Disease Expression and Familial Transmission of Fuchs Endothelial Corneal Dystrophy With and Without CTG18.1 Expansion

Nanopore sequencing method for CTG18.1 expansion in TCF4 in late-onset Fuchs endothelial corneal dystrophy and a comparison of the structural features of cornea with first-degree relatives

BACKGROUND

To evaluate the relationship between the number of trinucleotide repeats (TNR) in late-onset Fuchs corneal endothelial dystrophy (FCED) and to compare the endothelial properties of FCED, first-degree relatives, and controls.

METHODS

Blood samples were collected from FCEDs to determine TNR number. The FCED patients, first-degree relatives, and controls were examined with specular microscopy for central corneal thickness (CCT), endothelial cell density (ECD), pleomorphism and polymegatism, and with corneal topography for specific indicators such as (i) displacement of thinnest point of cornea, (ii) loss of isopachs, (iii) focal posterior surface depression towards anterior chamber.

RESULTS

This study included 92 patients with FCED, 92 first-degree relatives, and 96 controls. CCT was thickest in FCEDs (558.0 μm) (p < 0.05) while there was no difference between relatives (533.0 μm) and controls (530.4 μm) (p = 0.845). ECD was decreased in both FCED (2069.2 mm2) and relatives (2171.4 mm2) than controls (2822.9 mm2) (p < 0.05 in both). The presence of pleomorphism and polymegatism was significant in patients with FCED (93.4% and 93.4%, respectively), relatives (86.9% and 86.04%, respectively), and controls (8.33% and 1.04%, respectively) (p < 0.05). Specific topographic indicators differed among the groups (p < 0.05). The mean repeat number of the FCED patients was 17.48 ± 4.54 (12-25) times. The TNR number of FCED cases correlated with the relative CCT (p < 0.05, R = 0.615) and cell density (p = 0.009, R = -0.499).

CONCLUSIONS

A strong association between the corneal endothelium in relatives and TNR number of FCEDs was defined. Relatives tended to have fewer corneal endothelial cells, even though they did not have clinical findings.

Systematic review of SLC4A11, ZEB1, LOXHD1, and AGBL1 variants in the development of Fuchs' endothelial corneal dystrophy

Introduction

The pathogenic role of variants in TCF4 and COL8A2 in causing Fuchs' endothelial corneal dystrophy (FECD) is not controversial and has been confirmed by numerous studies. The causal role of other genes, SLC4A11, ZEB1, LOXHD1, and AGBL1, which have been reported to be associated with FECD, is more complicated and less obvious. We performed a systematic review of the variants in the above-mentioned genes in FECD cases, taking into account the currently available population frequency information, transcriptomic data, and the results of functional studies to assess their pathogenicity.

Methods

Search for articles published in 2005-2022 was performed manually between July 2022 and February 2023. We searched for original research articles in peer-reviewed journals, written in English. Variants in the genes of interest identified in patients with FECD were extracted for the analysis. We classified each presented variant by pathogenicity status according to the ACMG criteria implemented in the Varsome tool. Diagnosis, segregation data, presence of affected relatives, functional analysis results, and gene expression in the corneal endothelium were taken into account. Data on the expression of genes of interest in the corneal endothelium were extracted from articles in which transcriptome analysis was performed. The identification of at least one variant in a gene classified as pathogenic or significantly associated with FECD was required to confirm the causal role of the gene in FECD.

Results

The analysis included 34 articles with 102 unique ZEB1 variants, 20 articles with 64 SLC4A11 variants, six articles with 26 LOXHD1 variants, and five articles with four AGBL1 variants. Pathogenic status was confirmed for seven SLC4A11 variants found in FECD. No variants in ZEB1, LOXHD1, and AGBL1 genes were classified as pathogenic for FECD. According to the transcriptome data, AGBL1 and LOXHD1 were not expressed in the corneal endothelium. Functional evidence for the association of LOXHD1, and AGBL1 with FECD was conflicting.

Conclusion

Our analysis confirmed the causal role of SLC4A11 variants in the development of FECD. The causal role of ZEB1, LOXHD1, and AGBL1 variants in FECD has not been confirmed. Further evidence from familial cases and functional analysis is needed to confirm their causal roles in FECD.

Predictors of Receiving Keratoplasty for Fuchs' Endothelial Corneal Dystrophy among Medicare Beneficiaries

PURPOSE

To identify factors associated with receipt of endothelial keratoplasty (EK) and penetrating keratoplasty (PK) in patients with Fuchs' endothelial corneal dystrophy (FECD).

DESIGN

Retrospective cohort study.

PARTICIPANTS

Medicare beneficiaries 65 years of age or older with a FECD diagnosis between 2011 and 2019.

METHODS

The 100% Medicare fee-for-service administrative claims database was queried for treatment-naïve FECD patients. A multivariate logistic regression model including age, race and ethnicity, sex, geography, ocular comorbidities and surgeries, Charlson comorbidity index (CCI), and socioeconomic status was used to identify factors associated with receipt of EK and PK. Kaplan-Meier survival analyses were used to determine the rate of EK after cataract or complex or other anterior segment surgery.

MAIN OUTCOME MEASURES

Factors associated with receipt of an EK or PK, plus rate of EK after cataract or complex or other anterior segment surgery.

RESULTS

Of 719 066 beneficiaries identified, 31 372 (4.4%) received an EK and 2426 (0.3%) received a PK. In a multivariate analysis, female sex decreased likelihood of both EK and PK (adjusted odds ratio 0.83 [95% confidence interval 0.81-0.85] and 0.84 [0.78-0.92], respectively), while Western residence (1.33 [1.29-1.38]; 1.25 [1.11-1.42]) compared to Southern and history of complex or other anterior segment surgery (1.62 [1.54-1.70]; 5.52 [4.97-6.12]) increased the likelihood of both. Compared to Whites, the likelihood of EK was decreased for Black (0.76 [0.72-0.80]), Asian or Pacific Islander (0.54 [0.48-0.61]), and Hispanic or Latino (0.62 [0.55-0.70]) race and ethnicity, while for the same groups likelihood of PK was increased (for Black 1.32 [1.14-1.53]; Asian/Pacific Islander 1.46 [1.13-1.89]; and Hispanic/Latino 1.62 [1.25-2.11]). Following cataract or complex/other anterior segment surgery, rates of EK were 1.3% and 3.3% at 1 year and 2.3% and 5.6% at 8 years, respectively.

CONCLUSIONS

In a multivariate analysis, women beneficiaries are less likely to receive EK or PK for FECD compared with men, whereas non-White beneficiaries are less likely to receive EK and more likely to receive PK compared with White beneficiaries.

Cancer Risk in Patients With Fuchs Endothelial Corneal Dystrophy

PURPOSE

The purpose of this study is to quantify cancer risk in patients with Fuchs endothelial corneal dystrophy (FECD).

METHODS

Using the 2014 to 2016 Medicare Limited 5% Data Sets-Carrier Line File, US Medicare fee-for-service beneficiaries (aged 65 years or older) with FECD and cancer were identified through International Classification of Diseases , ninth and 10th Revision diagnostic codes from January 1, 2014, to December 31, 2016. The main outcome measures were odds ratios (ORs) of cancer at various anatomic locations in patients with versus without FECD.

RESULTS

Of the 1,462,740 Medicare beneficiaries, 15,534 patients (1.1%) had an International Classification of Disease code for FECD. Compared with US Medicare beneficiaries without FECD, patients with FECD were at increased risk for the following malignancies: breast [OR: 1.32; 95% confidence interval (CI): 1.22-1.43; P < 0.001], cutaneous basal cell (OR: 1.42; 95% CI: 1.35-1.49; P < 0.001), cutaneous melanoma (OR: 1.20; 95% CI: 1.03-1.40; P = 0.02), cutaneous squamous cell (OR: 1.45; 95% CI: 1.38-1.53; P < 0.001), ovarian (OR: 1.84; 95% CI: 1.48-2.30; P < 0.001), and thyroid (OR: 1.32; 95% CI: 1.04-1.68; P = 0.02). By contrast, FECD cases were at lower odds of having lung (OR: 0.81; 95% CI: 0.71-0.93; P = 0.003) and prostate cancer diagnoses (OR: 0.88; 95% CI: 0.81-0.96; P = 0.002).

CONCLUSIONS

Patients with FECD aged 65 years or older may be at increased risk for cancer at several anatomic locations. Follow-up studies are needed to further explore the association of FECD and malignancy, elucidate potential disease mechanisms, and identify genetic and/or environmental risk factors.

Comparison of TCF4 repeat expansion length in corneal endothelium and leukocytes of patients with Fuchs endothelial corneal dystrophy

Expansion of CTG trinucleotide repeats (TNR) in the transcription factor 4 (TCF4) gene is highly associated with Fuchs Endothelial Corneal Dystrophy (FECD). Due to limitations in the availability of DNA from diseased corneal endothelium, sizing of CTG repeats in FECD patients has typically been determined using DNA samples isolated from peripheral blood leukocytes. However, it is non-feasible to extract enough DNA from surgically isolated FECD corneal endothelial tissue to determine repeat length based on current technology. To circumvent this issue, total RNA was isolated from FECD corneal endothelium and sequenced using long-read sequencing. Southern blotting of DNA samples isolated from primary cultures of corneal endothelium from these same affected individuals was also assessed. Both long read sequencing and Southern blot analysis showed significantly longer CTG TNR expansion (>1000 repeats) in the corneal endothelium from FECD patients than those characterized in leukocytes from the same individuals (<90 repeats). Our findings suggest that the TCF4 CTG repeat expansions in the FECD corneal endothelium are much longer than those found in leukocytes.