CTG18.1 repeat expansion may reduce TCF4 gene expression in corneal endothelial cells of German patients with Fuchs' dystrophy.

PURPOSE: It was the aim of this investigation to elucidate the functional effects of CTG18.1 trinucleotide repeat expansion and the polymorphism rs613872 in the transcription factor 4 (TCF4) in corneas of patients affected by Fuchs' endothelial corneal dystrophy (FECD). METHODS: Sixty-one unrelated German patients with FECD and 113 unaffected controls were investigated and genotyped for the CTG18.1 locus by triplet primed PCR (TP-PCR) and the rs613872 polymorphism via Sanger sequencing and by employing genomic DNA from peripheral blood leucocytes. DNA and RNA retrieved from human corneal endothelial explants were examined for alterations in the gene expression of TCF4, ZEB1, E-cadherin, N-cadherin, as well as the CTG18.1 locus. RESULTS: The CTG18.1 trinucleotide repeat expansion (>50 repeats) was detected in the peripheral blood in 77% of affected FECD patients and 11.5% of the healthy volunteers. Applying the TP-PCR method, the length of CTG18.1 repeat expansions correlates in the blood and corneal cells. We noted that the CTG18.1 trinucleotide repeat expansion was associated with reduced TCF4 and ZEB1 gene expression, especially in the explanted corneal endothelial cells. While E-cadherin gene expression was not detected in any corneal endothelial cells, expression of CDH2 (N-cadherin) was detected in FECD-affected endothelium and in our controls. CONCLUSIONS: The CTG18.1 repeat expansion may reduce gene expression of TCF4 and ZEB1, suggesting that a mechanism triggering a loss of function may contribute to FECD. The correlation of CTG18.1 repeat expansion from blood and the cornea may represent the first step toward investigating the potential relevance of testing the blood of cornea donors to minimize the risk of transplanting grafts potentially affected with FECD.

Identification of two novel mutations in the cornea-specific TGFBI gene causing unique phenotypes in patients with corneal dystrophies.

The purpose of this study was to report on two novel missense mutations of the cornea-specific TGFBI gene in one single patient and in two generations of a family diagnosed with unique corneal dystrophy (CD) phenotypes. Ophthalmologic examination, in several cases ocular coherence tomography of the anterior segment (AS-OCT), was performed in 21 affected patients and in two unaffected members of one affected family. Coding regions of the TGFBI gene were direct sequenced in all 23 individuals. The two novel mutations were verified by RFLP analysis. A novel mutation c.1640T > G (p.Phe574Cys) in exon 12 of the TGFBI gene was detected in one single patient with recurrent granular intrastromal deposits comparable to a type of granular dystrophy. In AS-OCT, the deposit pattern reached up to the Descemet's layer. A further novel mutation c.393G > T(p.Glu131Asp) in exon 4 of the TGFBI gene was detected in all three affected members of one family with superficial cloud- and honeycomb-like opacifications, comparable to a Schnyder corneal dystrophy. Two unaffected members did not carry this alteration. The two identified novel mutations add other two phenotypes in patients suffering from TGFBI-linked CD to those reported so far. In one case, clinical finding indicates a Schnyder corneal dystrophy-like phenotype due to its superficial crystalline shape, and in the second one, granular deposits who reach Descemet's layer indicate a granular CD subtype. Molecular genetic analysis may help to distinguish those subtypes and to decide for specific treatment in time of a wide variation of corneal surgical techniques.

A corneal dystrophy associated with transforming growth factor beta-induced Gly623Asp mutation an amyloidogenic phenotype.

PURPOSE: To present the light and electron microscopic findings of a unique corneal dystrophy never before described in a German family carrying the Gly623Asp Mutation of the TGFBI gene with late clinical onset. DESIGN: Experimental study. PARTICIPANTS: Four affected and 6 nonaffected family members. METHODS: Slit-lamp examination, photographic documentation, and isolation of genomic DNA from peripheral blood leucocytes obtained from each family member examined. Exons 3, 4, 5, and 11 to 14 of the TGFBI gene were amplified and sequenced in these family members. Five corneal buttons of 3 affected siblings were excised at the time of penetrating keratoplasty. Light and electron microscopic examination were performed including immunohistochemistry with antibodies against keratoepithelin (KE) 2 and 15. MAIN OUTCOME MEASURES: Clinical and histologic characteristics of corneal opacification in affected patients and presence of coding region changes in the TGFBI gene. RESULTS: The specimens showed destructive changes in Bowman's layer and the adjacent stroma. Patchy Congo red-positive amyloid deposits were found within the epithelium in 1 cornea, in Bowman's layer and in the anterior stroma of all specimens also showing KE2, but not KE15, immunostaining. Electron microscopy revealed deposits mainly located in the anterior stroma and Bowman's layer and in small amounts in the basal area of some epithelial cells. The destroyed areas were strongly Alcian blue-positive, the Masson Trichrome stain proved mainly negative for the deposits. All affected but none of the unaffected family members had a heterozygous missense mutation in exon 14 of the TGFBI gene (G-->A transition at nucleotide 1915) replacing glycin by aspartic acid amino acid (Gly623Asp) at position 623 of the KE protein. CONCLUSIONS: In contrast with the patient carrying the Gly623Asp mutation of the TGFBI gene described by Afshari et al, our cases presented with Salzmann's nodular degeneration-like clinical features and their specimens contained KE2-positive amyloid. The reason for this now "meeting the expectation histologic phenotype" is unclear. The histologic findings emphasize that this is a unique corneal dystrophy, which shares no clinical characteristics with Reis-Bücklers' dystrophy and should be treated as a distinct entity. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any materials discussed in this article.

Surgical outcome after phototherapeutic keratectomy in patients with TGFBI-linked corneal dystrophies in relation to molecular genetic findings.

PURPOSE: To evaluate the correlation between surgical outcome after phototherapeutic keratectomy in patients with autosomal dominant transforming growth factor, beta-induced (TGFBI)-linked corneal dystrophies (CD) and molecular genetic findings regarding the TGFBI gene. METHODS: Twelve patients were examined to investigate genotype by direct sequencing of the TGFBI gene. Twenty eyes of 12 patients were treated with phototherapeutic keratektomy (PTK) to remove superficial corneal opacifications and to decrease recurrent erosions. Surgical outcome, including visual improvement, recurrence of opacifications, postoperative complications, and additional therapeutic proceedings were reported and compared with the molecular genetic results. RESULTS: Four different missense mutations were identified within the coding region of the TGFBI gene: Arg124Cys in one eye, Arg555Trp in nine eyes, Arg124His in four eyes and Gly623Arg in six eyes. In all eyes the PTK was successful without clinically significant recurrent opacifications after a mean follow-up time of 17.6 months (min 3 months, max 42 months). The best corrected visual acuity (BCVA) improved with an average increase of 3.1 lines (minimum 2 lines, maximum 5 lines). In one eye (Arg124Cys), we observed delayed wound healing and a delayed increase in BCVA, in two eyes we performed an Epilasik to correct remaining hyperopia, and in four eyes we fitted rigid gas-permeable tricurve contact lenses to correct the remaining irregular astigmatism. CONCLUSIONS: The variable genotypes in patients with TGFBI-linked corneal dystrophies lead to significantly different results after surgical treatment. The Gly623Arg mutation seems to be an optimum genotype on which to perform PTK even in older patients. It is essential to determine the genotype in order to standardize the PTK treatment and to evaluate the success in TGFBI-linked corneal dystrophies.

Macular corneal dystrophy: mutational spectrum in German patients, novel mutations and therapeutic options.

INTRODUCTION: The objective of this study was to investigate genotype-phenotype correlations, the consequences for surgical treatment, and the therapeutical options in patients with macular corneal dystrophy (MCD). MATERIAL AND METHODS: We investigated MCD genotype by using polymerase chain reaction followed by direct sequencing in one family and four patients with MCD. Results were confirmed by restriction analysis. Clinical phenotypes, histopathological findings, and therapeutical proceedings of each patient were reported and compared with the molecular genetic results. RESULTS: Five mutations, four missense mutations, and one frameshift mutation, from which three were novel, and one single-nucleotide polymorphism, were identified within the coding region of the CHST6 gene. In three patients, two with a homozygous mutation within the start codon (Met1Leu) and one with a heterozygous mutation (Leu200Arg) and a polymorphism (Arg162Gly), with irregular corneal surface and recurrent erosions a phototherapeutic keratectomy lead to a transient success. An additional fitting of rigid gas permeable contact lenses in one patient could further improve irregular astigmatism. In two patients, one with a frameshift mutation (1734_1735delTG; Arg211Gln) and one with two compound heterozygous mutations (Leu200Arg; Leu173Phe) and an additional polymorphism (Arg162Gly) a penetrating keratoplasty improved BCVA without any recurrence of the opacities within the follow-up time. DISCUSSION: Different genotypes imply several phenotypes, which influence therapeutical proceedings in MCD patients. Our study shows the wide range of diagnostic findings and therapeutical options in patients suffering from macular corneal dystrophy depending on the genotype.

Varieties of contact lens fittings after complicated hyperopic and myopic laser in situ keratomileusis.

PURPOSE: To determine whether contact lenses with a special back surface design can improve visual acuity after complicated laser in situ keratomileusis (LASIK). METHODS: Fifteen eyes (six after myopic LASIK and nine after hyperopic LASIK) of eight patients were fitted with contact lenses with a special back surface design for optical rehabilitation. Four different types of lenses (aspheric, tricurve, keratoconus, and reverse) were used selectively, depending on the abnormal eccentricity (positive and exceeding 0.5-0.7 in all preoperatively hyperopic eyes, negative in all preoperatively myopic eyes) determined by videokeratoscope and on individual conditions. The patients were followed up retrospectively for an average period of 12.3 months. Lens tolerance and corrected visual acuity were evaluated and compared with the results obtained with spectacles. RESULTS: Visual acuity improved in nine (60%) of 15 eyes (three eyes by more than three lines and six eyes by three lines or fewer), with an absence of halos and ghost images in four (26.7%) of 15 eyes accompanied by good contact lens tolerance and a satisfactory contact lens fit. There were no noticeable complications. CONCLUSIONS: Contact lens fitting after LASIK is a safe and reliable procedure for improving visual acuity and reducing complications, such as ghost images or irregular corneal surface. Depending on the eccentricity and therefore on the preoperative refraction, contact lenses with a special back surface design can minimize problems in contact lens fitting and can improve tolerance and visual results.

Refractive error after triple and non-simultaneous procedures: is the application of a standard constant keratometry value in IOL power calculation advisable?

PURPOSE: The purpose of this investigation was to determine whether or not the use of a standard constant keratometry value in cases of preoperative abnormal keratometry values in biometry for triple procedures is advisable. METHODS: Cataract surgery and penetrating keratoplasty were performed in 82 eyes; 53 eyes underwent triple procedures and 29 eyes underwent non-simultaneous procedures. A standard constant keratometry value of 42.50 D was applied in 18 triple-procedure eyes because the preoperative measured keratometry values were outwith the normal range (41-47 D). The spherical equivalent and expected values were compared after a mean follow-up of 20.5 months. RESULTS: Cases in the triple-procedure group that achieved spherical equivalent within +/- 2.0 D of expected values included nine of 18 eyes (50%) in which a standard constant keratometry value of 42.50 D was applied, three of 17 eyes (18%) in which keratometry values outwith the normal range were applied (p = 0.044), and eight of 18 eyes (45%) in which keratometry values within the normal range were applied (p = 0.862). Cases in the non-simultaneous procedure group that achieved spherical equivalent within +/- 2.0 D of expected values included 22 of 24 eyes (92%) in which keratometry values within the normal range were applied (p = 0.0025), and five of five eyes (100%) in which a standard constant keratometry value was applied. CONCLUSIONS: The application of a standard constant keratometry value of 42.50 D for intraocular lens power calculation in triple procedures can be recommended if abnormal keratometry values were measured previously. If possible, non-simultaneous procedures should take priority.

Molecular genetic and ocular findings in patients with holt-oram syndrome.

PURPOSE: The autosomal dominant Holt-Oram syndrome (HOS) is characterized by upper limb and cardiac septal defects. Mutations of the TBX5 gene have been identified as the underlying gene defect in HOS. Embryonic expression of TBX5 has been found in the human retina. This is the first report of ocular findings in two unrelated families with mutations in the TBX5 gene. METHODS: Six living persons affected with HOS and 10 unaffected family members were subjected to mutation analysis and complete ophthalmological examination, including electrophysiological examinations (EOG and flash ERG). RESULTS: A heterozygous single base-pain substitution in exon 5 (408C --> A) was detected in all affected patients. All examined affected patents were ophthalmological asymptomatic with normal EOG. A scotopic elongated b-wave latency was found in affected family members who were older than 35 years. The ERG was normal in the young patients. CONCLUSIONS: Haploinsufficiency of TBX5 alters the dorsal-ventral polarity in developing eye vesicles without amy detected functional loss in human. Slight ERG abnormalities later in life may be a result of changes induced by the inner ganglion cell layer in the inner nuclear layer.

Holt-Oram syndrome: a new mutation in the TBX5 gene in two unrelated families.

Holt-Oram syndrome (HOS) is a specific developmental defect involving upper limb malformations and cardiac defects. Mutations in the TBX5 gene, located on chromosome 12q24.1, were demonstrated as the underlying molecular defect in several families with this disorder. We report on two unrelated families with HOS. Affected members of both families have the same truncation mutation in exon 5 of the TBX5 gene (Y136X). This mutation has not been reported before in HOS. The spectrum of defects is similar in both families, displaying an ASD, hypoplastic deltoid muscles and hypoplastic or absent thumbs extending to radial defects in one case. So far, only a single genotype-phenotype analysis in HOS has been done which is not sufficient to explain the high inter- and intrafamilial variability of expression. Our observation further supports that the position of the mutation in the TBX5 gene is related to the phenotype expression of HOS.