Primary familial amyloidosis of the cornea

Sutureless Customized Lamellar Corneal Transplant in a Patient with Gelatinous Drop-Like Corneal Dystrophy

Patients with gelatinous drop-like corneal dystrophy need to be effectively managed as the disease is severely debilitating in view of associated pho-tophobia and glare. Here, we report a rare case of gelatinous drop-like corneal dystrophy effectively managed by intraoperative anterior segment optical coherence tomography-guided manual deep anterior lamellar keratoplasty in 1 eye and sutureless fibrin glue-aided, microkeratome-assisted automated lamellar therapeutic keratoplasty in the other eye. The patient, a 22-year old man, presented with gradual diminution of vision associated with foreign body sensation, glare, photophobia, and watering due to corneal lesions, which were consistent with a diagnosis of gelatinous drop-like corneal dystrophy. Visual acuity at pre-sentation was 4/60 and 3/60 in the right and left eye, respectively. The patient received customized component lamellar keratoplasty in both eyes, and host tissue was sent for histopathologic examination. Treatment resulted in a best-corrected distance visual acuity of 6/9 and 6/12 in the right and left eye, respectively. The graft was clear and well apposed, with minimal interface haze bilaterally. The histopathologic report suggested intralamellar amyloid deposition in the form of homogenous, acellular eosinophilic deposits in the epithelium and anterior corneal stroma. This is a first report of the exclusive use of a fibrin-aprotinin tissue adhesive to stabilize a donor corneal lamellar graft as a treatment modality for a patient with gelatinous drop-like corneal dystrophy, suggesting that this treatment could supplant the need for sutures.

Gelatinous drop-like corneal dystrophy: a review

Gelatinous drop-like corneal dystrophy (GDLD) is a rare autosomal recessive form of corneal dystrophy characterised by subepithelial and stromal amyloid deposits. It is relatively common in Japan. It usually presents in the first two decades of life with subepithelial nodular lesions that later coalesce to form mulberry-like opacities. Although various surgical modalities have been attempted, recurrence remains a major challenge.

Spectrum of Clinical Signs and Genetic Characterization of Gelatinous Drop-Like Corneal Dystrophy in a Colombian Family

PURPOSE

To describe the clinical signs of gelatinous drop-like corneal dystrophy (GDLD) in a consanguineous Colombian family and determine the underlying genetic cause.

METHODS

We performed ocular examination of available family members and bidirectionally Sanger sequenced the GDLD-associated gene, TACSTD2. In one individual, the presence of subepithelial amyloid was confirmed with biopsy.

RESULTS

The parents were consanguineous and 5 of their 10 children had GDLD. Typical mulberry subepithelial deposits with subepithelial vascularization were present in 3 individuals; 2 individuals only had mild polymorphic anterior stromal opacity. We identified a homozygous TACSTD2 missense mutation, c.551A>G, p.(Tyr184Cys), in the affected family members. Both parents were heterozygous for the mutation, and unaffected siblings were either heterozygous or homozygous wild-type for this allele. In the Colombian population, this mutation has a minor allele frequency of 0.53%.

CONCLUSION

The clinical presentation of GDLD in this family was variable and does not solely support an age-dependent progression of the phenotype, suggesting that environmental or other genetic factors can modify phenotypic expression. The relatively high prevalence of this mutation in the Colombian population suggests that other individuals may have undiagnosed subclinical disease.

Familial Gelatinous Drop-Like Corneal Dystrophy Caused by a Novel Nonsense TACSTD2 Mutation

PURPOSE

To describe the clinical findings and results of molecular analysis in a Mexican family diagnosed with gelatinous drop-like corneal dystrophy (GDLD).

METHODS

Ophthalmological examination was performed in 1 unaffected and 4 affected relatives. Molecular analysis included polymerase chain reaction amplification and direct nucleotide sequencing of the entire TACSTD2 gene-coding region in genomic DNA.

RESULTS

The corneal phenotype in adult patients was characterized by white-yellow nodular lesions on the corneal surface and stromal neovascularization. Lesions were incipient in an affected relative aged 14 years. Nucleotide sequencing of the TACSTD2 gene demonstrated a homozygous c.331G>T transversion, which predicts a novel p.(E111*) nonsense mutation, in DNA of all 4 GDLD relatives.

CONCLUSIONS

Our results expand the mutational spectrum of TACSTD2 in patients with GDLD. To the best of our knowledge, this is the first clinical and molecular description of patients with GDLD from Latin America.

Tumor-associated calcium signal transducer 2 is required for the proper subcellular localization of claudin 1 and 7: implications in the pathogenesis of gelatinous drop-like corneal dystrophy

Gelatinous drop-like dystrophy (GDLD) is a rare autosomal recessive form of corneal dystrophy characterized by subepithelial amyloid depositions on the cornea. Previous clinical and laboratory observations have strongly suggested that epithelial barrier function is significantly decreased in GDLD. Despite the decade-old identification of the tumor-associated calcium signal transducer 2 (TACSTD2) gene as a causative gene for GDLD, the mechanism by which the loss of function of this causative gene leads to the pathological consequence of this disease remains unknown. In this study, we investigated the functional relationship between the TACSTD2 gene and epithelial barrier function. Through the use of immunoprecipitation and a proximity ligation assay, we obtained evidence that the TACSTD2 protein directly binds to claudin 1 and 7 proteins. In addition, the loss of function of the TACSTD2 gene leads to decreased expression and change in the subcellular localization of tight junction-related proteins, including claudin 1, 4, 7, and ZO1 and occludin, both in diseased cornea and cultured corneal epithelial cells. These results indicate that loss of function of the TACSTD2 gene impairs epithelial barrier function through decreased expression and altered subcellular localization of tight junction-related proteins in GDLD corneas.

A missense mutation in the M1S1 gene found in a turkish patient with gelatinous droplike corneal dystrophy

PURPOSE

To report a missense mutation in the M1S1 gene found in a Turkish patient with gelatinous droplike corneal dystrophy (GDLD).

METHODS

A Turkish patient with GDLD was examined. Keratoplasty was performed and a diagnosis of GDLD was made by histopathologic and electron microscopic studies. Genomic DNA was extracted from peripheral blood and the paraffin-embedded tissue of the corneal button. A 248-bp DNA fragment of the M1S1 gene was amplified, and sequencing reactions were analyzed. The results were compared with those of 30 healthy, nonrelated individuals.

RESULTS

On light microscopic examination, sheets of amorphous amyloid deposits were observed in subepithelial regions and in the anterior and midcorneal stroma. Electron microscopy revealed dense collagen fibrils and entrapped filamentous amyloid fibrils in the corneal stroma. A substitution of T-->C at nucleotide 557 was found in the peripheral blood DNA sequence analysis, which resulted in an amino acid substitution of L-->P (L186P). Results were confirmed by direct DNA sequencing analysis of the paraffin-embedded corneal button. The patient with GDLD was homozygous for the mutation, resulting in amino acid substitution L186P.

CONCLUSIONS

This is the first report, to our knowledge, of a homozygous mutation (L186P) in the M1S1 gene found in a Turkish patient. The clinical examination may be insufficient in sporadic cases, and histopathologic examination and molecular genetic analysis can accelerate and improve the accuracy of diagnosis in patients with GDLD.

A spectrum of clinical manifestations of gelatinous drop-like corneal dystrophy in japan

PURPOSE

Typical manifestations of gelatinous drop-like corneal dystrophy (GDLD) have been documented in past studies. In practice, however, we see few typical cases and encounter many with atypical clinical manifestations. Moreover, there have been no detailed reports about the various clinical presentations. The purpose of this study is to describe a clinical subclassification for GDLD.

DESIGN

Observational case series.

METHODS

A retrospective, observational case series study was conducted at a single institution, Osaka University Hospital. Examined were 18 eyes of ten patients with GDLD with no prior surgery. All were found to have M1S1 mutations. Using slit-lamp examinations we performed a phenotypic classification.

RESULTS

We classified GDLD patients into four groups. They included band keratopathy type (seven eyes of four patients), stromal opacity type (five eyes of three patients), kumquat-like type (four eyes of two patients), and typical mulberry type (two eyes of two patients).

CONCLUSIONS

Gelatinous drop-like corneal dystrophy is thought to be the result of mutations in M1S1; however, it has various clinical manifestations. To our knowledge, this study is the first to report the range of clinical phenotypes of GDLD in a Japanese population. As most clinicians have no criteria for diagnosing GDLD, many cases are likely to be overlooked or be mistaken for other conditions. We believe that our present classification will be useful for the diagnosis of GDLD.

Subepithelial amyloid deposits in congenital hereditary endothelial dystrophy: a histopathologic study of five cases

PURPOSE

To report the clinical, histologic, ultrastructural, and immunohistochemical features of congenital hereditary endothelial dystrophy (CHED) associated with subepithelial amyloid deposits.

METHODS

The clinical features of seven patients and histologic characteristics of eight corneal buttons were evaluated. The corneal specimens included five cases with histologic features of CHED associated with subepithelial amyloid. The remaining three corneal buttons of CHED without amyloid were obtained from the fellow eye of an affected patient and from siblings of two affected patients. Light microscopic studies were performed on sections stained with hematoxylin and eosin, periodic acid Schiff stain, and Congo red stain with and without permanganate bleach. Immunohistochemistry with an antibody to the amyloid AA protein and lambda and kappa light chains was done on all specimens. Electron microscopy was performed on three corneal specimens. The cases were followed for 1-9 years.

RESULTS

The notable clinical findings included decreased vision, history of parental consanguinity (4/7 cases), and affected siblings (5/7 cases). Examination revealed nystagmus (5/7 cases) and bilateral ground-glass corneas in all patients. In addition, central subepithelial whitish opacities were noted in patients with CHED and amyloid. Three patients had associated congenital glaucoma. The patients underwent penetrating keratoplasty at a mean age of 10 years. Histologically, five corneal buttons of CHED revealed varying degrees of subepithelial amyloid deposits associated with a subepithelial fibrous pannus. Immunohistochemically, the deposits were nonreactive to anti-amyloid A antibody but were immunoreactive with an antibody to lambda light chains in two cases. Electron microscopy confirmed the presence of subepithelial amyloid. Thickening of Descemet's membrane and attenuation of corneal endothelial cells, noted in all cases, was consistent with features of CHED. The corneal buttons from the fellow eye and the siblings showed histologic features of CHED, with a subepithelial fibrous pannus without amyloid deposits. Spheroidal degeneration was noted in two corneal specimens. To date, no recurrence of the amyloid deposits has been seen in the grafts.

CONCLUSIONS

This study demonstrates that subepithelial amyloidosis may be rarely associated with a recessive form of congenital hereditary endothelial dystrophy. The clinical, histologic, and immunohistochemical features suggest a secondary form of amyloidosis.

Identification of the gene responsible for gelatinous drop-like corneal dystrophy

Gelatinous drop-like corneal dystrophy (GDLD; OMIM 204870) is an autosomal recessive disorder characterized by severe corneal amyloidosis leading to blindness, with an incidence of 1 in 300,000 in Japan. Our previous genetic linkage study localized the gene responsible to a 2.6-cM interval on chromosome 1p. Clinical manifestations, which appear in the first decade of life, include blurred vision, photophobia and foreign-body sensation. By the third decade, raised, yellowish-grey, gelatinous masses severely impair visual acuity, and lamellar keratoplasty is required for most patients. Here we report DNA sequencing, cDNA cloning and mutational analyses of four deleterious mutations (Q118X, 632delA, Q207X and S170X) in M1S1 (formerly TROP2 and GA733-1), encoding a gastrointestinal tumour-associated antigen. The Q118X mutation was the most common alteration in the GDLD patients examined, accounting for 33 of 40 (82.5%) disease alleles in our panel of families. Protein expression analysis revealed aggregation of the mutated, truncated protein in the perinuclear region, whereas the normal protein was distributed diffusely in the cytoplasm with a homogenous or fine granular pattern. Our successful identification of the gene that is defective in GDLD should facilitate genetic diagnosis and potentially treatment of the disease, and enhance general understanding of the mechanisms of amyloidosis.

Homozygosity mapping of a gene responsible for gelatinous drop-like corneal dystrophy to chromosome 1p

Gelatinous drop-like corneal dystrophy (GDLD) is a rare autosomal recessive disorder characterized clinically by grayish corneal deposits of amyloid and by severely impaired visual acuity. Most patients require corneal transplantation. To localize a gene responsible for GDLD, we performed linkage analysis of 10 consanguineous Japanese families with a total of 13 affected members. Homozygosity mapping provided a maximum LOD score of 9.80 at the D1S2741 marker locus on the short arm of chromosome 1. Haplotype analysis further defined the disease locus within a region of approximately 2.6 cM between D1S2890 and D1S2801.

Ocular amyloidosis, with special reference to the hereditary forms with vitreous involvement

The complex of diseases referred to as amyloidosis is characterized by the deposition of amyloid substance in various tissues. The amyloid protein differs in the various forms of amyloidosis. This variation is the basis of the differences in affected tissues and subsequent clinical dissimilarities. Vitreous involvement in amyloidosis seems to be especially linked to some of the hereditary neuropathies associated with the amyloid protein transthyretin. Characterization of the amyloid proteins during recent decades has allowed a chemical and immunologic classification of amyloid fibrils. This paper presents the basis for classification of amyloidosis, reviews the literature on ocular amyloidosis, with special reference to vitreous involvement, and summarizes clinical findings and frequency of vitreous amyloid involvement in Swedish patients with familial amyloidotic polyneuropathy.

Spheroidal keratopathy associated with subepithelial corneal amyloidosis. A clinicopathologic case report and a proposed new classification for spheroidal keratopathy

PURPOSE

An unusual case of primary spheroidal degeneration associated with subepithelial corneal amyloidosis is described clinically and histopathologically, and a new classification for spheroidal keratopathy is proposed.

METHODS

The corneal button obtained by lamellar keratoplasty was examined by light and transmission electron microscopy. Amyloid deposits were evaluated further by means of the thioflavin T fluorescence technique, the potassium permanganate reaction, and immunohistochemical studies using antibodies against immunoglobulin light chains and proteins AA and AP.

RESULTS

Spheroidal droplets were observed in basement membrane, Bowman's layer, and anterior stroma, and exhibited characteristic staining with Verhoeff's iron hematoxylin. Amyloid deposits were found beneath the epithelium, almost exclusively in the central area of the corneal button. The deposits showed no immunohistochemical staining with antibodies to amyloid proteins AA and AP or kappa and lambda light chains.

CONCLUSIONS

The histochemical properties of the spheroidal droplets in this case were similar to those observed by other authors and suggested a sulfur-rich protein other than keratin. The combination of clinical and pathologic findings permitted the differential diagnosis of subepithelial amyloidosis and distinguished this condition from that of gelatinous drop-like dystrophy. To the authors' knowledge, this is the first description of primary spheroidal keratopathy associated with secondary subepithelial corneal amyloidosis in an eye that had not undergone previous keratoplasty.

Primary localized amyloidosis of the lacrimal glands

Primary localized amyloidosis causing bilateral lacrimal enlargement is rare. The pathogenesis of amyloid deposition within the orbit and other body tissues has not been fully elucidated. The authors report the case of a 72-year-old woman who presented with bilateral lacrimal gland enlargement secondary to amyloid infiltration. The chemical nature of the deposit was characterized using light microscopy, immunohistochemistry, and immunoelectron microscopy. The primary (immunocytic) nature of the amyloid was confirmed by immunohistochemistry demonstrating the presence of monoclonal lambda light chains in the amyloid deposits and in the plasma cells. Using immunoelectron microscopy, amyloid deposits were seen containing lambda light chains in macrophages. It has been postulated that the macrophage has a role in amyloid deposition. The authors believe this to be the first published report of immunoelectron microscopy use in orbital amyloidosis, and that this technique has helped further their understanding of the nature and pathogenesis of this condition.

Clinical and histopathologic studies of two families with lattice corneal dystrophy and familial systemic amyloidosis (Meretoja syndrome)

Lattice corneal dystrophy associated with familial systemic amyloidosis (Meretoja syndrome) has rarely been described other than in patients of Finnish origin. The authors report two North American patients with this disease who manifest blepharochalasis, lattice corneal dystrophy, open-angle glaucoma, and cranial neuropathy. In one patient, a corneal intraepithelial and subepithelial pseudodendrite was managed by superficial keratectomy, and this same patient benefited from surgical brow suspension for facial muscular weakness. In the second patient, penetrating keratoplasty was complicated by a neurotrophic persistent epithelial defect. Corneal tissue from both superficial keratectomy and penetrating keratoplasty exhibited ultrastructurally characteristic amyloid filaments and associated elastoid material. Transmission electron microscopy of conjunctiva and skin biopsies similarly revealed amyloid deposits associated with most basement membranes, the perineurium and endoneurium of most peripheral nerves, and the intima and media of arteries. By immunoperoxidase staining, the corneal amyloid deposits were positive for the amyloid P-component protein but negative for the nonimmunoglobulin amyloid A protein and prealbumin. Serum prealbumin and amyloid A related protein were normal.

Scleromyxedema with corneal deposits

Scleromyxedema (Arndt-Gottron syndrome) is a rare cutaneous disease in which hyaluronic acid is deposited in the dermis. The authors describe a patient with scleromyxedema and corneal deposits. A corneal biopsy demonstrated hyaluronic acid deposition in the corneal stroma and amyloid P component in Bowman's membrane. This is the first report of scleromyxedema involving the cornea. It is also the first report of amyloid P component deposition in the cornea occurring independent of corneal amyloid deposits.

Immunoglobulin deposition in localized conjunctival amyloidosis

Immunofluorescent studies were performed on tarsus and tarsal conjunctiva from a 30-year-old woman with blepharoptosis secondary to localized nonfamilial amyloidosis. Both kappa and lambda light chains were identified in abundance in the resected tissue. There was no evidence of any systemic disease or of amyloid deposition elsewhere. Six months after the patient underwent surgery, there was no sign of recurrence. The antigenic determinants of the amyloid suggested that the pathogenesis of localized nonfamilial ocular amyloidosis involves the accumulation of proteins similar to immunoglobulin.

Lack of evidence for protein AA reactivity in amyloid deposits of lattice corneal dystrophy and amyloid corneal degeneration

Amyloid fibrils occurring in primary and myeloma-associated (AL), secondary (AA), and certain neuropathic hereditary forms of systemic amyloidosis can be distinguished biochemically or immunohistologically as being composed of immunoglobulin light chain, protein AA, or prealbumin respectively. All types of systemic and several localized forms of amyloidosis contain amyloid P component (protein AP). We studied formalin-fixed tissue from eight cases of lattice corneal dystrophy by the immunoperoxidase method using antisera to proteins AA and AP, to normal serum prealbumin and prealbumin isolated from a case of hereditary amyloidosis, and to light-chain determinants; additional cases were examined by indirect immunofluorescence of fresh-frozen material. We found weak (1:10 dilution) staining with anti-AP, but no reactivity with other antisera. Congo red staining was resistant to pretreatment of sections with potassium permanganate, a characteristic of non-AA amyloid. Two-dimensional gels of solubilized proteins from frozen tissue from two cases of lattice corneal dystrophy resembled those obtained from normal human cornea. Western blots of two cases of polymorphous amyloid degeneration and solubilized protein from normal cornea did not react with radioactive iodine-labeled anti-AA or anti-AP with purified protein AP and unfixed protein AA amyloid tissue as controls. We were unable to corroborate the presence of protein AA in the amyloid deposits of lattice corneal dystrophy. Although staining with antiserum to protein AP was demonstrable, the molecular configuration of this protein in stromal deposits remains to be defined.

Lattice corneal dystrophy associated with familial systemic amyloidosis (Meretoja's syndrome)

A 79-year-old white man of Irish descent presented with lattice corneal dystrophy, blepharochalasis, and peripheral seventh cranial nerve palsies. Family studies revealed that his 23-year-old daughter had early lattice cornea dystrophy. The corneal button removed by penetrating keratoplasty exhibited characteristic amyloid accumulation by light and electron microscopy. Biopsy of the patient's normal appearing conjunctiva and skin of the lower lid revealed amyloid. Biopsy of the daughter's conjunctiva was negative for amyloid, but her lid skin had characteristic amyloid deposits by light and electron microscopy. Immunoperoxidase strains were negative for AA and AP and serum prealbumin and SAA proteins were normal. Meretoja's syndrome has rarely been described outside a small geographic region in Finland. The clinical and histopathologic findings of this entity are discussed and contrasted to isolated "lattice corneal dystrophy."