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The forkhead transcription factor FOXE3 is critical for vertebrate eye development. Recessive and dominant variants cause human ocular disease but the full range of phenotypes and mechanisms of action for the two classes of variants are unknown. We identified FOXE3 variants in individuals with congenital eye malformations and carried out in vitro functional analysis on selected alleles. Sixteen new recessive and dominant families, including six novel variants, were identified. Analysis of new and previously reported genetic and clinical data demonstrated a broad phenotypic range with an overlap between recessive and dominant disease. Most families with recessive alleles, composed of truncating and forkhead-domain missense variants, had severe corneal opacity (90%; sclerocornea in 47%), aphakia (83%) and microphthalmia (80%), but some had milder features including isolated cataract. The phenotype was most variable for recessive missense variants, suggesting that the functional consequences may be highly dependent on the type of amino acid substitution and its position. When assessed, aniridia or iris hypoplasia were noted in 89% and optic nerve anomalies in 60% of recessive cases, indicating that these defects are also common and may be underrecognized. In dominant pedigrees, caused by extension variants, normal eye size (96%), cataracts (99%) and variable anterior segment anomalies were seen in most, but some individuals had microphthalmia, aphakia or sclerocornea, more typical of recessive disease. Functional studies identified variable effects on the protein stability, DNA binding, nuclear localization and transcriptional activity for recessive FOXE3 variants, whereas dominant alleles showed severe impairment in all areas and dominant-negative characteristics.

Cullin 4B (CUL4B), lysosomal-associated membrane protein Type 2 (LAMP2), ATP1B4, TMEM255A, and ZBTB33 are neighboring genes on Xq24. Mutations in CUL4B result in Cabezas syndrome (CS). Male CS patients present with dysmorphic, neuropsychiatric, genitourinary, and endocrine abnormalities. Heterozygous CS females are clinically asymptomatic. LAMP2 mutations cause Danon disease (DD). Cardiomyopathy is a dominant feature of DD present in both males and heterozygous females. No monogenic phenotypes have been associated with mutations in ATP1B4, TMEM255A, and ZBTB33 genes. To facilitate diagnostics and counseling in CS and DD families, we present a female DD patient with a de novo Alu-mediated Xq24 rearrangement causing a deletion encompassing CUL4B, LAMP2, and also the other three neighboring genes. Typical to females heterozygous for CUL4B mutations, the patient was CS asymptomatic, however, presented with extremely skewed X-chromosome inactivation (XCI) ratios in peripheral white blood cells. As a result of the likely selection against CUL4B deficient clones, only minimal populations (~3%) of LAMP2 deficient leukocytes were identified by flow cytometry. On the contrary, myocardial LAMP2 protein expression suggested random XCI. We demonstrate that contiguous CUL4B and LAMP2 loss-of-function copy number variations occur and speculate that male patients carrying similar defects could present with features of both CS and DD.

Purpose To demonstrate the utility of an amplification-free long-read sequencing method to characterize the Fuchs endothelial corneal dystrophy (FECD)-associated intronic TCF4 triplet repeat (CTG18.1). Methods We applied an amplification-free method, utilizing the CRISPR/Cas9 system, in combination with PacBio single-molecule real-time (SMRT) long-read sequencing, to study CTG18.1. FECD patient samples displaying a diverse range of CTG18.1 allele lengths and zygosity status (n = 11) were analyzed. A robust data analysis pipeline was developed to effectively filter, align, and interrogate CTG18.1-specific reads. All results were compared with conventional polymerase chain reaction (PCR)-based fragment analysis. Results CRISPR-guided SMRT sequencing of CTG18.1 provided accurate genotyping information for all samples and phasing was possible for 18/22 alleles sequenced. Repeat length instability was observed for all expanded (≥50 repeats) phased CTG18.1 alleles analyzed. Furthermore, higher levels of repeat instability were associated with increased CTG18.1 allele length (mode length ≥91 repeats) indicating that expanded alleles behave dynamically. Conclusion CRISPR-guided SMRT sequencing of CTG18.1 has revealed novel insights into CTG18.1 length instability. Furthermore, this study provides a framework to improve the molecular diagnostic accuracy for CTG18.1-mediated FECD, which we anticipate will become increasingly important as gene-directed therapies are developed for this common age-related and sight threatening disease.

The aim of this study was to identify the molecular genetic cause of disease in posterior polymorphous corneal dystrophy (PPCD) probands of diverse origin and to assess the utility of massively parallel sequencing in the detection of ZEB1 mutations. We investigated a total of 12 families (five British, four Czech, one Slovak and two Swiss). Ten novel and two recurrent disease-causing mutations in ZEB1, were identified in probands by Sanger (n = 5), exome (n = 4) and genome (n = 3) sequencing. Sanger sequencing was used to confirm the mutations detected by massively parallel sequencing, and to perform segregation analysis. Genome sequencing revealed that one proband harboured a novel ∼0.34 Mb heterozygous de novo deletion spanning exons 1-7 and part of exon 8. Transcript analysis confirmed that the ZEB1 transcript is detectable in blood-derived RNA samples and that the disease-associated variant c.482-2A>G leads to aberrant pre-mRNA splicing. De novo mutations, which are a feature of PPCD3, were found in the current study with an incidence rate of at least 16.6%. In general, massively parallel sequencing is a time-efficient way to detect PPCD3-associated mutations and, importantly, genome sequencing enables the identification of full or partial heterozygous ZEB1 deletions that can evade detection by both Sanger and exome sequencing. These findings contribute to our understanding of PPCD3, for which currently, 49 pathogenic variants have been identified, all of which are predicted to be null alleles.

A bilaterally blind woman, with a three generation family history of autosomal dominant congenital cataracts, variably associated with iris colobomata and microcornea, sought preconception genetic consultation. Whole-exome sequencing was performed in three affected family members, one unaffected first degree relative, and one spouse. The sequence variant c.168CG; p.(Tyr56∗) in CRYGD, previously reported as pathogenic, and a novel mutation c.809CA; p.(Ser270Tyr) in MAF, were identified in two affected family members; the grandmother, and half-brother of the proband. The proband inherited only the MAF mutation, whereas her clinically unaffected sister had the CRYGD change. In silico analysis supported a pathogenic role of p.(Ser270Tyr) in MAF, which was absent from publicly available whole-exome datasets, and 1161 Czech individuals. The frequency of CRYGD p.(Tyr56∗) in the ExAC dataset was higher than the estimated incidence of congenital cataract in the general population. Our study highlights that patients with genetically heterogeneous conditions may exhibit rare variants in more than one disease-associated gene, warranting caution with data interpretation, and supporting parallel screening of all genes known to harbour pathogenic mutations for a given phenotype. The pathogenicity of sequence variants previously reported as cataract-causing may require re-assessment in light of recently released datasets of human genomic variation.

Purpose: Missing heritability in human diseases represents a major challenge, and this is particularly true for ABCA4-associated Stargardt disease (STGD1). We aimed to elucidate the genomic and transcriptomic variation in 1054 unsolved STGD and STGD-like probands. Methods: Sequencing of the complete 128-kb ABCA4 gene was performed using single-molecule molecular inversion probes (smMIPs), based on a semiautomated and cost-effective method. Structural variants (SVs) were identified using relative read coverage analyses and putative splice defects were studied using in vitro assays. Results: In 448 biallelic probands 14 known and 13 novel deep-intronic variants were found, resulting in pseudoexon (PE) insertions or exon elongations in 105 alleles. Intriguingly, intron 13 variants c.1938-621G>A and c.1938-514G>A resulted in dual PE insertions consisting of the same upstream, but different downstream PEs. The intron 44 variant c.6148-84A>T resulted in two PE insertions and flanking exon deletions. Eleven distinct large deletions were found, two of which contained small inverted segments. Uniparental isodisomy of chromosome 1 was identified in one proband. Conclusion: Deep sequencing of ABCA4 and midigene-based splice assays allowed the identification of SVs and causal deep-intronic variants in 25% of biallelic STGD1 cases, which represents a model study that can be applied to other inherited diseases. Fil: Khan, Mubeen. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Cornelis, Stéphanie S.. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Del Pozo Valero, Marta. Hospital Universitario Fundación Jiménez Díaz; España. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Whelan, Laura. Trinity College; Estados Unidos Fil: Runhart, Esmee H.. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Mishra, Ketan. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Bults, Femke. Radboud University Nijmegen Medical Centre; Países Bajos Fil: AlSwaiti, Yahya. St John of Jerusalem Eye Hospital Group; Palestina (ANP) Fil: AlTalbishi, Alaa. St John of Jerusalem Eye Hospital Group; Palestina (ANP) Fil: De Baere, Elfride. University of Ghent; Bélgica Fil: Banfi, Sandro. Seconda Universita Degli Studi Di Napoli; Italia Fil: Banin, Eyal. The Hebrew University of Jerusalem; Israel Fil: Bauwens, Miriam. University of Ghent; Bélgica Fil: Ben Yosef, Tamar. The Ruth And Bruce Rappaport Faculty Of Medicine; Israel Fil: Boon, Camiel J. F.. Leiden University. Leiden University Medical Center; Países Bajos Fil: van den Born, L. Ingeborgh. Rotterdam Ophthalmic Institute; Países Bajos Fil: Defoort, Sabine. Universite Lille; Francia Fil: Devos, Aurore. Universite Lille; Francia Fil: Dockery, Adrian. Trinity College; Estados Unidos Fil: Dudakova, Lubica. Charles University and General University Hospital; República Checa Fil: Fakin, Ana. Charles University and General University Hospital; República Checa Fil: Farrar, G. Jane. Trinity College; Estados Unidos Fil: Ferraz Sallum, Juliana Maria. Universidade Federal de Sao Paulo; Brasil Fil: Fujinami, Kaoru. UCL Institute of Ophthalmology; Reino Unido Fil: Gilissen, Christian. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Glavac, Damjan. University of Ljubljana; Eslovenia Fil: Gorin, Michael B.. University of California at Los Angeles. School of Medicine; Estados Unidos Fil: Greenberg, Jacquie. University of Cape Town; Sudáfrica Fil: Hayashi, Takaaki. The Jikei University School of Medicine; Japón Fil: Hettinga, Ymkje M.. Bartiméus Diagnostic Center for Complex Visual Disorders; Países Bajos Fil: Hoischen, Alexander. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Hoyng, Carel B.. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Hufendiek, Karsten. University Eye Hospital Hannover Medical School; Alemania Fil: Jägle, Herbert. University Regensburg; Alemania Fil: Kamakari, Smaragda. OMMA Ophthalmological Institute of Athens; Grecia Fil: Karali, Marianthi. Seconda Universita Degli Studi Di Napoli; Italia Fil: Kellner, Ulrich. No especifíca; Fil: Klaver, Caroline C. W.. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Kousal, Bohdan. Charles University and General University Hospital; República Checa Fil: Lamey, Tina M.. University of Western Australia; Australia Fil: MacDonald, Ian M.. University of Alberta; Canadá Fil: Matynia, Anna. University of California at Los Angeles. School of Medicine; Estados Unidos Fil: McLaren, Terri L.. University of Western Australia; Australia Fil: Mena, Marcela D.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: Meunier, Isabelle. Université Montpellier II; Francia Fil: Miller, Rianne. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Newman, Hadas. Universitat Tel Aviv; Israel Fil: Ntozini, Buhle. University of Cape Town; Sudáfrica Fil: Oldak, Monika. No especifíca; Fil: Pieterse, Marc. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Podhajcer, Osvaldo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: Puech, Bernard. Universite Lille; Francia Fil: Ramesar, Raj. University of Cape Town; Sudáfrica Fil: Rüther, Klaus. No especifíca; Fil: Salameh, Manar. No especifíca; Fil: Salles, Mariana Vallim. Universidade de Sao Paulo; Brasil Fil: Sharon, Dror. The Hebrew University of Jerusalem; Israel Fil: Simonelli, Francesca. Seconda Universita Degli Studi Di Napoli; Italia Fil: Spital, Georg. No especifíca; Fil: Steehouwer, Marloes. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Szaflik, Jacek P.. No especifíca; Fil: Thompson, Jennifer A.. No especifíca; Fil: Thuillier, Caroline. Universite Lille; Francia Fil: Tracewska, Anna M.. No especifíca; Fil: van Zweeden, Martine. Radboud University Nijmegen Medical Centre; Países Bajos Fil: Vincent, Andrea L.. University of Auckland; Nueva Zelanda Fil: Zanlonghi, Xavier. No especifíca; Fil: Liskova, Petra. Charles University and General University Hospital; República Checa Fil: Stöhr, Heidi. Universitat Regensburg; Alemania Fil: De Roach, John N.. University of Western Australia; Australia Fil: Ayuso, Carmen. Hospital Universitario Fundación Jiménez Díaz; España Fil: Roberts, Lisa. University of Cape Town; Sudáfrica Fil: Weber, Bernhard H. F.. Universitat Regensburg; Alemania Fil: Dhaenens, Claire Marie. Universite Lille; Francia Fil: Cremers, Frans P. M.. Radboud University Nijmegen Medical Centre; Países Bajos

Background: Congenital cataract is the most common cause of blindness in the world. Congenital cataracts are clinically and genetically heterogeneous and are mostly inherited in an autosomal dominant fashion. We identified the genetic cause of isolated autosomal dominant cataract in a four-generation British family and a Czech family. Methods: Whole exome sequencing (WES) was performed on one affected member in the British family and two affected members in the Czech family. Results: A novel missense variant c.388C > T; p.(R130C) was identified in the Lens integral membrane protein (LIM2) and found to co-segregate with disease in both families. Conclusions: Here we report the first autosomal dominant congenital cataract variant p.(R130C) in LIM2, causing a non-syndromic pulverulent and nuclear phenotype in European families.

Missing heritability in human diseases represents a major challenge. Although whole-genome sequencing enables the analysis of coding and non-coding sequences, substantial costs and data storage requirements hamper its large-scale use to (re)sequence genes in genetically unsolved cases. The ABCA4 gene implicated in Stargardt disease (STGD1) has been studied extensively for 22 years, but thousands of cases remained unsolved. Therefore, single molecule molecular inversion probes were designed that enabled an automated and cost-effective sequence analysis of the complete 128-kb ABCA4 gene. Analysis of 1,054 unsolved STGD and STGD-like probands resulted in bi-allelic variations in 448 probands. Twenty-seven different causal deep-intronic variants were identified in 117 alleles. Based on in vitro splice assays, the 13 novel causal deep-intronic variants were found to result in pseudo-exon (PE) insertions (n=10) or exon elongations (n=3). Intriguingly, intron 13 variants c.1938-621G>A and c.1938-514G>A resulted in dual PE insertions consisting of the same upstream, but different downstream PEs. The intron 44 variant c.6148-84A>T resulted in two PE insertions that were accompanied by flanking exon deletions. Structural variant analysis revealed 11 distinct deletions, two of which contained small inverted segments. Uniparental isodisomy of chromosome 1 was identified in one proband. Integrated complete gene sequencing combined with transcript analysis, identified pathogenic deep-intronic and structural variants in 26% of bi-allelic cases not solved previously by sequencing of coding regions. This strategy serves as a model study that can be applied to other inherited diseases in which only one or a few genes are involved in the majority of cases.

We observed bilateral cataracts on second trimester ultrasound, in two consecutive pregnancies, with no other structural defects detected. The parents were unrelated and had no family history for the disease. The first pregnancy was terminated in week 22. Copy number variation analysis revealed, in both the aborted fetus and the mother, a 495 kb duplication at 22q11.23 encompassing CRYBB3 and CRYBB2, and not present in variation databases. In the second pregnancy, lens hyperechogenicity was detected by ultrasound at week 13 and 4 days. The identical duplication at 22q11.23 was found in the fetus and considered as possibly pathogenic. At weeks 22 and 30, smaller orbit measurements were elucidated on ultrasound, raising concerns as to the underlying molecular genetic cause, necessitating further investigation. Whole-exome sequencing, using DNA of the first fetus, was performed shortly after the birth of a male child, and two truncating RAB3GAP1 mutations were detected: c.538G>T; p. (Glu180*) and c.943C>T; p. (Arg315*). Neither mutation has been previously reported to be disease-causing; however, evaluation in the context of previously published literature indicated their deleterious nature, implying a clinical diagnosis of Warburg micro syndrome or Martsolf syndrome. Sanger sequencing confirmed segregation of the two mutations within the family, consistent with autosomal recessive inheritance. The child born from the second pregnancy showed features typical of Warburg micro syndrome, with the exception of microcephaly, at age 31 months. © 2016 Wiley Periodicals, Inc.

The aim of this study was to determine the molecular genetic basis of an early-onset severe retinal dystrophy in three unrelated consecutive patients of Czech origin and to describe their ocular phenotype. DNA samples from two probands were analyzed using a genotyping microarray (Asper) followed by either target analysis of 43 genes implicated in retinal disorders by next generation sequencing or whole-exome sequencing, respectively. The third proband underwent conventional Sanger sequencing of CRB1 based on her ocular findings. All three probands harboured a known disease-causing mutation c.2843G>A; p.(Cys948Tyr) in the CRB1 gene. One individual was homozygous for this mutation, while in the other two probands c.2308G>A; p.(Gly770Ser) and c.3121A>G; p.(Met1041Val) were also identified in the heterozygous state, respectively. Both variants were novel and evaluated by in silico analysis as pathogenic. A false-negative result was observed in one of the two samples examined by the genotyping microarray. Disease onset in all patients was before the age of 7 years. Hypermetropic refractive error, bilateral nummular retinal pigmentation, retinal thickening and cystoid spaces in the macula were observed in two probands, aged 6 and 7 years. The third proband, aged 28 years, had bone spicule-like pigmentary changes associated with increased retinal nerve fiber layer. The first study reporting on the molecular genetic cause of non-syndromic early-onset severe retinal dystrophy in Czech patients identified one homozygous and two compound heterozygote probands with CRB1 mutations. Retina nerve fibre layer measurements should be considered an integral part of the clinical evaluation of retinal dystrophies. Detailed clinical examination and imaging can both direct molecular screening and help to confirm or refute disease causation of identified variants.

Background Hereditary hyperferritinemia-cataract syndrome (HHCS) is an autosomal dominant disorder manifesting with high serum ferritin levels and the formation of early-onset cataracts, with numerous small opacities, predominantly in the lens cortex. HHCS is caused by mutations in the iron-responsive element of the FTL gene. The aim of this study was to establish a molecular diagnosis in three Czech probands with suspected HHCS. Methods A complex ocular and systemic evaluation, including ferritin and iron measurements, was performed. The 5′ untranslated region of FTL was directly sequenced in all available family members, followed by paternity testing in one family. Results Three different FLT pathogenic variants (c.-161C>T, c.-167C>T, and c.-168G>C) present in the heterozygous state were detected in each of the 3 probands. Two segregated with the disease phenotype within the families, but c.-167C>T occurred de novo (confirmed by paternity testing). Prior to establishing molecular diagnosis, two probands were misdiagnosed with hemochromatosis. One individual, aged 43 years, underwent phlebotomy; another, aged 8.5 years, was treated with the iron chelator deferasirox, leading to life-threatening acute hyperammonemia, without severe liver injury. Conclusions Lack of family history does not exclude HHCS, because the pathogenic variant can arise de novo. Noncoding regions are often omitted from diagnostic gene panels, thus evading detection. Careful clinical evaluations and targeted genetic screening are important for avoiding potentially harmful treatments.

Leber hereditary optic neuropathy (LHON) and mitochondrial encephalopathy, myopathy, lactic acidosis and stroke-like episodes (MELAS) syndromes are mitochondrially inherited disorders characterized by acute visual failure and variable multiorgan system presentation, respectively.A 12-year-old girl with otherwise unremarkable medical history presented with abrupt, painless loss of vision. Over the next few months, she developed moderate sensorineural hearing loss, vertigo, migraines, anhedonia and thyroiditis. Ocular examination confirmed bilateral optic nerve atrophy. Metabolic workup documented elevated cerebrospinal fluid lactate. Initial genetic analyses excluded the three most common LHON mutations. Subsequently, Sanger sequencing of the entire mitochondrial DNA (mtDNA) genome was performed.Whole mtDNA sequencing revealed a pathogenic heteroplasmic mutation m.13046TC in MTND5 encoding the ND5 subunit of complex I. This particular variant has previously been described in a single case report of MELAS/Leigh syndrome (subacute necrotizing encephalopathy). Based on the constellation of clinical symptoms in our patient, we diagnose the condition as LHON/MELAS overlap syndrome.We describe a unique presentation of LHON/MELAS overlap syndrome resulting from a m.13046TC mutation in a 12-year-old girl. In patients with sudden vision loss in which three of the most prevalent LHON mitochondrial mutations have been ruled out, molecular genetic examination should be extended to other mtDNA-encoded subunits of MTND5 complex I. Furthermore, atypical clinical presentations must be considered, even in well-described phenotypes.

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.

Keratoconus is a bilateral disease characterized by progressive corneal thinning leading to irregular astigmatism that results in significant visual impairment. Despite extensive research, the exact etiopathogenesis of keratoconus remains unknown. Many copper-dependent enzymes such as superoxide dismutases, cytochrome c oxidase and lysyl oxidase have been shown to be altered in keratoconic corneas, and a decrease of copper levels in the diseased tissue has been reported as well. We propose a hypothesis linking all the putative pathways of keratoconus development and suggest that copper imbalance in corneal tissue may be an independent risk factor for the disease. The assessment of copper levels and its distribution in keratoconic corneas warrants further investigation.

Diamond nanoparticles (DNPs) of various types have been recently reported to possess antibacterial properties. Studies have shown a decrease of the colony forming ability on agar plates of the bacteria that had been previously co-incubated with DNPs in the suspension. Before plating, bacteria with DNPs were adequately diluted in order to obtain a suitable number of colony forming units. However, residual DNPs were still present on an agar plate, concentrated on the surface during the plating process; this introduces a potential artifact which might affect colony growth. The effect of DNPs remaining on the surface, alongside growing bacteria, has not been previously investigated. In this work, we present the experiments designed to investigate the effect of DNPs on bacterial survival and on the growth of the bacterial colony on a solid media. We employed Escherichia coli and Bacillus subtilis as models of Gram-negative and Gram-positive bacteria, respectively, and Proteus mirabilis as a model of bacterium exhibiting swarming motility on the surfaces. We analyzed the number, area, and weight of bacterial colonies grown on the agar surface covered with DNPs. We did not observe any bactericidal effect of such applied DNPs. However, in all bacterial species used in this work, we observed the appreciable reduction of colony area, which suggests that DNPs obstruct either bacterial growth or motility. The most obvious effect on colony growth was observed in the case of motile P. mirabilis. We show that DNPs act as the mechanical barrier blocking the lateral colony growth.

Purpose: Brittle cornea syndrome 1 (BCS1) is a rare recessive condition characterised by extreme thinning of the cornea and sclera, caused by mutations in ZNF469. Keratoconus is a relatively common disease characterised by progressive thinning and ectasia of the cornea. The aetiology of keratoconus is complex and not yet understood, but rare ZNF469 variants have recently been associated with disease. We investigated the phenotype of BCS1 carriers with known pathogenic ZNF469 mutations, and recruited families in which aggregation of keratoconus was observed to establish if rare variants in ZNF469 segregated with disease. Methods: Patients and family members were recruited and underwent comprehensive anterior segment examination including corneal topography. Blood samples were donated and genomic DNA was extracted. The coding sequence and splice sites of ZNF469 were PCR amplified and Sanger sequenced. Results: Four carriers of three BCS1-associated ZNF469 loss-of-function mutations (p.[ Glu1392Ter], p.[Gln1930Argfs*6], p.[Gln1930fs*133]) were examined and none had keratoconus. One carrier had partially penetrant features of BCS1, including joint hypermobility. ZNF469 sequencing in 11 keratoconus families identified 9 rare (MAF≤0.025) variants predicted to be potentially damaging. However, in each instance the rare variant(s) identified, including two previously reported as potentially keratoconus-associated, did not segregate with the disease. Conclusions: The presence of heterozygous loss-of-function alleles in the ZNF469 gene did not cause keratoconus in the individuals examined. None of the rare non-synonymous ZNF469 variants identified in the familial cohort conferred a high risk of keratoconus, therefore, genetic variants contributing to disease pathogenesis in these 11 families remain to be identified.

After cold shock, the Bacillus subtilis desaturase Des introduces double bonds into the fatty acids of existing membrane phospholipids. The synthesis of Des is regulated exclusively by the two-component system DesK/DesR; DesK serves as a sensor of the state of the membrane and triggers Des synthesis after a decrease in membrane fluidity. The aim of our work is to investigate the biophysical changes in the membrane that are able to affect the DesK signalling state. Using linear alcohols (ethanol, propanol, butanol, hexanol, octanol) and benzyl alcohol, we were able to suppress Des synthesis after a temperature downshift. The changes in the biophysical properties of the membrane caused by alcohol addition were followed using membrane fluorescent probes and differential scanning calorimetry. We found that the membrane fluidization induced by alcohols was reflected in an increased hydration at the lipid-water interface. This is associated with a decrease in DesK activity. The addition of alcohol mimics a temperature increase, which can be measured isothermically by fluorescence anisotropy. The effect of alcohols on the membrane periphery is in line with the concept of the mechanism by which two hydrophilic motifs located at opposite ends of the transmembrane region of DesK, which work as a molecular caliper, sense temperature-dependent variations in membrane properties.

Purpose To identify the molecular genetic cause in four families of various ethnic backgrounds with cornea plana. Methods Detailed ophthalmological examination and direct sequencing of the KERA coding region in five patients of Czech and Turkish origin and their available family members. Results Compound heterozygosity for a novel missense mutation c.209C>T; p.(Pro70Leu) and a novel splice site mutation c.887-1G>A in KERA were detected in two affected siblings of Czech origin. In silico analysis supported the pathogenicity of both variants. The second proband of Czech origin harboured c.835C>T; p.(Arg279*) in a homozygous state. Homozygous mutations c.740A>G; p.(Asn247Ser) and c.674C>T; p.(Ile225Thr) were identified in the Turkish probands, both born out of consanguineous marriages. Observed ocular phenotypes were typical of cornea plana with the exception of one Czech patient who also had marked thinning and protrusion in the superior part of the left cornea (mean keratometry 47.2 D). No corneal endothelial cell pathology was found by specular microscopy in seven eyes, in three eyes visualization of the posterior corneal surface was unsuccessful. Conclusion KERA mutation c.740A>G has been identified to date in three different populations, which makes it the most frequently occurring mutation in patients with cornea plana. Marked corneal thinning and ectasia are a very rare finding in this disorder and longitudinal follow-up needs to be performed to determine its potential progressive nature.

Inadequate cross-linking between collagen lamellae is a characteristic feature of keratoconus corneas. The formation of covalent bonds between collagen and elastin fibrils, which maintain the biomechanical properties of the cornea, is mediated by the cuproenzyme lysyl oxidase and four lysyl oxidase-like enzymes. The aim of this study was to determine the distribution of lysyl oxidase and the total lysyl oxidase activity (lysyl oxidase and the four lysyl oxidase-like enzymes) in control and keratoconic corneas. Seven control and eight keratoconic corneas were used for the imunohistochemical detection of lysyl oxidase in corneal cryosections using two different antibodies. The total lysyl oxidase activity in the culture medium of corneal fibroblasts from six explanted keratoconic and four control corneas was measured using a fluorometric assay in the presence and absence of the lysyl oxidase inhibitor beta-aminopropionitrile and determined as the production of H(2)O(2) in nM per μg of total protein. In the control tissue, the most intense signal for lysyl oxidase was present in the corneal epithelium, in which perinuclear dots brightly projecting from more or less homogenous cytoplasmic staining may represent the lysyl oxidase propeptide. Less intense staining was present in keratocytes, the extracellular matrix and in the corneal endothelium. The epithelium of the limbus and the perilimbal conjunctiva showed intense to very intense staining. The distribution of lysyl oxidase was clearly decreased in at least five of the eight keratoconic specimens. The most marked signal reduction was observed in the stromal matrix and in keratocytes. Moreover, the signal in pathological specimens revealed a more irregular pattern, including the presence of intra- and extracellular clumps in the epithelium. Interestingly, endothelial cells showed no or very weak staining in areas just beneath negative stromal tissue. The mean activity of total lysyl oxidase in the keratoconic samples (2.60 ± 2.23 nM H(2)O(2)/μg of total protein) was more than 2.5-fold lower than in control tissue (6.83 ± 2.53 nM H(2)O(2)/μg of total protein), and the decrease was statistically significant (p = 0.0178). The location of lysyl oxidase in the healthy cornea, limbus and perilimbal conjunctiva was described. We hypothesize that the restricted lysyl oxidase distribution in keratoconic corneas, and particularly the decrease of total lysyl oxidase activity in cultured keratoconic fibroblasts, is one potential reason for the inadequate collagen cross-linking that is a hallmark of this disease.

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.

Aims: To evaluate mutations in the transforming-growth-factor-β-induced (TGFBI) gene in patients of Czech origin with autosomal dominant corneal dystrophies. Methods: The coding sequence of the TGFBI gene was analysed in 22 affected Czech individuals from 7 apparently unrelated families. Comparison of phenotype to genotype was performed. Results: A H626P mutation, previously only described in a family with a variant of lattice corneal dystrophy (LCD), was detected in one family with superficial geographic corneal opacities. Light microscopy of 2 samples obtained following either a prior superficial keratectomy or keratoplasty showed amyloid but no fuchsinophilic deposits. In a family with LCD type I, an R124C mutation was identified. The R124L mutation was shown to be causative of Reis-Bücklers corneal dystrophy in 2 families. A family with Thiel-Behnke corneal dystrophy exhibited an R555Q mutation. In 2 families with granular corneal dystrophy type I, the typical R555W change was identified. Conclusion: The phenotype of the family with the H626P mutation differed from the phenotype previously reported for this change.

Summary Next-generation sequencing (NGS) represents one of the most significant technological advances in the biological sciences of the past decade. NGS is now being introduced by many laboratories for routine diagnostic use. For genetically heterogeneous disorders approaches include custom-designed target enrichment permitting analysis of disease-associated gene panels and whole exome sequencing (WES). The sensitivity, speed and cost per sample makes WES a valuable tool and it is increasingly being used to identify the molecular genetic causes of inherited cataracts. The detection rate of disease-causing mutations is high and the results enhance clinical diagnosis and genetic counselling of the affected families.

Corneal ectasias, among which keratoconus (KC) is the single most common entity, are one of the most frequent reasons for corneal grafting in developed countries and a threatening complication of laser in situ keratomileusis. Genome-wide association studies have previously found lysyl oxidase (LOX) and hepatocyte growth factor (HGF) associated with susceptibility to KC development. The aim of our study was to validate the effects of seven single-nucleotide polymorphisms (SNPs) within LOX and HGF over KC. Unrelated Czech cases with KC of European descent (108 males and 57 females, 165 cases in total) and 193 population and gender-matched controls were genotyped using Kompetitive Allele Specific PCR assays. Fisher's exact tests were used to assess the strength of associations. Evidence for association was found for both of the tested loci. It was strongest for rs3735520:G>A near HGF (allelic test odds ratio (OR)=1.45; 95% confidence interval (CI), 1.06–1.98; P=0.018) with A allele being a risk factor and rs2956540:G>C (OR=0.69; 95% CI, 0.50–0.96; P=0.024) within LOX with C allele having a protective effect. This first independent association validation of rs2956540:G>C and rs3735520:G>A suggests that these SNPs may serve as genetic risk markers for KC in individuals of European descent.

Keratan sulphate (KS) proteoglycans (PGs) are key molecules in the corneal stroma for tissue organisation and transparency. Macular corneal dystrophy (MCD) is a rare, autosomal recessive disease characterised by disturbances in KS expression. MCD is caused by mutations in CHST6, a gene encoding the enzyme responsible for KS sulphation. Sulphated KS is absent in type I disease causing corneal opacity and loss of vision. Genetic studies have highlighted the mutational heterogeneity in MCD, but supportive immunohistochemical studies on corneal KS have previously been limited by the availability of antibodies mostly reactive only with highly sulphated KS epitopes. In this study, we employed four antibodies against specific KS sulphation patterns, including one against unsulphated KS, to investigate their reactivity in a case of MCD compared with normal cornea using high-resolution immunogold electron microscopy. Mutation analysis indicated type I MCD with deletion of the entire open reading frame of CHST6. Contrast enhanced fixation revealed larger PG structures in MCD than normal. Unlike normal cornea, MCD cornea showed positive labelling with antibody to unsulphated KSPG, but was negative with antibodies to sulphated KSPG. These antibodies will thus facilitate high-resolution investigations of phenotypic heterogeneity in support of genetic studies in this disease.

Mutations in the human transforming growth factor beta–induced gene (TGFBI) have been identified as disease-causing in several clinically distinct epithelial-stromal corneal dystrophies.1,2 Most co...

Purpose To describe the genotype-phenotype correlation and serial observations in a five-generation Czech family with retinitis pigmentosa (RP) associated with total blindness in females. Methods Comprehensive ophthalmological examination was performed in sixteen family members (nine females and seven males). Autosomal dominant inheritance was suspected and screening for known mutations by genotyping microarray was performed. Next, direct sequencing of ORF15 RPGR exon was undertaken. Results The c.2543delA, in ORF15 of the RPGR gene was detected. Three females became bilaterally totally blind in the sixth decade. Four examined females and five males showed pigmentary deposits, progressive visual field constriction, moderate to high myopia and myopic astigmatism. Three other females had moderate to high myopia and myopic astigmatism but without the presence of bone spicule formation. Only one 34 year old female carrier had clinically normal fundus findings. Conclusion The c.2543delA in RPGR is associated with severe phenotype in females in the studied family. The presence of refractive errors, especially high myopia and astigmatism in the absence of male to male transmission may be indicative of an X-linked inheritance.

Genetic determinants of keratoconus are still largely unknown. Over the last two decades there has been a shift from regarding keratoconus as a monogenic disease with variable expression towards a general consensus that it is most likely to be a multifactorial disorder with multiple genetic and environmental components​ contributing to its development. Twins are useful in assessing the heritability of traits. Discordant monozygotic twin pairs can be used to look for environmental and epigenetic factors. The contribution of twin studies to the understanding of keratoconus genetics will be discussed.

Aims: To characterise the role of the carbohydrate sulfotransferase gene ( CHST6 ) in macular corneal dystrophy (MCD) in Czech patients. Methods: The coding region of the CHST6 gene was directly sequenced in 10 affected and five unaffected members from eight apparently unrelated MCD families. The type of MCD was determined by enzyme-linked immunosorbent assay of antigenic keratan sulfate (KS) in serum and by immunohistochemical staining of corneas with monoclonal anti-KS antibody. Results: The following changes in the coding sequence of the CHST6 gene were observed; homozygous mutation of c.1A>T (p.M1?); homozygous mutation c.599T>G (p.L200R); compound heterozygosity for c.599T>G and c.614G>A (p.R205Q); compound heterozygosity for c.494G>A (p.C165Y) and c.599T>G; heterozygous c.599T>G mutation and no other change in the coding sequence. One proband exhibited no changes. The pathogenic mutation c.599T>G (p.L200R) was in allelic association with the c.484C>G (p.R162G) polymorphism. Nine patients from seven families were of MCD type I including the subtype IA. Conclusion: Four different CHST6 missense mutations, of which p.C165Y is novel, were identified. Allelic association of the c.[484C>G; 599T>G] in six probands out of eight, as well as occurrence of this particular allele in a heterozygous state in one healthy control individual, supports a common founder effect for MCD in the Czech Republic.

Purpose To determine the molecular genetic cause of posterior polymorphous corneal dystrophy (PPCD) in four Czech probands. Methods Extensive ophthalmological examination including Pentacam and specular microscopy, and direct sequencing of the ZEB1 coding region were performed. Results Two novel frameshift mutations within ZEB1 were identified; c.2617dup in exon 8 in a 21-year-old female, considered to be most likely de novo in origin, and c.698dup in exon 6 in a 21-year-old male. The first case had mild changes consistent with a PPCD diagnosis and best corrected visual acuity (BCVA) bilaterally was 1.0. The corneal phenotype of the second case was more severe with a BCVA of 0.4 in the right and 0.05 in the left eye. Corneas of both probands were abnormally steep (keratometry readings K1 ≥ 47.4 D and K2 45 ≥ 49.2 D) with increased pachymetry values, but no pattern indicative of keratoconus. Specular microscopy in both patients revealed reduced endothelial cell density (range 1055- 655 per mm2). Both probands had a history of surgery for inguinal hernia; the male patient also reported the presence of hydrocele. Conclusion Nucleotide changes within the coding region of ZEB1 underlie the pathogenesis of PPCD in 4 out of 23 (17.4%) Czech probands.

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.

To describe the ocular features of 6 Czech and British patients with posterior polymorphous corneal dystrophy (PPCD) caused by mutations in the zinc finger E-box binding homeobox 1 gene (ZEB1).Case note review of 4 individuals with p.E776fs mutation, one with p.Y719X and one with p.F375fs mutation within the ZEB1 gene.Five individuals exhibited endothelial and Descemet membrane changes consistent with the diagnosis of PPCD. We concluded that one 70-year-old female who had a normal endothelium at both slit lamp and non-contact specular microscopy was a case of non-penetrance. The onset of disease was as early as 3 months after birth. One patient had irregular astigmatism with inferior corneal steepening on videokeratography, but without corneal thinning or other signs of keratoconus. Two others had corneal steepening49D but with regular astigmatism. Three individuals underwent penetrating keratoplasty (PK) in 1 eye, with one patient treated for secondary glaucoma prior to the PK.The phenotype associated with changes in the ZEB1 gene exhibits variable expression and incomplete penetrance and seems to have a low risk for secondary glaucoma or the need for keratoplasty compared to PPCD linked to 20p11.2. There is insufficient data for phenotype correlations with PPCD caused by other genes.

Purpose To establish the origin of cells causing the recurrence of posterior polymorphous corneal dystrophy (PPCD). Methods A corneal explant obtained from a male patient suffering from PPCD, who had undergone repeat penetrating keratoplasty (female donor), was examined. Cytokeratin (CK) 19 was detected using indirect immunofluorescence to confirm the presence of abnormal epithelial-like cells on the endothelial layer. The origin of these CK19-positive aberrant cells was then determined using fluorescence in situ hybridization of the X and Y chromosomes. Results Two out of 559 cells evaluated (0.4%) were XX positive and CK19-negative throughout the pathological explant. 99.6% of the endothelial cells were positive for CK19 and exhibited XY staining. These results indicate that the abnormal endothelial cells, which overgrew the posterior surface of the explant within 3.5 years, originated from the patient (XY) but not from the donor tissue (XX). Extreme aggressivity of the cells could be clinically correlated with the finding of retrocorneal membrane on the iris, anterior synechiae, corectopia and secondary glaucoma. Conclusion PPCD recurrence is caused by the abnormal proliferation and migration of the patient’s aberrant endothelium, which remained localized at the periphery of the original cornea, into the donor graft. The presence of retrocorneal membrane prior to the surgery should be considered as an indication of potential aggressive behavior of these cells and it should be taken into consideration prior to the indication of corneal grafting.

Adenylate cyclase toxin-hemolysin (CyaA, ACT or AC-Hly) of the whooping cough agent Bordetella pertussis penetrates phagocytes expressing the integrin complement receptor 3 (CR3, CD11b/CD18, α(M)β(2) or Mac-1). CyaA translocates its adenylate cyclase (AC) enzyme domain into cell cytosol and catalyzes unregulated conversion of ATP to cAMP, thereby subverting cellular signaling. In parallel, CyaA forms small cation-selective membrane pores that permeabilize cells for potassium efflux, contributing to cytotoxicity of CyaA and eventually provoking colloid-osmotic cell lysis. To investigate whether the single-pass α-helical transmembrane segments of CR3 subunits CD11b and CD18 do directly participate in AC domain translocation and/or pore formation by the toxin, we expressed in CHO cells variants of CR3 that contained artificial transmembrane segments, or lacked the transmembrane segment(s) at all. The results demonstrate that the transmembrane segments of CR3 are not directly involved in the cytotoxic activities of CyaA but serve for maintaining CR3 in a conformation that is required for efficient toxin binding and action.

Purpose: To determine the changes in the expression and localization of the α1 - α6 collagen IV chains in Czech patients with posterior polymorphous corneal dystrophy (PPCD). Methods: 12 corneal buttons from 10 PPCD patients, as well as 8 corneal buttons obtained from healthy donors, were used. The tissues were snap-frozen in liquid nitrogen and stored at –70°C until processed. Indirect enzymatic immunohistochemistry was performed using antibodies against the α1 - α6 collagen IV chains. The intensity of the signal was graded under a light microscope using a scale: - negative, + mild, ++ moderate, and +++ intense positivity. The localization of the signal was examined in all corneal layers, especially in the basal membrane (BM), stroma and Descemet’s membrane (DM). Results: Staining for the α1 and α2 collagen IV chains was increased in DM of PPCD corneas and was shifted from the stromal side (in control tissue) to the endothelial side (in PPCD patients) of DM. We detected a more intense staining of α1 and α2 chains in the posterior stroma of PPCD patients. We detected α1 and α2 collagen IV chains in BM of cornea of PPCD patients. Staining for the α3 - α6 collagen IV chains did not differ significantly between control and PPCD specimens. Conclusions: The α collagen IV chains show great heterogeneity in their localization in distinct corneal layers. The α1 and α2 collagen IV chains accumulate in DM, the stroma and the BM of PPCD patients. The increased expression of the α1 and α2 collagen IV chains and the change in their localization can contribute to the increased endothelial proliferative capacity observed in PPCD patients.

Purpose To confirm and define a molecular basis for a case of mucolipidosis type IV (ML IV) with an extremely atypical phenotype pattern. Design Observational case report of a patient with ML IV with disease progression restricted to ocular symptoms. Methods Complete ophthalmologic and neurologic examination. Ultrastructural examination of white blood cells, skin, conjunctiva, and corneal epithelium. The MCOLN1 gene was sequenced from cDNA and the proportion of splicing variants were assessed by quantitative allele-specific polymerase chain reaction. Results Absence of any neurological abnormalities. Retinal pathologic features were the main cause of visual disability: low visual acuity and cloudy corneas since 2 years of age, progressive decrease in visual acuity since the age of 9 years. Ultrastructural examination showed storage lysosomes filled with either concentric membranes or lucent precipitate in corneal and conjunctive epithelia and in vascular endothelium. Cultured fibroblasts were free of any autofluorescence. Sequencing of the MCOLN1 gene identified compound heterozygosity for D362Y and A→T transition leading to the creation of a novel donor splicing site and a 4-bp deletion from exon 13 at the mRNA level. Both normal and pathologic splice forms were detected in skin fibroblasts and leukocytes, with the normal form being more abundant. Conclusions The case of this patient with ML IV is unique and is characterized by a curious lack of generalized symptoms. In this patient, the disorder was limited to the eyes and appeared without the usual psychomotor deterioration. The resulting phenotype is the mildest seen to date.

PURPOSE. Posterior polymorphous corneal dystrophy (PPCD) is an autosomal dominant disorder, affecting both the corneal endothelium and Descemet's membrane. In the Czech Republic, PPCD is one of the most prevalent corneal dystrophies. The purpose of this study was to determine the chromosomal locus of PPCD in two large Czech families, by using linkage analysis. METHODS. Linkage analysis was performed on 52 members of two Czech families with PPCD and polymorphic microsatellite markers and lod scores were calculated. The candidate gene VSX1 was also screened for mutations. RESULTS. Significant lod scores were obtained with microsatellite markers on chromosome 20. Linkage analysis delineated the Czech PPCD locus to a 2.7-cM locus on chromosome 20, region p11.2, between flanking markers D20S48 and D20S139, which excluded VSX1 as the disease-causing gene in both families. In addition, the exclusion of VSX1 was confirmed by sequence analysis. CONCLUSIONS. This study reports the localization of PPCD in patients of Czech origin to chromosome 20 at p11.2. Linkage data and sequence analysis exclude VSX1 as causative of PPCD in two Czech families. This refined locus for PPCD overlaps the congenital hereditary endothelial dystrophy (CHED1) disease interval, and it is possible that these corneal dystrophies are allelic.

Autosomal recessive congenital hereditary endothelial dystrophy (CHED2) is a severe and rare corneal disorder that presents at birth or shortly thereafter, characterized by corneal opacification and nystagmus. Recently the gene for CHED2 was identified and seven different mutations in the SLC4A11 gene were reported. Here, we report seven novel mutations and two previously identified mutations in families from India and the United Kingdom with recessive CHED. The novel changes include two nonsense (p.Trp240X; p.Gln800X) three missense (p.Glu143Lys; p.Cys386Arg; p.Arg755Trp) and two splice site mutations (c.2240+1G>A; c.2437-1G>A). Interestingly, the c.2398C>T (p.Gln800X) and c.2437-1G>A identified in two affected siblings represent the first compound heterozygous mutations in the SLC4A11 gene.

Objective To search for genetic factors that could increase susceptibility to keratoconus. Methods A single-nucleotide polymorphism chip method was used to generate whole-genome data in a multiethnic panel of 6 families with 3 to 5 members affected by keratoconus. Candidate gene screening was performed by direct sequencing. Results Linkage analysis results were strongest for a locus on chromosome 14q24.3. This region contains a relatively small number of genes of potential interest, including VSX2 , a homeobox gene known to be involved in eye development and implicated in a spectrum of ocular disorders. However, sequencing the coding region of VSX2 did not reveal a sequence variant segregating with disease in any of the families described. Conclusion To our knowledge, this is the first report of linkage for keratoconus to 14q24.3 and the region is likely to harbor important inheritable genetic factors that may affect susceptibility to keratoconus. Clinical Relevance Further genetic research is needed to identify the genes responsible for keratoconus. This knowledge will aid in understanding the molecular pathophysiology of this condition and may lead to improved treatment strategies.

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.