Analysis of Corneal Phenotypes in Japanese Patients With Myotonic Dystrophy Type 1.

PURPOSE: To analyze the corneal phenotypes of Japanese patients with myotonic dystrophy type 1 (DM1). METHODS: We included patients with DM1 who were diagnosed with clinical neuromuscular symptoms by neurologists and CTG trinucleotide repeat (TNR) expansion of the (myotonic dystrophy protein kinase) DMPK gene. We analyzed the corneal phenotype using slit-lamp examination, specular microscopy, and anterior segment optical coherence tomography. We evaluated TNR expansion in the TCF4 gene of leukocyte-derived genomic DNA by fragment analysis using polymerase chain reaction and triplet-repeat primed polymerase chain reaction. RESULTS: Nineteen eyes from 10 patients with DM1 (DM1 group) and 72 eyes from 37 healthy participants (control group) were analyzed. The average age was 49.3 ± 11.9 and 51.8 ± 12.9 years in the DM1 and control groups, respectively (P = 0.11). Slit-lamp examination demonstrated that 2 patients with DM1 had bilateral corneal guttae equivalent to modified Krachmer grade 1 of Fuchs endothelial corneal dystrophy. Dark areas on specular microscopy were observed in 4 of 19 eyes (21.1%) and 0 of 72 eyes (0%) in the DM1 and control groups, respectively, with statistically significant differences (P = 0.002). The average endothelial cell density in the DM1 group (3536 ± 722 cells/mm2) was significantly higher than that in the control group (3026 ± 412 cells/mm2) (P = 0.0006). TNR expansion in TCF4 was not detected in eyes with corneal guttae or in the dark areas in the DM1 group. CONCLUSIONS: Japanese patients with DM1 without TNR expansion in TCF4 have a mild phenotype equivalent to Fuchs endothelial corneal dystrophy. Endothelial cell density is higher in DM1 patients than in normal participants.

Comparison of Scheimpflug and Anterior Segment Optical Coherence Tomography Imaging Parameters for Japanese Patients With Fuchs Endothelial Corneal Dystrophy With and Without TCF4 Repeat Expansions.

PURPOSE: The aim of this study was to investigate the association between cytosine-thymine-guanine trinucleotide repeat (TNR) expansion in TCF4 and the clinical phenotypes of corneal densitometry or anterior segment morphology in Fuchs endothelial corneal dystrophy. METHODS: This retrospective cross-sectional study included 150 eyes from 75 Japanese consecutive patients with Fuchs endothelial corneal dystrophy. Cytosine-thymine-guanine repeat expansion of leukocyte-derived genomic DNA was analyzed through fragment analysis using polymerase chain reaction and triplet repeat primed polymerase chain reaction. Scheimpflug-based densitometry and anterior segment optical coherence tomography were applied. Corneal densitometry, and corneal and anterior segment morphology parameters were compared between patients with and without TNR expansion of 50 or more (expansion and nonexpansion groups, respectively) using a mixed model. RESULTS: The average age of the patients was 66.8 ± 13.0 years, and the modified Krachmer grading scale was 1, 2, 3, 4, 5, and 6 for 7, 32, 28, 51, 6, and 18 eyes, respectively. Sixteen patients (21%) exhibited ≥50 TNR expansion. No significant differences in sex, age, history of keratoplasty, modified Krachmer grade, and corneal densitometry in either diameter or depth were observed between the 2 groups. No significant differences in anterior segment morphology, including the anterior chamber depth and anterior chamber angle width parameters, were observed using a univariate mixed model, except for central corneal thickness (P = 0.047). However, according to the multivariate mixed model, repeat expansion was not significantly associated with central corneal thickness (P = 0.27). CONCLUSIONS: No significant differences in clinical phenotypes were found between Japanese patients having Fuchs endothelial corneal dystrophy with and without TNR expansion.

Corneal Opacity Induced by Light in a Mouse Model of Gelatinous Drop-Like Corneal Dystrophy.

Gelatinous drop-like corneal dystrophy (GDLD) is a severe inherited corneal dystrophy characterized by subepithelial corneal amyloid deposition. We had previously succeeded in identifying the responsible gene, TACSTD2, and subsequently found that the epithelial barrier function is significantly decreased. As with GDLD patients, the knockout mice showed severe loss of tight junction, progressive opacity, and neovascularization in the cornea. We devised an easy method to confirm the loss of the corneal barrier function even before corneal opacity is observed. Furthermore, by using knockout mice, we were able to verify clinical findings, such as the wound healing delay and light-induced acceleration of the disease. This mouse model should prove to be a highly useful tool for investigating the pathology of GDLD and for developing new therapies.