Browse
Submit Data
Databases
API
Help

Dataset Information

36 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

TCF4-mediated Fuchs endothelial corneal dystrophy: Insights into a common trinucleotide repeat-associated disease.

ABSTRACT: Fuchs endothelial corneal dystrophy (FECD) is a common cause for heritable visual loss in the elderly. Since the first description of an association between FECD and common polymorphisms situated within the transcription factor 4 (TCF4) gene, genetic and molecular studies have implicated an intronic CTG trinucleotide repeat (CTG18.1) expansion as a causal variant in the majority of FECD patients. To date, several non-mutually exclusive mechanisms have been proposed that drive and/or exacerbate the onset of disease. These mechanisms include (i) TCF4 dysregulation; (ii) toxic gain-of-function from TCF4 repeat-containing RNA; (iii) toxic gain-of-function from repeat-associated non-AUG dependent (RAN) translation; and (iv) somatic instability of CTG18.1. However, the relative contribution of these proposed mechanisms in disease pathogenesis is currently unknown. In this review, we summarise research implicating the repeat expansion in disease pathogenesis, define the phenotype-genotype correlations between FECD and CTG18.1 expansion, and provide an update on research tools that are available to study FECD as a trinucleotide repeat expansion disease. Furthermore, ongoing international research efforts to develop novel CTG18.1 expansion-mediated FECD therapeutics are highlighted and we provide a forward-thinking perspective on key unanswered questions that remain in the field.

SUBMITTER: Fautsch MP

PROVIDER: S-EPMC7988464 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Effect of Trinucleotide Repeat Expansion on the Expression of TCF4 mRNA in Fuchs' Endothelial Corneal Dystrophy.

Project description:PurposeCTG trinucleotide repeat (TNR) expansion is frequently found in transcription factor 4 (TCF4) in Fuchs' endothelial corneal dystrophy (FECD), though the effect of TNR expansion on FECD pathophysiology remains unclear. The purpose of this study was to evaluate the effect of TNR expansion on TCF4 expression in corneal endothelium of patients with FECD.MethodsPeripheral blood DNA and Descemet membrane with corneal endothelium were obtained from 203 German patients with FECD. The CTG TNR repeat length in TCF4 was determined by short tandem repeat (STR) assays and Southern blotting using genomic DNA. Genotyping of rs613872 in TCF4 was performed by PCR. TCF4 mRNA levels in corneal endothelium were evaluated by quantitative PCR using three different probes. Control corneal endothelial samples were obtained from 35 non-FECD subjects.ResultsThe STR assay and Southern blotting showed that 162 of the 203 patients with FECD (80%) harbored CTG trinucleotide repeat lengths larger than 50. Quantitative PCR using all three probes demonstrated that TCF4 mRNA is significantly upregulated in the corneal endothelium of patients with FECD, regardless of the presence of TNR expansion. However, the length of the TNR tended to show a positive correlation with TCF4 expression level. No correlation was shown between the genotype of TCF4 SNP, rs613872, and the level of TCF4 expression.ConclusionsOur findings showed that TCF4 mRNA is upregulated in the corneal endothelium of patients with FECD. Further studies on the effects of TCF4 upregulation on corneal endothelial cell function will aid in understanding the pathophysiology of FECD.

| S-EPMC6392475 | biostudies-literature

Association and familial segregation of CTG18.1 trinucleotide repeat expansion of TCF4 gene in Fuchs' endothelial corneal dystrophy.

Project description:We tested the association between two intronic polymorphisms (CTG18.1 and rs613872) in TCF4 and Fuchs' endothelial corneal dystrophy (FECD), and analyzed their segregation patterns in families.We recruited 120 unrelated Caucasian subjects with FECD and 100 controls. Available family members of probands were recruited. Genotyping of the single nucleotide polymorphism (SNP) rs613872 was performed using Sanger sequencing or real-time allelic discrimination assay. The trinucleotide repeat polymorphism, CTG18.1, was genotyped using a combination of short tandem repeat assay and triplet repeat primed PCR assay. The cytosine-thymine-guanine (CTG) repeat length of ?40 was classified as an expanded CTG18.1 allele. Association of the two loci with FECD was evaluated. Segregation in 29 families was examined.The two polymorphisms are in linkage disequilibrium (r(2) = 0.65 in cases and 0.31 in controls). Significant associations were found between FECD and rs613872 (P = 3.1 × 10(-17)), expanded CTG18.1 allele (P = 6.5 × 10(-25)), and their haplotypes (P = 5.9 × 10(-19)). The odds ratio (OR) of each copy of the rs613872 G allele for FECD was estimated to be 9.5 (95% confidence interval [CI], 5.1-17.5). The OR of each copy of the CTG18.1 expanded allele was estimated to be 32.3 (95% CI, 13.4-77.6). The expanded CTG 18.1 allele cosegregated with the trait in 52% (15/29) of families with complete penetrance and 10% (3/29) with incomplete penetrance.We report, to our knowledge, the first independent replication of the expanded CTG 18.1 allele conferring significant risk for FECD (>30-fold increase). The expanded allele cosegregates with the trait with complete penetrance in a majority of families, but we also document cases of incomplete penetrance.

| S-EPMC3880006 | biostudies-literature

A common trinucleotide repeat expansion within the transcription factor 4 (TCF4, E2-2) gene predicts Fuchs corneal dystrophy.

Project description:Fuchs endothelial corneal dystrophy (FECD) is a common, familial disease of the corneal endothelium and is the leading indication for corneal transplantation. Variation in the transcription factor 4 (TCF4) gene has been identified as a major contributor to the disease. We tested for an association between an intronic TGC trinucleotide repeat in TCF4 and FECD by determining repeat length in 66 affected participants with severe FECD and 63 participants with normal corneas in a 3-stage discovery/replication/validation study. PCR primers flanking the TGC repeat were used to amplify leukocyte-derived genomic DNA. Repeat length was determined by direct sequencing, short tandem repeat (STR) assay and Southern blotting. Genomic Southern blots were used to evaluate samples for which only a single allele was identified by STR analysis. Compiling data for 3 arms of the study, a TGC repeat length >50 was present in 79% of FECD cases and in 3% of normal controls cases (p<0.001). Among cases, 52 of 66 (79%) subjects had >50 TGC repeats, 13 (20%) had <40 repeats and 1 (2%) had an intermediate repeat length. In comparison, only 2 of 63 (3%) unaffected control subjects had >50 repeats, 60 (95%) had <40 repeats and 1 (2%) had an intermediate repeat length. The repeat length was greater than 1000 in 4 FECD cases. The sensitivity and specificity of >50 TGC repeats identifying FECD in this patient cohort was 79% and 96%, respectively Expanded TGC repeat was more specific for FECD cases than the previously identified, highly associated, single nucleotide polymorphism, rs613872 (specificity = 79%). The TGC trinucleotide repeat expansion in TCF4 is strongly associated with FECD, and a repeat length >50 is highly specific for the disease This association suggests that trinucleotide expansion may play a pathogenic role in the majority of FECD cases and is a predictor of disease risk.

| S-EPMC3504061 | biostudies-literature

Trinucleotide repeat expansion in the transcription factor 4 (TCF4) gene in Thai patients with Fuchs endothelial corneal dystrophy.

Project description:PurposeTo evaluate the association of single nucleotide polymorphisms (SNPs) and the intronic expansion of a trinucleotide repeat (TNR) in the TCF4 gene with Fuchs endothelial corneal dystrophy (FECD) in a Thai population.MethodsIn total, 54 Thai FECD patients and 54 controls were recruited for the study. Five SNPs (rs613872, rs2123392, rs17089887, rs1452787, and rs1348047), previously reported to be associated with FECD, were genotyped by direct sequencing. The repeat length was determined by direct sequencing of PCR-amplified DNA (a short tandem repeat; STR assay) and by triplet repeat primed PCR (TP-PCR).ResultsOnly one of the 54 patients with FECD harboured rs613872 (1.9%). Four SNPs (rs2123392, rs17089887, rs1452787, and rs1348047), which are not rare polymorphisms in the Thai population, were found in approximately half of the patients. Of the 54 patients, 21 (1 homozygous and 20 heterozygous patients; 39%) harboured a TNR ≥ 40, while 33 patients (61%) harboured a TNR < 40.ConclusionsThe association of TNR expansion in TCF4 with FECD is shown for the first time in the Thai population. The intronic TNR expansion identified in various ethnic groups underlines the importance of expansion as a potent pathophysiological cause of FECD.

| S-EPMC7182560 | biostudies-literature

Gene Expression and Missplicing in the Corneal Endothelium of Patients With a TCF4 Trinucleotide Repeat Expansion Without Fuchs' Endothelial Corneal Dystrophy.

Project description:PurposeCTG trinucleotide repeat (TNR) expansion in an intron of the TCF4 gene is the most common genetic variant associated with Fuchs' endothelial corneal dystrophy (FECD). Although several mechanisms have been implicated in the disease process, their exact pathophysiologic importance is unclear. To understand events leading from TCF4 TNR expansion to disease phenotype, we characterized splicing, gene expression, and exon sequence changes in a rare cohort of patients with TNR expansions but no phenotypic FECD (RE+/FECD-).MethodsCorneal endothelium and blood were collected from patients undergoing endothelial keratoplasty for non-FECD corneal edema. Total RNA was isolated from corneal endothelial tissue (n = 3) and used for RNASeq. Gene splicing and expression was assessed by Mixture of Isoforms (MISO) and MAP-RSeq software. Genomic DNA was isolated from blood mononuclear cells and used for whole genome exome sequencing. Base calling was performed using Illumina's Real-Time Analysis.ResultsThree genes (MBNL1, KIF13A, AKAP13) that were previously identified as misspliced in patients with a CTG TNR expansion and FECD disease (RE+/FECD+) were found normally spliced in RE+/FECD- samples. Gene expression differences in pathways associated with the innate immune response, cell signaling (e.g., TGFβ, WNT), and cell senescence markers were also identified between RE+/FECD- and RE+/FECD+ groups. No consistent genetic variants were identified in RE+/FECD- patient exomes.ConclusionsIdentification of novel splicing patterns and differential gene expression in RE+/FECD- samples provides new insights and more relevant gene targets that may be protective against FECD disease in vulnerable patients with TCF4 CTG TNR expansions.

| S-EPMC6716950 | biostudies-literature

Association of rs613872 and Trinucleotide Repeat Expansion in the TCF4 Gene of German Patients With Fuchs Endothelial Corneal Dystrophy.

Project description:PurposeTo investigate single nucleotide polymorphisms (SNPs) and trinucleotide repeat (TNR) expansion in the transcription factor 4 (TCF4) gene in a large cohort of German patients with Fuchs endothelial corneal dystrophy (FECD).MethodsGenomic DNA was obtained from 398 patients with FECD and from 58 non-FECD controls. Thirty-seven previously reported SNPs were evaluated by genotyping. The 398 FECD samples were analyzed for TNR expansions by short tandem repeat assays and Southern blotting. The possible associations between the TNR length and clinical parameters (age, sex, visual acuity, and central corneal thickness) were analyzed in 132 patients.ResultsThe SNPs in COL8A2, TCF8, LOXHD1, and AGBL1 showed no heterogeneity in 36 cases, although SLCA411 showed 3 nonsense mutations. SNPs were detected for TCF4 (rs613872, rs2123392, rs17089887, rs1452787, and rs1348047), but only rs613872 showed a significant association with FECD (P = 9.93 × 10). Overall, 315/398 (79%) patients harbored TNR lengths >50, whereas no non-FECD controls harbored TNR lengths >50. The TCF4 SNP rs613872 genotype was TT: 39 (67%), TG: 18 (31%), and GG: 1 (2%) in non-FECD controls; TT: 39 (47%), TG: 38 (46%), and GG: 6 (7%) in FECD cases harboring TNR <50; and TT: 23 (8%), TG: 224 (79%), and GG: 38 (13%) in FECD cases harboring TNR >50 (P = 2.93 × 10). No significant association was detected between the TNR length and clinical parameters.ConclusionsOur large German cohort demonstrated a significant association between the risk allele G in rs613872 and FECD, irrespective of TNR expansion, although this risk allele was more frequent in FECD cases with TNR expansion than without.

| S-EPMC6554040 | biostudies-literature

Expansion of CTG18.1 Trinucleotide Repeat in TCF4 Is a Potent Driver of Fuchs' Corneal Dystrophy.

Project description:PurposeTo analyze the expansion of CTG18.1 allele associated with Fuchs' corneal dystrophy (FCD) in our large cohort of late-onset FCD cases.MethodsCTG repeats within the CTG18.1 allele were estimated by short tandem repeat (STR) and triplet primed PCR (TP-PCR) assays in our large cohort of 574 late-onset FCD cases and 354 controls and large multigeneration familial cases. The age versus severity relationships were analyzed in FCD genotypes, namely, nonexpanded (N/N), monoallelic expansion (N/X), and biallelic expansion (X/X) with N ≤ 40 CTG monomers. The threshold for causality conferred by an expansion of CTG18.1 was identified by excluding the population of FCD cases who harbored an allele length equivalent to the maximum CTG monomers observed in the controls.ResultsThe expanded CTG18.1 for (CTG)n>40 showed a strong association (P = 1.56 × 10(-82)) with FCD. Importantly, we delineated the threshold of expansion to 103 CTG repeats above which the allele confers causality in 17.8% of FCD cases. Regression analyses demonstrated a significant correlation between disease severity and age in individuals who harbor either a monoallelic expansion or a biallelic expansion at (CTG) n > 40. These analyses helped predict FCD in two previously unaffected individuals based on their CTG18.1 expansion genotype.ConclusionsA monoallelic expansion of CTG18.1 contributes to increased disease severity and is causal at (CTG)n>103, whereas a biallelic expansion is sufficient to be causal for FCD at (CTG)n>40. This study highlights the largest contributory causal allele for FCD.

| S-EPMC4515948 | biostudies-literature

Gene expression in the corneal endothelium of Fuchs endothelial corneal dystrophy patients with and without expansion of a trinucleotide repeat in TCF4.

Project description:Fuchs Endothelial Corneal Dystrophy (FECD) is a late onset, autosomal dominant eye disease that can lead to loss of vision. Expansion of a CTG trinucleotide repeat in the third intron of the transcription factor 4 (TCF4) gene is highly associated with FECD. However, only about 75% of FECD patients in the northern European population possess an expansion of this repeat. The remaining FECD cases appear to be associated with variants in other genes. To better understand the pathophysiology of this disease, we compared gene expression profiles of corneal endothelium from FECD patients with an expanded trinucleotide repeat (RE+) to those that do not have a repeat expansion (RE-). Comparative analysis of these two cohorts showed widespread RNA mis-splicing in RE+, but not in RE- samples. Quantitatively, we identified 39 genes in which expression was significantly different between RE+ and RE- samples. Examination of the mutation profiles in the RE- samples did not find any mutations in genes previously associated with FECD, but did reveal one sample with a rare variant of laminin subunit gamma 1 (LAMC1) and three samples with rare variants in the gene coding for the mitochondrial protein peripheral-type benzodiazepine receptor-associated protein 1 (TSPOAP1).

| S-EPMC6028112 | biostudies-literature

Amplification-free long-read sequencing of TCF4 expanded trinucleotide repeats in Fuchs Endothelial Corneal Dystrophy.

Project description:Amplification of a CAG trinucleotide motif (CTG18.1) within the TCF4 gene has been strongly associated with Fuchs Endothelial Corneal Dystrophy (FECD). Nevertheless, a small minority of clinically unaffected elderly patients who have expanded CTG18.1 sequences have been identified. To test the hypothesis that the CAG expansions in these patients are protected from FECD because they have interruptions within the CAG repeats, we utilized a combination of an amplification-free, long-read sequencing method and a new target-enrichment sequence analysis tool developed by Pacific Biosciences to interrogate the sequence structure of expanded repeats. The sequencing was successful in identifying a previously described interruption within an unexpanded allele and provided sequence data on expanded alleles greater than 2000 bases in length. The data revealed considerable heterogeneity in the size distribution of expanded repeats within each patient. Detailed analysis of the long sequence reads did not reveal any instances of interruptions to the expanded CAG repeats, but did reveal novel variants within the AGG repeats that flank the CAG repeats in two of the five samples from clinically unaffected patients with expansions. This first examination of the sequence structure of CAG repeats in CTG18.1 suggests that factors other than interruptions to the repeat structure account for the absence of disease in some elderly patients with repeat expansions in the TCF4 gene.

| S-EPMC6611681 | biostudies-literature

Trinucleotide Repeat-Targeting dCas9 as a Therapeutic Strategy for Fuchs' Endothelial Corneal Dystrophy.

Project description:PurposeFuchs' endothelial corneal dystrophy (FECD) is the leading indication for corneal transplantation. Seventy percent of cases are caused by an intronic CTG triplet repeat expansion in the TCF4 gene that results in accumulation of pathogenic expanded CUG repeat RNA (CUGexp) as nuclear foci in corneal endothelium. A catalytically dead Cas9 (dCas9) can serve as an effective guide to target genomic DNA or RNA transcripts. Here, we examined the utility of the clustered regularly interspaced short palindromic repeats (CRISPR)-dCas9 system to effectively target and reduce CUGexp.MethodsWe delivered dCas9 and repeat-targeting single guide RNA (sgRNA) expression plasmids to patient-derived endothelial cells using lipofection or lentiviral transduction. We used fluorescence in situ hybridization (FISH) and RNA dot-blot hybridization to quantify CUGexp foci and repeat RNA levels, respectively. TCF4 expression levels were assessed using quantitative PCR (qPCR).ResultsUsing FISH, we found that expression of both dCas9 and a (CAG)n sgRNA complementary to CUGexp are necessary to reduce foci. We observed a reduction in percentage of cells with foci from 59% to 5.6% and number of foci per 100 cells from 73.4 to 7.45 (P < 0.001) in cells stably expressing dCas9-(CAG)n sgRNA but saw no decrease in cells expressing dCas9-(CUG)n sgRNA or nontargeting control sgRNA. In cells with dCas9-(CAG)n sgRNA, we detected a reduction in CUGexp RNA by dot-blot without any reduction in TCF4 mRNA levels using qPCR.ConclusionsUsing CRISPR-dCas9 to target the trinucleotide repeat is a promising treatment for FECD contingent on effective in vivo delivery.Translational relevanceThis work advances a gene therapy for a common age-related degenerative disorder.

| S-EPMC7463221 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data