673T>C (p.(Leu558Pro)) in exon 12. Screening of an affected sibling with a similar phenotype revealed that she was also heterozygous for both mutations, while screening of another sibling with punctate but not linear stromal opacities revealed that she was heterozygous for only the p.(Leu558Pro) mutation. Conclusions The p.(Val113Ile) mutation results in an alteration of the atypical LCD phenotype associated with the p.(Leu558Pro) mutation. This represents only the second report of the alteration of the phenotype of a TGFBI dystrophy by a second, non-homozygous pathogenic mutation, and thus provides insight into the phenotype-genotype correlation of the TGFBI dystrophies.

To identify transforming growth factor beta-induced (TGFBI) gene mutations in four Chinese families affected by corneal dystrophies.In this study, three families (21 patients and 18 normal relatives), respectively, with Reis-Bücklers corneal dystrophy (RBCD), classic lattice corneal dystrophy (LCDI), and variant LCD (LCDI/IIIA) were assessed. All subjects underwent a complete ophthalmological evaluation, including biomicroscopic inspection and dilated fundus examination. As a control, 100 individuals without corneal disease were selected from the general population. Polymerase chain reaction (PCR) and direct sequencing were used to screen for mutations in TGFBI.For the three families, a single heterozygous c.371GT (R124L) point mutation was found in exon 4 of TGFBI in 14 affected members with RBCD, a single heterozygous c.370CT (R124C) point mutation was found in exon 4 of TGFBI in four affected members with LCDI, and a single heterozygous c.1877AG (H626R) point mutation was found in exon 14 of TGFBI in four affected members with LCDI/IIIA. TGFBI gene mutation had not been detected in the unaffected members and 100 normal controls.TGFBI gene mutations were present in all three Chinese families with corneal dystrophy, and our study further verified the relationship between phenotype and genotype of corneal dystrophy.

Finnish type of hereditary gelsolin amyloidosis (FGA) is one of the most common diseases of Finnish disease heritage. Existing FGA knowledge is based only on smaller patient series, so our aim was to elucidate the natural course of the disease in a comprehensive sample of patients and to build up a national FGA patient registry.An inquiry about the known and suspected signs of FGA, sent to the members of Finnish Amyloidosis Association, telephone contacts, and hospital records were utilized to create the registry.A total of 227 patients were entered to the database. The first symptom was ophthalmological for 167 patients (73.6%) at the mean age of 39 years. Corneal lattice dystrophy (CLD) was reported at the mean age of 43 years. Impaired vision, polyneuropathy, facial nerve paresis, and cutis laxa appeared on average between 52 and 57 years. Carpal tunnel syndrome (CTS) was reported by 86 patients (37.9%). Nine patients (4.0%) had a pacemaker, and 12 (6.1%) had cardiomyopathy.The first symptom was ophthalmological in most cases. Except for CLD no prominent difference in the age of appearance was found between the major symptoms. CTS, cardiac pacemakers, and cardiomyopathy were remarkably more common compared to the general population.

Mutations in the transforming growth factor beta-induced (TGFBI) gene result in a group of hereditary diseases of the cornea that are collectively known as TGFBI corneal dystrophies. These mutations translate into amino acid substitutions mainly within the fourth fasciclin 1 domain (FAS1-4) of the transforming growth factor beta-induced protein (TGFBIp) and cause either amyloid or non-amyloid protein aggregates in the anterior and central parts of the cornea, depending on the mutation. The A546T substitution in TGFBIp causes lattice corneal dystrophy (LCD), which manifests as amyloid-type aggregates in the corneal stroma. We previously showed that the A546T substitution renders TGFBIp and the FAS1-4 domain thermodynamically less stable compared with the wild-type (WT) protein, and the mutant FAS1-4 is prone to amyloid formation in vitro. In the present study, we identified the core of A546T FAS1-4 amyloid fibrils. Significantly, we identified the Y571-R588 region of TGFBIp, which we previously found to be enriched in amyloid deposits in LCD patients. We further found that the Y571-R588 peptide seeded fibrillation of A546T FAS1-4 and, more importantly, we demonstrated that native TGFBIp aggregates in the presence of fibrils formed by the core peptide. Collectively, these data suggest an involvement of the Y571-R588 peptide in LCD pathophysiology.

To update the 2008 International Classification of Corneal Dystrophies (IC3D) incorporating new clinical, histopathologic, and genetic information.The IC3D reviewed worldwide peer-reviewed articles for new information on corneal dystrophies published between 2008 and 2014. Using this information, corneal dystrophy templates and anatomic classification were updated. New clinical, histopathologic, and confocal photographs were added.On the basis of revisiting the cellular origin of corneal dystrophy, a modified anatomic classification is proposed consisting of (1) epithelial and subepithelial dystrophies, (2) epithelial-stromal TGFBI dystrophies, (3) stromal dystrophies, and (4) endothelial dystrophies. Most of the dystrophy templates are updated. The entity "Epithelial recurrent erosion dystrophies" actually includes a number of potentially distinct epithelial dystrophies (Franceschetti corneal dystrophy, Dystrophia Smolandiensis, and Dystrophia Helsinglandica) but must be differentiated from dystrophies such as TGFBI-induced dystrophies, which are also often associated with recurrent epithelial erosions. The chromosome locus of Thiel-Behnke corneal dystrophy is only located on 5q31. The entity previously designated as a variant of Thiel-Behnke corneal dystrophy on chromosome 10q24 may represent a novel corneal dystrophy. Congenital hereditary endothelial dystrophy (CHED, formerly CHED2) is most likely only an autosomal recessive disorder. The so-called autosomal dominant inherited CHED (formerly CHED1) is insufficiently distinct to continue to be considered a unique corneal dystrophy. On review of almost all of the published cases, the description appeared most similar to a type of posterior polymorphous corneal dystrophy linked to the same chromosome 20 locus (PPCD1). Confocal microscopy also has emerged as a helpful tool to reveal in vivo features of several corneal dystrophies that previously required histopathologic examination to definitively diagnose.This revision of the IC3D classification includes an updated anatomic classification of corneal dystrophies more accurately classifying TGFBI dystrophies that affect multiple layers rather than are confined to one corneal layer. Typical histopathologic and confocal images have been added to the corneal dystrophy templates.

Corneal dystrophies are a group of inherited disorders localized to various layers of the cornea that affect corneal transparency and visual acuity. The deposition of insoluble protein materials in the form of extracellular deposits or intracellular cysts is pathognomic. Mutations in TGFBI are responsible for superficial and stromal corneal dystrophies. The gene product, transforming growth factor β induced protein (TGFBIp) accumulates as insoluble deposits in various forms. The severity, clinicopathogenic variations, age of the onset, and location of the deposits depend on the type of amino acid alterations in the protein. Until 2006, 38 different pathogenic mutants were reported for the TGFBI-associated corneal dystrophies. This number has increased to 63 mutants, reported in more than 30 countries. There is no effective treatment to prevent, halt, or reverse the deposition of TGFBIp. This review presents a complete mutation update, classification of phenotypes, comprehensive reported incidents of various mutations, and current treatment options and their shortcomings. Future research directions and possible approaches to inhibiting disease progression are discussed.

PURPOSE To evaluate the question whether lattice corneal dystrophy type 1 (LCD1) is of epithelial or stromal origin. METHODS The landmark of advanced LCD1 shows central superficial haze and paracentral stromal lattice lines. In 16 eyes of 8 affected individuals of 2 families, a penetrating keratoplasty was performed. The follow-up was 8 to 16 years after penetrating keratoplasty. Slit-lamp documentation of the patients was evaluated in direct and indirect illumination with dilated pupil to assess the horizontal and vertical pattern of new deposits on the corneal graft. Three affected patients of 2 families are demonstrated in detail. A DNA analysis was performed. RESULTS Gene identification revealed a transforming growth factor beta-induced (TGFBI) Leu509Pro mutation in the first family, and a TGFBI Arg124Cys mutation in the second family. The demonstrated 5 corneal grafts of the 3 LCD1-patients showed diffuse opacities of distinct severity, beginning 3 to 4 years postoperatively, that were often combined with corneal erosions and consecutive pain. In none of our patients, we were able to detect any signs of lattice formation in the form of gray lines that run obliquely from the surface to the midstroma in direct illumination. In retroillumination, no lattice opacity units in the form of translucent and refractile lines were visible on the graft. CONCLUSIONS The TGFBI gene, that is responsible for LCD1, is expressed above all by the corneal epithelial cells but also by the keratocytes. We interpret the superficial diffuse LCD1 recurrences on the graft as the product of the epithelial cells, whereas the nonoccurrence of lattice lines as long as 18 years after keratoplasty, an indirect sign that the lattice lines are the product of the keratocytes. Thus, LCD1 seems to represent an epithelial-stromal entity, because both epithelial cells and keratocytes are involved.

The purpose of this study is to evaluate the outcomes of keratoplasty for lattice corneal dystrophy (LCD) performed at a tertiary eye care center.A retrospective review of medical records of those patients who were clinically diagnosed to have LCD (72 eyes of 57 patients) and underwent either penetrating keratoplasty (PK, 58 eyes of 46 patients) or deep anterior lamellar keratoplasty (DALK, 14 eyes of 13 patients) between the years 1987 and 2014 was performed. The main outcome measures included demographics, clinical features, and outcomes of keratoplasty.The median follow-up after keratoplasty was 3.1 years (interquartile range [IQR], 9 months to 9 years). The median best-corrected visual acuity (BCVA) was 0.18 (IQR, 0.10-0.48) (Snellen equivalent 20/30 [IQR, 20/25-20/60]) at 4 years postoperatively and 0.65 (IQR, 0.18-0.95) (Snellen equivalent 20/89 [IQR, 20/30-20/178]) at 10 years following surgery. DALK eyes had a significantly better BCVA than PK eyes at 2 years following keratoplasty. The median overall survival of grafts was 15.8 years. Late complications included recurrence of LCD (14 eyes), graft infiltrate (23 eyes), graft rejection (15 eyes), graft failure (16 eyes), and glaucoma (14 eyes).The outcomes of graft are similar following PK and deep anterior lamellar keratoplasty; however, the latter appears to provide slightly better visual outcome. Recurrence of dystrophy in the graft and graft infiltrates limit the overall graft survival in both the groups.

Purpose: The majority of anterior corneal dystrophies are caused by dominant mutations in TGFBI (transforming growth factor β-induced) collectively known as the epithelial-stromal TGFBI dystrophies. Most cases of epithelial basement membrane dystrophy (EBMD) are thought to result from a degenerative (nongenetic) process; however, a minority of cases are associated with specific TGFBI mutations. We evaluated the spectrum of TGFBI mutations and associated phenotypes in a United Kingdom cohort with typical epithelial-stromal TGFBI dystrophies and an EBMD cohort. Methods: We recruited 68 probands with a clinical diagnosis of epithelial-stromal TGFBI dystrophy and 23 probands with bilateral EBMD. DNA was extracted from peripheral leukocytes, and TGFBI was bi-directly Sanger sequenced. Results: Nine TGFBI mutations were identified. The most common occurred at the mutation hot-spot residues R124 and R555 in 61 probands; these individuals had a genotype-phenotype correlation consistent with prior reports. Four probands with lattice corneal dystrophy carried a mutation in exon 14: p.(A620D), p.(V625D), and p.(H626R). We identified a p.(G623D) mutation in five probands, including two probands from the EBMD cohort. These subjects typically had an onset of severe recurrent corneal epithelial erosion in the fourth decade with mild diffuse or geographic subepithelial corneal opacities and only small anterior stromal lattice structures in older individuals. Symptoms of painful epithelial erosion improved markedly following phototherapeutic keratectomy. Conclusions: There was a strong correlation between genotype and phenotype for the majority of TGFBI mutations. In this cohort, the p.(G623D) mutation caused a greater proportion of TGFBI-associated disease than anticipated, associated with variable phenotypes including individuals diagnosed with EBMD.

Lattice Corneal Dystrophy is associated with painful recurrent corneal erosions and amyloid corneal opacities induced by transforming growth factor β induced protein (TGFBIp) that impairs vision. The exact mechanism of amyloid fibril formation in Corneal Dystrophy is unknown but has been associated with destabilizing mutations in the fourth fasciclin 1 (Fas1-4) domain of TGFBIp. The green tea compound Epigallo-catechin gallate (EGCG) has been found to inhibit fibril formation of various amyloidogenic proteins in vitro. In this study we investigated the effect of EGCG as a potential treatment in Lattice Corneal Dystrophy (LCD) using Fas1-4 with the naturally occurring LCD-inducing A546T mutation. A few molar excess of EGCG were found to inhibit fibril formation in vitro by directing Fas1-4 A546T into stable EGCG-bound protein oligomers. Incubation with two molar equivalent EGCG led to a 4-fold reduction in the aggregates' membrane disruptive potential, potentially indicative of significantly lower cytotoxicity with regards to corneal erosions. EGCG did not induce oligomer formation by wildtype Fas1-4, indicating that treatment with EGCG would not interfere with the native function of the wild-type protein. Addition of EGCG to 10-day old fibrils reduced fibril content in a dose-dependent manner. Proteinase K was found to reduce the light scattering of non-treated fibrils by 31%, but reduced that of fibrils treated with eight molar equivalents of EGCG by 85%. This suggests that EGCG remodeling of fibril structure can facilitate aggregate removal by endogenous proteases and thus alleviate the protein deposits' light scattering symptoms.

Purpose To report results of femtosecond laser-assisted lamellar keratectomy (FLK) for corneal opacities secondary to anterior corneal dystrophies. Methods Patients with a clinical diagnosis of Reis-Bucklers corneal dystrophy, granular corneal dystrophy, lattice corneal dystrophy, and macular corneal dystrophy were treated. FLK was performed to remove a central corneal free cap of 9.5 mm in diameter at a depth of 110 to 140 μm on which histological analysis was undertaken. Preoperative and postoperative refraction, best spectacle-corrected visual acuity, corneal topography results, and color photographs were recorded. Postoperative in vivo confocal microscopy of the cornea was performed. Changes in uncorrected visual acuity and best spectacle-corrected visual acuity, keratometry, refractive error, corneal irregularity, residual or recurrent central corneal opacities, and corneal haze were used to assess the outcome. Results Eight eyes of 6 patients were treated. The clinical diagnosis was confirmed histologically in all cases. Visual acuity improved significantly from 0.49 ± 0.2 logMAR to 0.14 ± 0.13 logMAR after a mean follow-up of 29 ± 14 (range 8-54) months. Residual central stromal opacities were noted in 5 of 8 eyes immediately postoperatively. Clinically significant recurrence of disease was noted in 1 eye. Keratometry and refraction remained stable, and no further surgical intervention was needed. Patients with stromal corneal dystrophies had worse outcome than those with Reis-Bucklers corneal dystrophy. Conclusions In this case series, FLK provided both therapeutic and diagnostic intervention, delaying more invasive surgery. In vivo confocal microscopy showed signs of postoperative corneal stromal neuropathy.

The R124C mutation of the TGFBI gene gives rise to lattice corneal dystrophy type I, which is characterized by irregularity, turbulence, and opacity of the corneal epithelium. We investigated the efficacy of corneal epithelial debridement followed by application of autologous fibronectin eye drops in the treatment of patients with this mutation. Four patients (6 eyes; age range 25–57 years) treated between April 2006 and March 2008 were enrolled in the study. All patients had impaired visual acuity and recurrent corneal erosion. Corneal epithelial debridement was performed with a spatula at the pupillary zone, after which eye drops containing fibronectin purified from autologous serum were administered four times daily for 2 weeks to promote epithelial migration. Topical levofloxacin and betamethasone were also applied four times daily for 1 month. All corneas achieved resurfacing within a few days of debridement. The best corrected visual acuity of all eyes improved from an average logMAR of 0.80 (range 1.40 logMAR–0.52 logMAR) before treatment to a logMAR of 0.10 (range 0.30 logMAR–0.046 logMAR) by 2–4 months after debridement. Despite the limitation of this study setting, corneal epithelial debridement followed by administration of fibronectin eye drops seems to be effective in improving visual acuity in cases of lattice corneal dystrophy type I caused by the R124C mutation of the TGFBI gene. This treatment may be one option for temporarily improving visual acuity in lattice corneal dystrophy type I and thus may delay the requirement for phototherapeutic keratoplasty or keratoplasty.

Purpose An atypical case of late-onset lattice corneal dystrophy is described in a 61-year-old man without a family history of eye disease. Mutational analysis of the TGFBI gene excluded any pathogenic sequence variants. However, 2 years later, renal impairment and nephrotic syndrome were diagnosed, resulting in a diagnosis of systemic heavy-chain amyloidosis. Methods Slit-lamp examination, corneal photography, and in vivo confocal microscopy were performed. General systemic evaluation included blood and urine assessment, bone marrow and renal biopsies, and cardiologic evaluation. A DNA sample underwent initial mutational analysis of TGFBI and, subsequently, gelsolin. The renal biopsy sample was subject to direct protein sequencing by mass spectrometry. Results A bilateral, atypical, fine, midperipheral lattice corneal dystrophy with minor central subepithelial scarring was clinically characterized. Subsequently, abnormal renal functions with proteinuria, IgG lambda paraproteinemia, extensive deposition of amyloid in renal glomeruli, and increased plasma cells in bone marrow were identified. No pathogenic sequence mutations were identified in TGFBI or the gelsolin genes. Direct protein sequencing by mass spectrometry showed amyloid to be heavy-chain deposition rather than the more usual light-chain deposition. Conclusions Atypical midperipheral lattice corneal dystrophy presenting with adult onset and negative family history should arouse suspicion for an association with paraproteinemias or amyloidosis. Exclusion of TGFBI mutations should alert the clinician to the possibility of potentially life-threatening conditions, with referral for careful systemic evaluation.

Background To describe mutations in the transforming growth factor-beta induced ( TGFBI ) gene in Asian patients with Bowman9s membrane as well as stromal corneal dystrophies, and to elucidate their structural implications, using model peptides. Methods Twenty-two unrelated Asian families were examined clinically including visual acuity testing and ocular examination with slit lamp biomicroscopy. Genomic DNA was extracted and the 17 exons of the TGFBI gene were amplified by PCR and sequenced bi-directionally. Biophysical techniques were used to characterise the wild type and mutant model peptides. Results Molecular genetic analysis identified a variety of mutations in our patient series including a novel heterozygous C to A transversion mutation in exon 14 (c.1859C→A), resulting in a substitution of a highly conserved alanine residue by aspartic acid (p.A620D). Clinical presentation in the patient with the p.A620D included subepithelial scarring in addition to the linear branching opacities usually seen with lattice dystrophy. Using model peptides, we showed that A620D mutant peptide alters the secondary structure and conformational stability, and increased amyloid formation. Conclusion A novel mutation (A620D) in transforming growth factor-beta induced protein (TGFβIp) is described, expanding the repertoire of mutations in this protein. Using model peptides, we demonstrated that A→D substitution leads to perturbation of the secondary structure that may be responsible for the amyloid formation in lattice corneal dystrophy.

This research was originally published in the Journal of Biological Chemistry. Daisaku Ozawa, Yuichi Kaji, Hisashi Yagi, Kazumasa Sakurai, Toru Kawakami, Hironobu Naiki, and Yuji Goto. Destruction of Amyloid Fibrils of Keratoepithelin Peptides byLaser Irradiation Coupled with Amyloid-specific Thioflavin T. J. Biol. Chem. 2011; 286, 10856-10863. © the American Society for Biochemistry and Molecular Biology, Mutations in keratoepithelin are associated with blinding ocular diseases, including lattice corneal dystrophy type 1 and granular corneal dystrophy type 2. These diseases are characterized by deposits of amyloid fibrils and/or granular non-amyloid aggregates in the cornea. Removing the deposits in the cornea is important for treatment. Previously, we reported the destruction of amyloid fibrils of β2-microglobulin K3 fragments and amyloid β by laser irradiation coupled with the binding of an amyloid-specific thioflavin T. Here, we studied the effects of this combination on the amyloid fibrils of two 22-residue fragments of keratoepithelin. The direct observation of individual amyloid fibrils was performed in real time using total internal reflection fluorescence microscopy. Both types of amyloid fibrils were broken up by the laser irradiation, dependent on the laser power. The results suggest the laser-induced destruction of amyloid fibrils to be a useful strategy for the treatment of these corneal dystrophies.

PURPOSE The aim of this study was to report the persistent staining of corneal lattice lines resulting from the intraoperative use of trypan blue. METHODS This is a case series. RESULTS Four patients with lattice corneal dystrophy (LCD) who underwent either deep anterior lamellar keratoplasty or cataract extraction with intraoperative trypan blue use demonstrated persistent, postoperative trypan staining of lattice lines on slit-lamp examination out to final follow-up (range, 176 to 541 days postoperatively). CONCLUSIONS This case series demonstrates the previously unreported finding that intraoperative trypan blue stains corneal lattice lines in LCD. Trypan blue staining, localized in previous laboratory studies to amyloid deposits, seems to persist for months or longer and may be permanent in human tissue. Although the staining was not visually significant, animal models suggest a stimulatory effect on progression of amyloidosis. Clinicians should be aware of the potential for permanent corneal staining and possible disease progression with the use of intraoperative trypan blue in patients with LCD.

We report a patient with lattice corneal dystrophy type II, also known as Meretoja syndrome or familial amyloidosis Finnish type, who developed a corneal melt 15 days after uneventful phacoemulsification. Despite conservative treatment, the corneal melt resulted in perforation. Uneventful penetrating keratoplasty was performed, but delayed graft epithelial healing was noticed postoperatively. Corneal button histopathological evaluation confirmed the initial clinical diagnosis. To our knowledge, this is the first reported case of corneal melt and perforation in a patient with lattice corneal dystrophy type II.

Purpose To report the clinical and histopathologic features of accelerated TGFBI protein (TGFBIp) deposition after lamellar keratorefractive surgery in a patient with combined granular-lattice corneal dystrophy (CGLCD) who underwent bilateral corneal transplantation. Design Interventional case report. Methods A 28-year-old woman with a presumed TGFBI corneal dystrophy, but who retained best corrected visual acuity of 20/20 in each eye, underwent myopic laser-assisted in-situ keratomileusis (LASIK) both eyes (OU). For definitive diagnosis of the corneal dystrophy, buccal epithelial cells were collected as a source of genomic DNA and screening of TGFBI exons 4 and 12 was performed. Results Four months after the performance of an uncomplicated LASIK procedure, the patient’s uncorrected visual acuity was 20/15 OU. Over the following two years, the appearance of confluent white stromal deposits at the LASIK flap interface resulted in disabling glare and a reduced best-corrected visual acuity of 20/40 OU. Corneal transplantation was performed in each eye, and histopathologic examination of the excised corneal buttons was performed. Eosinophilic material that stained positively with the Masson trichrome stain was present in the LASIK flap interface, as well as in the stroma of the flap and the anterior portion of the stromal bed. No amyloid deposits were identified with the Congo red stain. Screening of TGFBI exons 4 and 12 revealed the Arg124His mutation associated with CGLCD. Conclusions Accelerated deposition of TGFBIp may occur after lamellar corneal surgery in patients with CGLCD. Therefore, LASIK surgery should be avoided in patients with any of the TGFBI dystrophies, and surgeons should be aware of the potential for rapid interface TGFBIp deposition after lamellar corneal surgery.