Name of the disease (synonyms) CUGC for posterior polymorphous corneal dystrophy (PPCD).OMIM# of the disease 122000; 609141; 618031.Name of the analysed genes or DNA/chromosome segments OVOL2 (PPCD1); ZEB1 (PPCD3); GRHL2 (PPCD4).OMIM# of the gene(s) 616441; 189909; 608576. Review of the analytical and clinical validity as well as of the clinical utility of DNA-based testing for variants in theOVOL2, ZEB1andGRHL2gene(s) in a diagnostic setting, predictive and parental settings and for risk assesment in relatives.

• MeSH
• Corneal Dystrophies, Hereditary diagnosis   genetics   MeSH
• DNA-Binding Proteins genetics   MeSH
• Genetic Testing methods   standards   MeSH
• Humans MeSH
• Sensitivity and Specificity MeSH
• Practice Guidelines as Topic MeSH
• Zinc Finger E-box-Binding Homeobox 1 genetics   MeSH
• Transcription Factors genetics   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• DNA-Binding Proteins MeSH
• GRHL2 protein, human MeSH Browser
• Ovol2 protein, human MeSH Browser
• Zinc Finger E-box-Binding Homeobox 1 MeSH
• Transcription Factors MeSH
• ZEB1 protein, human MeSH Browser

A substantial proportion of patients with posterior polymorphous corneal dystrophy (PPCD) lack a molecular diagnosis. We evaluated 14 unrelated probands who had a clinical diagnosis of PPCD who were previously determined to be negative for mutations in ZEB1 by direct sequencing. A combination of techniques was used including whole-exome sequencing (WES), single-nucleotide polymorphism (SNP) array copy number variation (CNV) analysis, quantitative real-time PCR, and long-range PCR. Segregation of potentially pathogenic changes with disease was confirmed, where possible, in family members. A putative run of homozygosity on chromosome 10 was identified by WES in a three-generation PPCD family, suggestive of a heterozygous deletion. SNP array genotyping followed by long-range PCR and direct sequencing to define the breakpoints confirmed the presence of a large deletion that encompassed multiple genes, including ZEB1. Identification of a heterozygous deletion spanning ZEB1 prompted us to further investigate potential CNVs at this locus in the remaining probands, leading to detection of two additional heterozygous ZEB1 gene deletions. This study demonstrates that ZEB1 mutations account for a larger proportion of PPCD than previously estimated, and supports the hypothesis that haploinsufficiency of ZEB1 is the underlying molecular mechanism of disease for PPCD3.

• MeSH
• Corneal Dystrophies, Hereditary genetics   pathology   MeSH
• Gene Deletion * MeSH
• Child MeSH
• Adult MeSH
• Haploinsufficiency * MeSH
• Heterozygote MeSH
• Polymorphism, Single Nucleotide MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Pedigree MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Zinc Finger E-box-Binding Homeobox 1 genetics   MeSH
• DNA Copy Number Variations MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Zinc Finger E-box-Binding Homeobox 1 MeSH
• ZEB1 protein, human MeSH Browser

Congenital hereditary endothelial dystrophy 1 (CHED1) and posterior polymorphous corneal dystrophy 1 (PPCD1) are autosomal-dominant corneal endothelial dystrophies that have been genetically mapped to overlapping loci on the short arm of chromosome 20. We combined genetic and genomic approaches to identify the cause of disease in extensive pedigrees comprising over 100 affected individuals. After exclusion of pathogenic coding, splice-site, and copy-number variations, a parallel approach using targeted and whole-genome sequencing facilitated the identification of pathogenic variants in a conserved region of the OVOL2 proximal promoter sequence in the index families (c.-339_361dup for CHED1 and c.-370T>C for PPCD1). Direct sequencing of the OVOL2 promoter in other unrelated affected individuals identified two additional mutations within the conserved proximal promoter sequence (c.-274T>G and c.-307T>C). OVOL2 encodes ovo-like zinc finger 2, a C2H2 zinc-finger transcription factor that regulates mesenchymal-to-epithelial transition and acts as a direct transcriptional repressor of the established PPCD-associated gene ZEB1. Interestingly, we did not detect OVOL2 expression in the normal corneal endothelium. Our in vitro data demonstrate that all four mutated OVOL2 promoters exhibited more transcriptional activity than the corresponding wild-type promoter, and we postulate that the mutations identified create cryptic cis-acting regulatory sequence binding sites that drive aberrant OVOL2 expression during endothelial cell development. Our data establish CHED1 and PPCD1 as allelic conditions and show that CHED1 represents the extreme of what can be considered a disease spectrum. They also implicate transcriptional dysregulation of OVOL2 as a common cause of dominantly inherited corneal endothelial dystrophies.

• MeSH
• Alleles * MeSH
• Corneal Dystrophies, Hereditary genetics   MeSH
• DNA MeSH
• Humans MeSH
• Mutation * MeSH
• Promoter Regions, Genetic * MeSH
• Pedigree MeSH
• Base Sequence MeSH
• Sequence Homology, Nucleic Acid MeSH
• Transcription Factors genetics   MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• DNA MeSH
• Ovol2 protein, human MeSH Browser
• Transcription Factors MeSH

Posterior polymorphous corneal dystrophy (PPCD) is a rare autosomal dominant genetically heterogeneous disorder. Nineteen Czech PPCD pedigrees with 113 affected family members were identified, and 17 of these kindreds were genotyped for markers on chromosome 20p12.1- 20q12. Comparison of haplotypes in 81 affected members, 20 unaffected first degree relatives and 13 spouses, as well as 55 unrelated controls, supported the hypothesis of a shared ancestor in 12 families originating from one geographic location. In 38 affected individuals from nine of these pedigrees, a common haplotype was observed between D20S48 and D20S107 spanning approximately 23 Mb, demonstrating segregation of disease with the PPCD1 locus. This haplotype was not detected in 110 ethnically matched control chromosomes. Within the common founder haplotype, a core mini-haplotype was detected for D20S605, D20S182 and M189K2 in all 67 affected members from families 1-12, however alleles representing the core mini-haplotype were also detected in population matched controls. The most likely location of the responsible gene within the disease interval, and estimated mutational age, were inferred by linkage disequilibrium mapping (DMLE+2.3). The appearance of a disease-causing mutation was dated between 64-133 generations. The inferred ancestral locus carrying a PPCD1 disease-causing variant within the disease interval spans 60 Kb on 20p11.23, which contains a single known protein coding gene, ZNF133. However, direct sequence analysis of coding and untranslated exons did not reveal a potential pathogenic mutation. Microdeletion or duplication was also excluded by comparative genomic hybridization using a dense chromosome 20 specific array. Geographical origin, haplotype and statistical analysis suggest that in 14 unrelated families an as yet undiscovered mutation on 20p11.23 was inherited from a common ancestor. Prevalence of PPCD in the Czech Republic appears to be the highest worldwide and our data suggests that at least one other novel locus for PPCD also exists.

• MeSH
• Corneal Dystrophies, Hereditary epidemiology   genetics   pathology   MeSH
• Genes, Dominant MeSH
• Founder Effect * MeSH
• Exons MeSH
• Genetic Heterogeneity MeSH
• Genetic Loci MeSH
• Haplotypes MeSH
• Humans MeSH
• Chromosomes, Human, Pair 20 * MeSH
• Chromosome Mapping MeSH
• Mutation * MeSH
• Prevalence MeSH
• Repressor Proteins genetics   MeSH
• Pedigree MeSH
• Cornea metabolism   pathology   MeSH
• Comparative Genomic Hybridization MeSH
• Case-Control Studies MeSH
• Linkage Disequilibrium * MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Names of Substances
• Repressor Proteins MeSH
• ZNF133 protein, human MeSH Browser

Posterior polymorphous corneal dystrophy (PPCD) is a rare, bilateral autosomal dominant disorder affecting primarily the corneal endothelium and descemet membrane (DM). The aim of this study was to establish the origin of abnormal endothelium in a patient with PPCD exhibiting cornea graft failure after keratoplasty surgery. A sex-mismatched graft obtained from a patient with PPCD who underwent repeat penetrating keratoplasty and the patient's original cornea were investigated. Combined fluorescent immunohistochemistry for cytokeratin (CK) 19 (a marker of aberrant PPCD endothelium) with fluorescence in situ hybridization (FISH) of the sex chromosomes were used in order to characterize the cells on the posterior graft surface. The pathological endothelium of the failed PPCD cornea revealed strong positivity for CK19 using fluorescent immunohistochemistry. In all the CK19-positive cells, both X and Y chromosomes were simultaneously detected using FISH. The results clearly showed the original cells of the patient (XY), within 3.5 years, almost totally overgrown the posterior corneal surface of the graft (XX). Moreover, an abnormal posterior collagenous layer populated by fibroblast-like cells was observed between DM and the endothelium in the failed graft, but its exact origin could not be established due to the low number of cells. Simultaneous detection of CK19 using fluorescent immunohistochemistry together with the detection of gonosomes using FISH was performed for the first time in the cornea and allowed us to prove that the recurrence of PPCD was caused by pathological abnormal proliferation and migration of recipient cells into donor graft.

• MeSH
• Corneal Dystrophies, Hereditary genetics   pathology   MeSH
• Descemet Membrane pathology   MeSH
• In Situ Hybridization, Fluorescence MeSH
• Keratins metabolism   MeSH
• Middle Aged MeSH
• Humans MeSH
• Chromosomes, Human, X MeSH
• Chromosomes, Human, Y MeSH
• Endothelium, Corneal cytology   metabolism   pathology   MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Keratins MeSH

We describe the search for mutations in six unrelated Czech and four unrelated British families with posterior polymorphous corneal dystrophy (PPCD); a relatively rare eye disorder. Coding exons and intron/exon boundaries of all three genes (VSX1, COL8A2, and ZEB1/TCF8) previously reported to be implicated in the pathogenesis of this disorder were screened by DNA sequencing. Four novel pathogenic mutations were identified in four families; two deletions, one nonsense, and one duplication within exon 7 in the ZEB1 gene located at 10p11.2. We also genotyped the Czech patients to test for a founder haplotype and lack of disease segregation with the 20p11.2 locus we previously described. Although a systematic clinical examination was not performed, our investigation does not support an association between ZEB1 changes and self reported non-ocular anomalies. In the remaining six families no disease causing mutations were identified thereby indicating that as yet unidentified gene(s) are likely to be responsible for PPCD.

• MeSH
• Corneal Dystrophies, Hereditary genetics   MeSH
• Adult MeSH
• Homeodomain Proteins genetics   MeSH
• Collagen Type VIII genetics   MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Mutation * MeSH
• DNA Mutational Analysis MeSH
• Eye Proteins genetics   MeSH
• Pedigree MeSH
• Aged MeSH
• Zinc Finger E-box-Binding Homeobox 1 MeSH
• Transcription Factors genetics   MeSH
• Rare Diseases genetics   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic MeSH
• United Kingdom MeSH
• Names of Substances
• COL8A2 protein, human MeSH Browser
• Homeodomain Proteins MeSH
• Collagen Type VIII MeSH
• Eye Proteins MeSH
• Zinc Finger E-box-Binding Homeobox 1 MeSH
• Transcription Factors MeSH
• VSX1 protein, human MeSH Browser
• ZEB1 protein, human MeSH Browser