Reis-Bücklers Corneal Dystrophy Research Articles

Recurrence Characteristics on Optical Coherence Tomography and Treatments of Reis-Bücklers Corneal Dystrophy After Phototherapeutic Keratectomy or Penetrating Keratoplasty

PurposeTo evaluate the recurrence characteristics on optical coherence tomography and clinical outcomes after phototherapeutic keratectomy (PTK) or penetrating keratoplasty (PKP) in patients with Reis-Bücklers corneal dystrophy (RBCD). DesignRetrospective interventional case series. MethodsSeventeen patients with RBCD (31 eyes, including six surgery-naïve eyes and 25 surgical eyes) received 44 surgical interventions from 1996 through 2022. PTK or PKP was performed as the initial surgical procedure. Significant recurrence was determined when best spectacle-corrected visual acuity decreased at least two lines with increased opacity in the superficial cornea. Repeated PTK or PTK on the corneal graft (CG-PTK) was considered if patients could not endure poor vision due to significant recurrence. Recurrence depth and annual increase in thickness of the central cornea and subepithelial deposits were assessed by anterior segment optical coherence tomography. ResultsThe mean follow-up time was 12.8±8.5 years (range, 2.0–25.5 years). The mean logMAR best spectacle-corrected visual acuity improved from 1.24±0.48 preoperatively to 0.27±0.09 postoperatively in the initial PTK group (13 eyes, P<0.001), from 1.84±0.69 to 0.40±0.13 in the PKP group (12 eyes, P<0.001), from 1.04±0.46 to 0.30±0.07 in the repeated PTK group (12 times in 7 eyes, P<0.001), and from 1.29±0.43 to 0.39±0.11 in the CG-PTK group (7 times in 5 eyes, P=0.001). The median significant recurrence time was 27 months (95% confidence interval 23.9-30.1), 96 months (84.1-107.9), 31 months (28.8-33.1), and 24 months (19.8-28.2), respectively (P<0.001). The depth of superficial deposits located between the epithelium and the anterior stroma was approximately 115μm (85-159μm). The annual thickening of subepithelial deposits was 14±2μm after initial PTK, 7±3μm after PKP, 14±3μm after repeated PTK, and 30±11μm after CG-PTK, compared to 4±2μm in surgery-naïve eyes (P=0.002, 0.515, 0.002, <0.001). The thickness of the central cornea increased by 15±2μm, 7±2μm, 15±3μm, and 31±10μm per year in the four surgery groups, respectively, compared to 5±2μm in surgery-naïve eyes (P=0.001, 0.469, 0.001, <0.001). ConclusionsBetter visual acuity can be achieved after PTK than PKP for treatment of RBCD. The annual thickening of subepithelial deposits may approximate an increase in central corneal thickness. The superficial distribution of subepithelial deposits makes it feasible to perform repeated PTK, even on the corneal allograft, for recurrent RBCD.

Clinical and Optical Coherence Tomography Correlation of Recurrence Patterns After Femtosecond Laser-Assisted Anterior Lamellar Keratoplasty in Reis-Bucklers Corneal Dystrophy.

The aim of this study was to report the clinical profile and patterns of recurrence after femtosecond laser-assisted anterior lamellar keratoplasty (FALK) in Reis-Bucklers corneal dystrophy. This is a case series of 5 eyes of 4 patients with Reis-Bucklers corneal dystrophy. Clinical images of recurrence were correlated with the high-resolution optical coherence tomography. Histopathologic examination of excised corneal samples was performed when possible. The median time to recurrence was 2 (1-5) years after FALK. Of the 5 eyes, 1 eye had primary FALK, whereas 4 eyes had secondary interventions, which included previous phototherapeutic keratectomy (once in 1 eye and twice in 2 eyes), and previous penetrating keratoplasty, followed by phototherapeutic keratectomy (1 eye). Recurrence was noted at the level of the subepithelium. In addition, 1 eye showed interface deposits along with epithelial downgrowth at the graft-host bed. The 2 distinct patterns of recurrence noted were at the subepithelial region and the interface. The clinical patterns of recurrence favor an epithelial origin of recurrent deposits.

Recurrence in Reis Bücklers corneal dystrophy: Clinicopathological correlation

<br>We report a case series highlighting clinical correlation of recurrence of Reis–Bucklers corneal dystrophy (RBCD) with histopathology (HPE), genetic analysis, and electron microscopy (EM). This was an interventional case series of three cases in three generations of one family. The index case was a 23-year-old male with bilateral recurrent RBCD following OD PTK and OS ALTK done 6 years earlier. His father had undergone OU PK. His 35-year-old sister and 9-year-old niece were also affected who underwent OU ALTK. Clinical examination, histopathological examination (HPE), and electron microscopy (EM) evaluation were done. The recurrence of RBCD was noted in one of the three members of the same family. Corneal examination showed a dense reticulate pattern of epithelial-stromal involvement. On HPE, disrupted Bowman's membrane and underlying abnormal subepithelial collagen staining positive with PAS and Masson's trichrome were noted. On EM, degenerated stroma with dense collagen fibrils in aggregates, dispersed among regular collagen fibrils, were noted. All four members showed TGFß1 mutation (chromosome 5q31) with Arg124Leu mutation. A trend toward more advanced presentation with increasing age of cases was noted. The clinical and pathological correlation was performed. Clinical correlation with HPE, EM with genetic analysis of RBCD is interesting with presentation severity varying in different generations.<br>

In vivo Imaging of Reis-Bücklers and Thiel-Behnke Corneal Dystrophies Using Anterior Segment Optical Coherence Tomography.

PurposeTo investigate in vivo corneal changes of genetically confirmed Reis–Bücklers corneal dystrophy (RBCD) and Thiel–Behnke corneal dystrophy (TBCD) using anterior segment optical coherence tomography (AS-OCT).DesignA single-center, prospective, comparative case series.MethodsSeven patients from 3 pedigrees (3 males, 4 females) with RBCD [Arg124Leu (R124L) heterozygous missense mutation of human transforming growth factor beta-induced (TGFBI) gene] and 4 patients from 3 pedigrees (3 males, 1 female) with TBCD [Arg555Gln (R555Q) heterozygous missense mutation of TGFBI gene] were examined. Six patients with RBCD and three patients with TBCD exhibited recurrence after corneal surgery including penetrating keratoplasty, phototherapeutic keratectomy, and electrolysis. All patients were examined by slit-lamp biomicroscopy followed by AS-OCT. Selected AS-OCT images of the cornea were evaluated qualitatively for changes in shape and degree of light reflection of corneal deposits.ResultsSlit-lamp biomicroscopy showed characteristic irregular gray opacities in Bowman’s layer in each dystrophy: a geographic pattern in RBCD and a honeycomb pattern in TBCD. In each dystrophy, distinct characteristic deposits were observed by AS-OCT as a banding lesion in Bowman’s layer and its adjacent epithelium/stroma. In RBCD, the banding lesion was highly reflective and sharply margined at the stroma. In contrast, deposits in TBCD in the same layer showed a saw-tooth pattern toward the epithelium and poorly margined at the stroma.ConclusionAS-OCT is able to clearly identify characteristic in vivo corneal microstructural changes associated with RBCD and TBCD. As a result, in vivo differentiation of RBCD and TBCD can be achieved.

Analysis of TGFBI Gene Mutations in Three Chinese Families with Corneal Dystrophy.

Objective To identify the types of TGFBI (transforming growth factor, beta-induced) gene mutations in three Chinese families with Reis–Bücklers corneal dystrophy (RBCD), lattice corneal dystrophy type I (LCDI), or Avellino corneal dystrophy (ACD) and to investigate the relationship between the phenotypes and genotypes of corneal dystrophy. Methods Peripheral blood was collected from 24 patients and 76 phenotypically normal members in three Chinese families as well as from 100 healthy controls. Genomic DNA was extracted. All 17 exons of the TGFBI gene, and the exon-intron junctions were examined by polymerase chain reaction (PCR) and direct DNA sequencing to identify and analyse gene mutations. In addition, all members of the three families were subjected to detailed clinical examinations. Results The heterozygous c.371G > T (p.R124L) mutation was detected in exon 4 of the TGFBI gene in nine patients from the family with RBCD. In contrast, this mutation was not found in the phenotypically normal members of the family. The heterozygous c.370C > T (p.R124C) mutation was found in exon 4 of the TGFBI gene in 11 patients from the family with LCDI. This mutation was not found in the phenotypically normal members of the family. The heterozygous c.371G > A (p.R124H) mutation was detected in exon 4 of the TGFBI gene in four patients from the family with ACD. Again, this mutation was not found in the phenotypically normal members of the family. The TGFBI gene mutations cosegregated with the disease phenotypes in the three families and exhibited an autosomal dominant mode of inheritance. No TGFBI gene mutations were detected in the 100 healthy controls. Conclusion There is a high degree of correlation between the phenotypes and genotypes of TGFBI-linked corneal dystrophies. R124 represents a mutational hotspot in the TGFBI gene. Gene mutation analysis provides a reliable basis for the definitive diagnosis of corneal dystrophy.

Analysis of TGFBI gene mutation in a Chinese family affected with Reis-Bucklers corneal dystrophy

To analyze the clinical features and TGFBI gene mutation in a Chinese family affected with Reis-Bucklers corneal dystrophy. Genomic DNA was extracted from 53 members including 9 patients from the family. The 17 exons and splice region of introns of the TGFBI gene were amplified by PCR and directly sequenced. All family members were subjected to ophthalmologic examination. A heterozygous mutation (R124L) was found in exon 4 of the TGFBI gene among all patients from the family. The same mutation was not found among unaffected family members. The inheritance pattern of the family was identified as autosomal dominant, and the Reis-Bucklers corneal dystrophy in the family was diagnosed as the geographic type. The R124L mutation of the TGFBI gene probably underlies the pathogenesis of Reis-Bucklers corneal dystrophy in this Chinese family. Molecular genetic approach is useful for the proper diagnosis of this type of corneal dystrophy.

New histopathologic and ultrastructural findings in Reis-Bücklers corneal dystrophy caused by the Arg124Leu mutation of TGFBI gene.

BackgroundReis-Bücklers corneal dystrophy (RBCD) was consistently reported as a corneal dystrophy only affected Bowman’s layer and superficial corneal stroma, and superficial keratectomy was a recommendation surgery for treatment in literatures. The study reported new histopathological and ultrastructural findings in RBCD caused by the Arg124Leu mutation of transforming growth factor induced (TGFBI) gene in a four-generation Chinese pedigree.MethodsSubjects including eight patients and seven unaffected family members received slit-lamp biomicroscopy and photography. DNA was obtained from all subjects, and exons 4 and 11 to 14 of TGFBI gene were analyzed by polymerase chain reaction and the products were sequenced. Anterior segment optical coherence tomography (AS OCT) and in vivo confocal microscopy were conducted for ten eyes of five patients. Based on the results of AS OCT and in vivo confocal microscopy, deep anterior lamellar keratoplasty (DLKP) using cryopreserved donor cornea was applied for four eyes of four patients. Four lamellar dystrophic corneal buttons were studied by light and transmission electron microscopy, and TGFBI immunohistochemistry.ResultsEight patients had typical clinical manifestations of RBCD presenting recurrent painful corneal erosion starting in their early first decades, along with age-dependent progressive geographic corneal opacities. TGFBI sequencing revealed a heterozygous mutation, Arg124Leu in all eight patients. Anterior segment optical coherence tomography and in vivo confocal microscopy showed the dystrophic deposits involved not only in subepithelial and superficial stroma, but also in mid- or posterior stroma in four examined advanced eyes. Light microscopy showed Bowman’s layer was absent, replaced by abnormal deposits stain bright red with Masson’s trichrome. In superficial cornea, the deposits stacked and produced three to five continuous bands parallel to the corneal collagen lamellae. In mid- to posterior stroma, numerous granular or dot- like aggregates were heavily scattered, and most of them presented around the nuclei of stromal keratocytes. Transmission electron microscopy revealed the multiple electron-dense rod-shaped deposits aggregated and formed a characteristic pattern of three to five continuous bands in superficial cornea, which were similar to those seen under light microscopy. In mid- to posterior stroma, clusters of rod-shaped bodies were scattered extracellular or intracellular of the stromal keratocytes between the stromal lamellae suggesting the close relationship between mutated proteins and keratocyte.ConclusionsThe study offer evidences indicating DLKP is a viable treatment option for advanced RBCD to avoid recurrence, and the mutated TGFBIp in dystrophic corneas are of keratocytes origin.

TGFBI Gene Mutation Analysis in Chinese Families with Corneal Dystrophies.

To identify transforming growth factor beta-induced (TGFBI) gene mutations in four Chinese families affected by corneal dystrophies. In this study, three families (21 patients and 18 normal relatives), respectively, with Reis-Bücklers corneal dystrophy (RBCD), classic lattice corneal dystrophy (LCDI), and variant LCD (LCDI/IIIA) were assessed. All subjects underwent a complete ophthalmological evaluation, including biomicroscopic inspection and dilated fundus examination. As a control, 100 individuals without corneal disease were selected from the general population. Polymerase chain reaction (PCR) and direct sequencing were used to screen for mutations in TGFBI. For the three families, a single heterozygous c.371G>T (R124L) point mutation was found in exon 4 of TGFBI in 14 affected members with RBCD, a single heterozygous c.370C>T (R124C) point mutation was found in exon 4 of TGFBI in four affected members with LCDI, and a single heterozygous c.1877A>G (H626R) point mutation was found in exon 14 of TGFBI in four affected members with LCDI/IIIA. TGFBI gene mutation had not been detected in the unaffected members and 100 normal controls. TGFBI gene mutations were present in all three Chinese families with corneal dystrophy, and our study further verified the relationship between phenotype and genotype of corneal dystrophy.

Analyses of TGFBI gene mutation spectrum in four Chinese families with corneal dystrophy

To identify the genetic mutation of TGFBI gene in four Chinese families with corneal dystrophy. The pedigrees were Reis-Bücklers corneal dystrophy (RBCD), Avellino corneal dystrophy (ACD), lattice corneal dystrophy type I(LCDI) and lattice corneal dystrophy type I/IIIA (LCDI/IIIA) (n = 1 each). Genomic DNA was extracted from leukocytes from 22 patients, 22 phenotypic normal family members and 100 normal controls from February 2010 to October 2012. And 17 exons of TGFBI gene were amplified by polymerase chain reaction and sequenced directly. The corneas were examined with slit-lamp biomicroscope and photographed. Mutations of TGFBI gene occurred in all 22 patients, including R124L (c.371G > T) in 14 patients with RBCD, R124H (c.371G > A) mutation in 1 patient with ACD, R124C (c.370C > T) mutation in 3 patients with LCDIand H626R (c.1877A > G) mutation in 4 patients with LCD I/IIIA. The mutations were absent in all participating unaffected family members and normal controls. TGFBI gene-linked corneal dystrophy has close genotype-phenotype relationship. And R124 is a mutant hotspot of TGFBI gene of corneal dystrophy.

Microkeratome-assisted two-stage technique of superficial anterior lamellar keratoplasty for Reis-Bücklers corneal dystrophy.

The aim of this study was to describe a microkeratome-assisted 2-stage technique of superficial anterior lamellar keratoplasty (SALK) to manage Reis-Bucklers corneal dystrophy (RBCD). A microkeratome was used to create a 9-mm, 140-μm-thick corneal flap in the first stage. Four weeks later, in the second stage, a Hessberg-Baron suction trephine was used to perform a 7.0-mm central trephination up to a depth of 150 μm, within the corneal flap. Donor lamellar tissue was prepared using a microkeratome system, after which a vacuum punch was used to trephine a 7.0-mm lamellar button. This donor button was used to replace the central corneal flap in the recipient cornea without using any sutures. A bandage contact lens was applied for 2 weeks. This modified technique of staged sutureless SALK was used in 4 eyes of 2 patients with RBCD. Postoperatively, all eyes experienced an improvement in both uncorrected and best spectacle-corrected visual acuities. The average best spectacle-corrected visual acuity was 20/30 at the last follow-up (19 months, range 16-22 months). The cornea remained clear in all eyes until the last follow-up without any evidence of recurrence of RBCD. The staged technique of microkeratome-assisted SALK allows the replacement of superficial corneal stroma without the necessity for any sutures and seems to be a safe and effective method for the treatment of RBCD.

Reis-Bücklers Corneal Dystrophy: A Reappraisal Using in vivo and ex vivo Imaging Techniques

Purpose: To characterize the phenotype of Reis-Bücklers corneal dystrophy (RBCD) using in vivo and ex vivo imaging techniques. Methods: Five RBCD patients with penetrating keratoplasty (PK) were enrolled. Before surgery, all patients underwent a complete ophthalmological examination including slitlamp biomicroscopy, in vivo confocal microscopy (IVCM) and anterior segment (AS) optical coherence tomography (OCT). After PK, corneal buttons were examined by light and transmission electron microscopy (TEM). Correlations between in vivo and ex vivo images were analyzed. Results: In all cases, irregular geographic-like subepithelial gray-white opacities were observed in the central and mid-peripheral cornea. AS-OCT images of the cornea of all patients revealed hyperreflective homogeneous and continuous deposits concentrated at the level of Bowman's layer and anterior stroma. Using IVCM, a highly reflective irregular amorphous material was observed from intermediate epithelial cells to the anterior stroma. Sparse deposits of highly reflective material were also detected in the posterior stroma. TEM showed in all specimens basal epithelial cells containing small vesicles with rod-shaped dense material. Conclusions: IVCM and AS-OCT may be a useful adjunct to biomicroscopy for the diagnosis and management of RBCD. The correlations between the different in vivo and ex vivo imaging techniques emphasize the hypothesis of an epithelial origin for RBCD.

Arg555Gln Mutation of TGFBI Gene in Geographical-Type Reis—Bücklers Corneal Dystrophy in a Chinese Family

Mutations of the transforming growth factor β-induced (TGFBI) gene were studied in a Chinese family with Reis-Bücklers corneal dystrophy (RBCD). Six family members with RBCD and six unaffected family members were investigated. The pedigree showed a typical dominant inheritance pattern. Genomic DNA was extracted from peripheral leucocytes from all study participants. Exons 4, 12 and 14 of the TGFBI gene were analysed using polymerase chain reaction, and standard automated sequencing was performed. Corneal tissue sampled from the proband during phototherapeutic keratectomy was examined using transmission electron microscopy (TEM). A typical geographical pattern of fine opacities in Bowman's layer of the cornea was seen in all six patients on slit-lamp examination. An Arg555Gln (R555Q) mutation of the TGFBI gene was identified in all six patients but was absent in all unaffected family members. TEM revealed rod-shaped bodies in Bowman's layer of the cornea. In this Chinese family an R555Q mutation of the TGFBI gene was associated with RBCD. As the RBCD phenotype is usually associated with an R124L mutation, this novel genotype-phenotype correlation may prompt further investigation of Bowman's layer corneal dystrophy.

TGFBI gene mutation in a Chinese pedigree with Reis‐Bücklers corneal dystrophy

To characterize the molecular defects in the TGFBI gene in a Chinese family with Reis-Bücklers corneal dystrophy (RBCD), and to study the relationship between the gene mutations and the clinical manifestations. Four generations of this family with RBCD were enrolled in the study. In addition to ophthalmic and histopathological examinations, polymerase chain reaction (PCR) amplification and analysis of nucleotide sequencing of exons 4, 12, 14 of TGFBI were performed. The clinical manifestations of the disease were characterized by geographic opacities in the subepithelial layers and anterior stroma of the cornea. Confocal microscopy images of the cornea showed focal hyper-reflective materials deposited in the subepithelium and anterior stroma. It was confirmed by histopathology that Bowman's membrane was mainly replaced by extracellular fibril material, which extended downwards into the superficial corneal stroma. Molecular genetic analysis revealed a single heterozygous G>T change at nucleotide 124 in exon 4 of TGFBI in all members (22) of the pedigree affected with RBCD, but not in the unaffected members. A p.Arg124Leu mutation of the TGFBI gene was detected in this Chinese pedigree with Reis-Bücklers corneal dystrophy. The phenotype of Reis-Bücklers corneal dystrophy in this family belongs to the geographic type. The molecular genetic studies combined with histopathology may be useful for the accurate diagnosis of this type of corneal dystrophy.

How to tell dystrophies of Bowman's layer (Reis‐Bücklers and Thiel‐Behnke) from one another

Abstract Purpose To discuss difficulties encountered in differentiating two classic dystrophies of the Bowman layer caused by mutations of the TGFBI gene: Thiel–Behnke corneal dystrophy (TBCD) and Reis–Bücklers corneal dystrophy (RBCD). Methods Critical review of published data by the IC3D group and personal experience of the author as an ophthalmic pathologist and clinician. Results It has traditionally been difficult to recognise and distinguish TBCD and RBCD, so much so that some early papers claimed to describe the ultrastructure of RBCD actually analysed tissue from patients with TBCD; the known entity of RBCD was described as an unusual variant of granular corneal dystrophy; and Waardenburg‐Jonkers dystrophy appeared for eyars in textbooks although their patients had TBCD. The main problem is that both dystrophies are fairly rare and clinicians seldom have personal prior experience or adequate literature knowledge of both when they encounter a patient; and the literature with its frequent errors in diagnoses has not been that helpful. Conclusion TBCD and RBCD may be differentiated by careful clinical and ophthalmic pathologic examination if the clinician and pathologist are experienced; genetic or electron microscopic examination is needed for unequivocal confirmation.

Allelic homogeneity in Avellino corneal dystrophy due to a founder effect

Avellino corneal dystrophy (ACD) is a common corneal dystrophy that shows allelic homogeneity, R124H mutation in the transforming growth factor beta-induced (TGFBI) gene. There are distinct phenotypes of homozygous Avellino corneal dystrophy, termed types I and II. To investigate if the difference is caused by a modifier mutation, we sequenced the entire coding region of TGFBI of two types of ACDs. The sequences obtained from each type were identical, and we could not find any nucleotide alternations. Instead, we found seven single nucleotide polymorphisms (SNPs) compared with the normal control. Primer extension analysis revealed that all 14 homozygous patients were homozygotes in each SNP, which meant that all the patients shared the same disease haplotype. Subsequent analysis of 45 heterozygous ACD patients showed strong linkage disequilibrium between disease alleles of each SNP and ACD. These results strongly suggest that the allelic homogeneity of TGFBI associated corneal dystrophies (ACD, lattice corneal dystrophy types I and III, granular corneal dystrophy and Reis-Bucklers dystrophy) might not be caused by mutation hot spots but by the founder effects.

Analysis of gene mutation in Chinese patients with Reis-Bücklers corneal dystrophy

To identify the mutation of the TGFBI gene in Chinese patients with Reis-Bücklers corneal dystrophy, and to study the relationship between the gene mutation and the clinical appearance. Ten patients and 2 unaffected family members from 2 unrelated families with corneal dystrophy were studied. Molecular genetic analysis was performed on DNA extracted from peripheral leucocytes, and exons 4 and 12 of the TGFBI gene were amplified by polymerase chain reaction for direct sequencing. Both pedigrees showed an autosomal dominant inheritance. The clinical appearance of the cornea consisted of fine granular, subepithelial opacities which spread and become confluent with time, and resembled geographic type of Reis-Bücklers corneal dystrophy. Direct sequencing of all affected members revealed a G-to-T transition at codon 124 (CGC to CTC), producing R124L mutation of TGFBI gene. R124L mutation of the TGFBI gene is found in two Chinese families with Reis-Bücklers corneal dystrophy. The phenotype of Reis-Bücklers corneal dystrophy in both families belongs to the geographic type. Molecular genetic approach may be useful for the proper diagnosis of this type of corneal dystrophy.

TGFBI Gene Mutation Analysis in Families with Hereditary Corneal Dystrophies from Ukraine

In our study, 5 previously reported mutations of the TGFBI gene – R124C, R124H, R124L (exon 4), R555W, R555Q (exon 12) – were analyzed using polymerase chain reaction followed by restriction digestion in 48 individuals from 19 unrelated families with different forms of corneal dystrophy from different regions of Ukraine. The R555W mutation was detected in 6 patients from 4 families with granular corneal dystrophy. The R124C mutation was detected in 1 unaffected 10-year-old individual and in 24 patients from 8 families with lattice corneal dystrophy. As far as the R124C mutation detected in 1 patient with clinically diagnosed Reis-Bucklers corneal dystrophy is concerned, we concluded that this patient was misdiagnosed. The obtained results show that TGFBI gene mutation analysis is important as well for the early differential diagnosis of corneal dystrophies and genetic consulting in high-risk families.

The spectrum of beta ig-h3 gene mutations in Japanese patients with corneal dystrophy.

This study was undertaken to identify beta ig-h3 gene mutations in Japanese patients with granular corneal dystrophy (GCD), Avellino corneal dystrophy (ACD), lattice corneal dystrophy (LCD), and Reis-Bücklers' corneal dystrophy (RBCD). R124H, R124C, R555W, and R555Q mutations have been reported in Europe to cause ACD, LCD type I, GCD, and RBCD, respectively. In total, 91 Japanese patients who had been clinically diagnosed with GCD, LCD, or RBCD were investigated to determine whether they had mutations in the beta ig-h3 gene. Genomic DNA was amplified using the polymerase chain reaction and analyzed using single-strand conformation polymorphism techniques. Mutations were identified using the direct sequencing method. In 68 unrelated patients who had been diagnosed with GCD, 62 patients (91%) were found to have the R124H mutation, which has been reported to cause ACD, whereas only six patients (9%) had the R555W mutation. In LCD patients, 10 patients with type I disease had the R124C mutation, and 10 patients with type IIIA disease had a P501T mutation. One patient with atypical LCD had an L527R mutation. In two patients with RBCD, one had an R555Q mutation and the other patient with geographic opacities was found to have an R124L mutation. Depending on the specific mutation in the beta ig-h3 gene, the phenotypes of corneal dystrophy may differ. Our results indicate that assay of mutations in the beta ig-h3 gene is required to establish a correct diagnosis.

Two distinct kerato-epithelin mutations in Reis-Bücklers corneal dystrophy

PURPOSE: Two patients were diagnosed with Reis-Bücklers corneal dystrophy (RBCD), although the pattern and severity of corneal opacification differed. To see whether there was a genetic basis for these phenotypic variations, we analyzed βig-h3, the gene that codes for kerato-epithelin and that contains a mutation (Arg555Gln) that causes RBCD. METHODS: A 30-year-old man with honeycomb-shaped subepithelial opacities in his central cornea and a 25-year-old man with progressive subepithelial geographic opacities were both considered to have RBCD. We isolated genomic DNA from leukocytes of the two patients and their family members and screened for an Arg555Gln kerato-epithelin mutation. Then we analyzed all exons of the gene using the single-strand conformation polymorphism (SSCP) technique to search for any other kerato-epithelin mutations. RESULTS: The patient with honeycomb-shaped opacities had an Arg555Gln kerato-epithelin mutation that caused his RBCD, whereas the patient with geographic opacities did not; instead, he had a new kerato-epithelin mutation (Arg124Leu), which cosegregated with his family members. CONCLUSIONS: The variant of RBCD characterized by honeycomb-shaped opacities is caused by an Arg555Gln kerato-epithelin mutation. On the other hand, a new kerato-epithelin mutation, Arg124Leu, was found to cause the RBCD variant characterized by recurrent epithelial erosions and progressive geographic subepithelial opacification. Codon 124 is a hot spot for kerato-epithelin mutations, where the mutations responsible for three autosomal dominant corneal dystrophies—lattice type I (Arg124Cys), Avellino (Arg124His), and the variant of RBCD with geographic rather than honeycomb opacities (Arg124Leu)—are located.

REIS-B??CKLERS?? CORNEAL DYSTROPHY

The anterior stroma, epithelium, and Bowman's layer have been proposed as the site of primary pathology in Reis-Bücklers' corneal dystrophy (RBCD). Immunofluorescent localization of laminin and bullous pemphigoid antigen (BPA) was compared with the ultrastructure of RBCD. As previously reported, patchy deposition of characteristic "peculiar curly" filaments was found in the supra-Bowman's, subepithelial fibrous tissue. We also recognized areas of early involvement with deposition of this "peculiar curly" material between a distorted epithelial basal lamina and a normal undisturbed Bowman's layer. In normal cornea, laminin and BPA localized to the epithelial basal lamina. In RBCD, laminin and BPA were in a piebald mosaic distribution throughout the aberrant subepithelial fibrous tissue between the basal lamina and the buried Bowman's layer. This indicates that RBCD is an epithelial disease, with the "peculiar curly" material paralleling the distribution of the attachment proteins.