Macular corneal dystrophy (MCD; MIM 217800) is an autosomal recessive hereditary disease in which progressive punctate opacities in the cornea result in bilateral loss of vision, eventually necessitating corneal transplantation. MCD is classified into two subtypes, type I and type II, defined by the respective absence and presence of sulphated keratan sulphate in the patient serum, although both types have clinically indistinguishable phenotypes. The gene responsible for MCD type I has been mapped to chromosome 16q22, and that responsible for MCD type II may involve the same locus. Here we identify a new carbohydrate sulphotransferase gene (CHST6), encoding an enzyme designated corneal N-acetylglucosamine-6-sulphotransferase (C-GlcNAc6ST), within the critical region of MCD type I. In MCD type I, we identified several mutations that may lead to inactivation of C-GlcNAc6ST within the coding region of CHST6. In MCD type II, we found large deletions and/or replacements caused by homologous recombination in the upstream region of CHST6. In situ hybridization analysis did not detect CHST6 transcripts in corneal epithelium in an MCD type II patient, suggesting that the mutations found in type II lead to loss of cornea-specific expression of CHST6.

Autologous transplantation of cultivated corneal epithelium is feasible by using acellular amniotic membrane as a carrier.

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Keratin 12 (K12) is an intermediate-filament protein expressed specifically in corneal epithelium. Recently, we isolated K12 cDNA from a human corneal epithelial cDNA library and determined its full sequence. Herein, we present the exon-intron boundary structure and chromosomal localization of human K12. In addition, we report four K12 mutations in Meesmann corneal epithelial dystrophy (MCD), an autosomal dominant disorder characterized by intraepithelial microcysts and corneal epithelial fragility in which mutations in keratin 3 (K3) and K12 have recently been implicated. In the human K12 gene, we identified seven introns, defining eight individual exons that cover the coding sequence. Together the exons and introns span approximately 6 kb of genomic DNA. Using FISH, we found that the K12 gene mapped to 17q12, where a type I keratin cluster exists. In this study, four new K12 mutations (Arg135Gly, Arg135Ile, Tyr429Asp, and Leu140Arg) were identified in three unrelated MCD pedigrees and in one individual with MCD. All mutations were either in the highly conserved alpha-helix-initiation motif of rod domain 1A or in the alpha-helix-termination motif of rod domain 2B. These sites are essential for keratin filament assembly, suggesting that the mutations described above may be causative for MCD. Of particular interest, one of these mutations (Tyr429Asp), detected in both affected individuals in one of our pedigrees, is the first mutation to be identified within the alpha-helix-termination motif in type I keratin.

Aim-To study herpes simplex virus (HSV) DNA in tears from patients with atypical epithelial keratitis of unknown aetiology. Methods-Tear samples were collected from 17 aVected eyes of 17 consecutive patients suVering from epithelial keratitis in whom HSV keratitis was suspected but whose diagnosis was diYcult on the basis of clinical manifestations alone. Using reduced sensitivity polymerase chain reaction (PCR), tear samples were tested for HSV DNA. Tears from the unaVected eyes of the 17 patients were also examined, along with 38 tear samples from 19 normal volunteers. Southern blot analysis was performed to confirm that amplified DNA bands were specific for HSV. Clinical correlation with photographs of corneal lesions was also investigated. Results-HSV DNA was detected in tears from the aVected eyes of eight of the 17 patients with suspected HSV keratitis. Tears from the aVected eyes of the other patients were PCR negative, as were tears from the unaVected eyes of all 17 patients, and from the 38 normal eyes. There was no correlation between PCR results and clinical manifestation of keratitis. Conclusions-Based on the sensitivity of the PCR system, eight of 17 suspected HSV keratitis patients were confirmed as suVering from HSV keratitis. HSV keratitis should therefore be considered as a possible diagnosis in atypical epithelial keratitis. (Br J Ophthalmol 1999;83:957-960) Herpes simplex virus (HSV) epithelial keratitis, a leading cause of corneal blindness, is typified by dendritic or geographical corneal ulcers, which usually have dendritic edges with terminal bulbs and epithelial infiltration. This enables them to be diVerentiated from corneal ulcers due to other causes, and their clinical diagnosis as herpetic keratitis. Sometimes, however, such factors as duration since onset, previous medication, systemic diseases (atopic dermatitis, 1 for example), or history of corneal transplantation 2 can make the epithelial lesions appear diVerent from classic HSV lesions. The initial diagnosis is very important, since it decides the use of antiviral drugs, such as aciclovir. In atypical cases, however, it is often diYcult to make a correct diagnosis based solely on the clinical presentation.Since Saiki et al's 1985 report on the usefulness of the polymerase chain reaction (PCR) for diagnostic purposes, 3 it has often been used for diagnosing viral diseases of the eye. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Previously, we established a reduced sensitivity PCR for diagnosing HSV epithelial keratitis, [4][5][6][7] corneal endothelitis, 8 and HSV related uveitis.9 10 Using this PCR system, we are able to detect HSV DNA in tears from patients with clinically diagnosed HSV epithelial keratitis. The sensitivity of this system is higher than that of viral culture, while being low enough not to give a positive PCR result in normal tears. 4 5 In the present study, we used the reduced sensitivity PCR system to investigate HSV DNA in tears from suspected epithelial keratitis patie...

The high epithelial permeability observed in GDLD corneas was directly correlated with abnormalities in epithelial structure, including irregular cell junctions. This suggests that the abnormal M1S1 gene product may affect epithelial cell junctions resulting in increased cell permeability in GDLD corneas.

In Stevens-Johnson syndrome, pathological keratinization of the ordinarily nonkeratinized corneal and conjunctival mucosal epithelia results in severe visual loss. We examined conjunctiva covering cornea in five eyes in the chronic cicatricial phase of Stevens-Johnson syndrome. Normal conjunctiva from five age-matched individuals was studied also. The number of epithelial cells in Stevens-Johnson syndrome conjunctiva that were immunoreactive with a monoclonal antibody, Ki-67, to a nuclear antigen found only in proliferating cells was greater than normal (93.8+/-19.8 cells above 100 basal cells versus 12.8+/-0.5 cells above 100 basal cells; P = 0.009). In addition, although clinical inflammation was mild, massive lymphocytic infiltration was seen in the substantia propria of conjunctiva covering cornea. In situ hybridization documented transglutaminase 1 (keratinocyte transglutaminase) mRNA in suprabasal cells of the abnormally thickened conjunctival epithelium in all Stevens-Johnson syndrome patients. In contrast, no message was detected in normal conjunctival or corneal epithelia. Transglutaminase 1 is expressed during the terminal differentiation of keratinocytes where it helps synthesize cornified cell envelopes. We speculate that in Stevens-Johnson syndrome, epithelial hyperproliferation, and transglutaminase 1 gene expression lead to the pathological keratinization of ocular surface mucosal epithelia.