The origin of amyloid in gelatinous drop-like corneal dystrophy

Clinical and Ultrastructural Studies of Gelatinous Drop-Like Corneal Dystrophy (GDLD) of a Patient with TACSTD2 Gene Mutation

Purpose

To describe clinical, molecular genetics, histopathologic and ultrastructural findings of gelatinous drop-like corneal dystrophy (GDLD) (OMIM #204870) in a Sudanese patient.

Method

An ocular examination revealed the onset of GDLD in a Sudanese patient (50 years old) at King Khalid Specialist Hospital, Riyadh. The 333 sequence variants in 13 GDLD genes of a DNA sample were screened by Asper Ophthalmics Ltd. It was further confirmed by sequencing. The patient had undergone a penetrating keratoplasty in the right eye. The corneal tissue was processed for histopathology and ultrastructural studies.

Results

Slit-lamp observation showed grayish-white multiple superficial corneal nodules of various sizes in the left and right eye. Both corneas became clear after the surgery. The GDLD deposits in the subepithelial region and in the anterior stroma were confirmed by PAS staining and their apple-green birefringence under polarized light. Ultrastructurally, the amyloid fibrils were very thin and grouped in whorl-like structures, which caused splits between and within the stromal lamellae. Collagen fibrils (CFs) and keratocytes had degenerated. A homozygous c.355T > A mutation in exon 1 of the TACSTD2 (M1S1) gene was detected, and alteration of the amino acid (p.Cysl19Ser in NCBI entry NP_002344.2) was observed.

Conclusion

In our patient with GDLD, a "c.355T > A" mutation in exon 1 of TACSTD2 was detected and believed to be responsible for the alteration of the amino acid leading to the formation of the amyloid deposits. The deposits caused the ultrastructural degeneration of epithelium, Bowman's layer, stroma, and keratocytes of the GDLD cornea.

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.

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.

Limbal stem cell transplantation for the treatment of subepithelial amyloidosis of the cornea (gelatinous drop-like dystrophy)

PURPOSE

Subepithelial amyloidosis of the cornea, or gelatinous drop-like corneal dystrophy (GDD), is a severe form of corneal stromal amyloidosis predominantly found in the Japanese population. GDD causes severe visual disturbances with irritating symptoms, and keratoplasty is inevitably complicated by early recurrence. This study was conducted to evaluate the efficacy of limbal stem cell transplantation (LSCT) for the treatment of GDD.

METHODS

Nine consecutive eyes of seven patients with GDD were treated with LSCT. Limbal grafts were obtained from cadaver eyes. All eyes underwent lamellar or penetrating keratoplasty simultaneously with LSCT. Intensive epithelial management and immunosuppression therapy was performed.

RESULTS

With a mean observation period of 4 years, eight (88.9%) of nine eyes did not show any signs of recurrence. Five grafts remained clear, and seven eyes had an improvement in vision. Glaucoma and rejection were observed in five and three eyes, respectively, and two eyes with glaucoma required surgical intervention.

CONCLUSIONS

Limbal stem cell transplantation is effective for the prevention of recurrence in GDD. Control of intraocular pressure and rejection are the keys to long-term maintenance of clear grafts.

Vitreous amyloidosis in familial amyloidotic polyneuropathy. Report of a case with the Val30Met transthyretin mutation

We present a clinical pathological review of vitreous amyloidosis in a case of familial amyloidotic polyneuropathy, type I. Vitreous opacification was the first manifestation of disease in the proband, who was successfully treated with vitrectomy. The eyes were obtained at autopsy after the patient died from an unrelated cause, and the histopathology is presented here. Analysis of DNA from the pathology specimen revealed the most commonly reported transthyretin mutation, Val30Met. The classification of systemic and ocular amyloidosis as well as the genetics of familial amyloidotic polyneuropathy are briefly reviewed.

Long-term follow-up of patients with familial subepithelial amyloidosis of the cornea

PURPOSE

To investigate the clinical course of patients with familial subepithelial amyloidosis of the cornea (FSA).

METHODS

The authors retrospectively investigated the clinical course of seven Japanese patients with FSA. Corneal specimens obtained at the time of keratoplasty were examined histopathologically.

RESULTS

The mean follow-up period was 20.6 years, including four patients followed for more than 25 years. In all patients, the initial symptoms of photophobia and epiphora started in the first decade of life. All except one patient had their first keratoplasty before 30 years of age. The seven Japanese patients with FSA had a total of 35 keratoplasties, each of which was followed by a severe recurrence of disease. In each patient, subepithelial haziness developed in the graft within 1 year of keratoplasty (mean, 7.9 months). Amyloid deposition typically recurred within a few years (mean, 26.6 months) followed by a deterioration of vision. There was a high incidence of postkeratoplasty complications such as wound dehiscence, glaucoma, and cataract. Histopathologic findings demonstrated that, in the early phase of recurrence, amyloid was deposited between the basal cell of the epithelium and Bowman's layer.

CONCLUSION

Patients with FSA have ocular symptoms with a deterioration in vision from an early decade of life. Conventional surgical approaches were complicated by subepithelial haziness in the first postoperative year, which was followed by a severe recurrence in each patient. New surgical approaches may be indicated in FSA.

Clinical features of a newly recognized type of lattice corneal dystrophy

We examined five patients with an undescribed type of lattice corneal dystrophy. All patients were in the seventh to ninth decades of life and had developed decreasing vision late in life. None of the patients had suffered from recurrent epithelial erosions, there was no overt evidence of systemic amyloidosis, and the lattice lines were much thicker than those usually observed in lattice corneal dystrophy types I and II. Available pedigree data from two families of three patients indicated that the corneal disorder affected several siblings but not the parents or offspring. Two patients had no affected family members. There was no known consanguinity in any of the four families.

Unusual inclusions in stromal macrophages in a case of gelatinous drop-like corneal dystrophy

A 35-year-old man developed gelatinous drop-like corneal dystrophy at age 20. Amyloid deposits were located mainly in the anterior two thirds of the cornea. Ultrastructurally, amyloid fibrils were demonstrated beneath the corneal epithelium and in the cytoplasmic inclusions of the stromal macrophages.