Keiko Fujiki

A new L527R mutation of the βIGH3 gene in patients with lattice corneal dystrophy with deep stromal opacities

Abstract Mutations in the βIGH3 gene on chromosome 5q31 cause five distinct autosomal dominant corneal dystrophies: granular Groenouw type I, Reis-Bücklers’, lattice type I and IIIA, and Avellino corneal dystrophies. We present here a new mutation of the βIGH3 gene in patients with late-onset lattice corneal dystrophy manifest as a deep stromal opacity. To test the previously reported R124C, R124H, P501T, R555W, and R555Q mutations of the βIGH3 gene, 30 patients and 11 normal relatives from 16 independently ascertained families with lattice corneal dystrophy, 49 patients and 12 normal relatives from 40 independently ascertained families with other corneal dystrophies, and 40 unrelated normal volunteers, were analyzed. A L527R (CTG/CGG) mutation of the βIGH3 gene was found in 6 unrelated patients with lattice corneal dystrophy. A retrospective review of the patients’ records showed that the opacities were deep in the stromal layer and of late onset. The mutation was a heterozygous single base-pair transversion from T to G of the second nucleotide position of codon 527. This caused the substitution of arginine for leucine. These six patients did not have mutations in codons 124, 501, or 555. The L527R mutation was not detected in the other corneal dystrophies or 40 normal volunteers. Although phenotypic variations in the size and shape of the deposits were found, all patients with the L527R mutation showed deposits deep in the stromal layer. We conclude that there are now at least six different mutations that have been detected in the βIGH3 gene on chromosome 5q31 and that lead to corneal dystrophy.

Clinical features of autosomal dominant retinitis pigmentosa with rhodopsin gene codon 17 mutation and retinal neovascularization in a Japanese patient

A 49-year-old Japanese man had autosomal dominant retinitis pigmentosa with a point mutation in codon 17 of the rhodopsin gene, resulting in a threonine-to-methionine change, and retinal neovascularization in both eyes. Pigmentary degeneration mainly in the inferior area of the fundus, and severe loss in the upper portion of the visual field were observed. Moderately preserved rod and cone functions were demonstrated by electroretinograms. These findings differed from those of Japanese and white patients with autosomal dominant retinitis pigmentosa with a codon 347 mutation and were almost the same as those of white patients with the codon 17 mutation. Our study indicates that phenotypic similarities exist among patients with the same mutation, but of different racial backgrounds. The neovascularization in the right eye diminished over a two-year period in conjunction with the progression of retinal degeneration.

POINT MUTATIONS OF RHODOPSIN GENE FOUND IN JAPANESE FAMILIES WITH AUTOSOMAL DOMINANT RETINITIS PIGMENTOSA (ADRP)

SummaryThe mutations of codon 17, 23, 58, and 347 of rhodopsin gene were investigated in 24 unrelated Japanese families including 33 patients with autosomal dominant retinitis pigmentosa (ADRP). A patient with codon 17 mutation (Thr-17-Met, ACG→ATG) and a family including 4 patients with codon 347 mutation (Pro-347-Leu, CCG→CTG) were detected among them. Their clinical findings were extremely different between the two mutations. The former showed type 2 and the latter showed type 1 ADRP. No mutation of codon 23 and 58 was detected in any families so far analyzed in the present study. Clinical findings associated with the mutation in codon 17 and 347 of the rhodopsin gene show an existence of allelic heterogeneity.

Leu518Pro mutation of the βig-h3 gene causes lattice corneal dystrophy type I

Abstract PURPOSE: To describe a Japanese family with lattice corneal dystrophy type I, which segregates with a novel mutation, Leu518Pro of the βig-h3 gene. METHODS: DNA was extracted from leukocytes in four members (three affected and one unaffected) of a Japanese family with lattice corneal dystrophy type I. Exon 12 of the βig-h3 gene was amplified and analyzed with a molecular biologic method. Clinical data were also collected. RESULTS: Three generations of this family have been positively diagnosed with lattice corneal dystrophy, indicating autosomal dominant inheritance. We found a heterozygous point mutation that segregates with the disease phenotype. It was a single base-pair transition (CTG to CCG, Leu to Pro). CONCLUSIONS: Although it is extremely rare compared with the Arg124Cys mutation of the βig-h3 gene, Leu518Pro mutation of the βig-h3 also causes lattice corneal dystrophy type I.

Analysis of COL8A2 Gene Mutation in Japanese Patients with Fuchs’ Endothelial Dystrophy and Posterior Polymorphous Dystrophy

PurposeTo determine whether Japanese patients with Fuchs’ endothelial corneal dystrophy (FECD) and posterior polymorphous dystrophy (PPMD) carry mutations in the COL8A2 gene, and to investigate the possible pathogenicity of the COL8A2 gene in these corneal dystrophies.MethodsDNA analysis of the COL8A2 gene was performed in 15 unrelated Japanese patients with FECD, and 5 patients with PPMD using polymerase chain reaction and direct sequencing. Mutation screenings were also performed in 36 unrelated normal volunteers as controls, as well as slit-lamp and specular microscopy.ResultsTwo types of heterozygous missense mutations of the COL8A2 gene (R155Q and T502M) in 5 of 15 FECD probands (R155Q, 3/30 chromosomes, 10.0%; T502M, 3/30 chromosomes, 10.0%) were found. No mutation was detected in the coding region of the COL8A2 gene in the remaining 10 patients with FECD nor in any of the 5 patients with PPMD. These two mutations were also found in normal Japanese volunteers (R155Q, 5/72 chromosomes, 6.9%; T502M, 11/70 chromosomes, 15.7%). The chromosomal frequency of the two mutations was not significant between the patients and normal controls.ConclusionsThe R155Q and T502M mutations of COL8A2 may not be the causative defect in the Japanese FECD and PPMD patients examined in this study. Jpn J Ophthalmol 2004;48:195–198

H626R and R124C mutations of the TGFBI (BIGH3) gene caused lattice corneal dystrophy in Vietnamese people

Background/aims: Mutations of the human transforming growth factor β induced gene (TGFBI) were reported to cause lattice corneal dystrophy (LCD) in various nationalities. This study analysed the TGFBI gene in Vietnamese people with LCD. Methods: 13 unrelated families, including 34 patients and 21 unaffected members were examined. 50 normal Vietnamese people served as controls. Blood samples were collected. Genomic DNA was extracted from leucocytes. Analysis of TGFBI gene was performed using the polymerase chain reaction and direct sequencing. Corneal buttons were studied histopathologically. Results: Two clinically distinguishable forms of LCD were revealed: one was typical of LCDI; the other was characterised by the late onset, thick lattice lines, and asymmetry between two eyes. Sequencing of the TGFBI gene revealed R124C mutation in three families and H626R mutation in 10 families. Congo red staining of the H626R-LCD cornea showed amyloid deposits in the subepithelial and stromal layers. Conclusions: R124C and H626R mutations of TGFBI gene caused LCD in Vietnamese people. R124C, a common cause of LCDI in many nationalities, was relatively rare, whereas H626R reported in several white people but not yet in Asians was most common (>75%) in Vietnamese people. Since the phenotype caused by H626R represents a new variant intermediate between LCDI and LCDIIIA, we proposed to consider it as LCD type IIIB.

Corneal dystrophies in Japan

AbstractRecent advances in molecular genetics have increased our understanding of the role of genes. Four autosomal dominant corneal dystrophies (CDs); granular CD (GCD), Avellino CD (ACD), lattice CD (LCD), and Reis-Bücklers CD (RBCD) were mapped to the long arm of chromosome 5 (5q31). These four diseases were shown, in a Caucasian series, to result from different missense mutations in the TGFBI (BIGH3, keratoepithelin) gene. The same mutations were also detected in Japanese patients, from a different ethnic background. Gelatinous drop-like corneal dystrophy (GDLD), on the other hand, which was found in Japanese patients in 1914, is a rare autosomal recessive disorder characterized by corneal amyloidosis. Parents of the patients had a markedly higher frequency of consanguineous marriages than the general population. The gene responsible for GDLD, the membrane component, chromosome 1, surface marker 1 (M1S1) gene was mapped to the short arm of chromosome 1(1p). Four deleterious mutations in this gene were detected in Japanese patients. We review here additional studies on mutations of the TGFBI and M1S1 genes found in Japanese patients. In the TGFBI gene, nine different mutations were detected in Japanese patients with GCD, ACD, LCD, or RBCD. The codons R124 and R555 of the TGFBI gene were hotspots in Japanese patients, of whom many were ACD patients with the R124H mutation. New mutations responsible for LCD were detected in the TGFBI gene of patients with LCD, in addition to the P501T mutation in LCD type IIIA found earlier. These studies showed a clear genotype/phenotype correlation associated with the TGFBI gene. In the M1S1 gene, the Q118X mutation was the most common alteration, and a founder mutation in Japanese GDLD patients, as previously reported. Ninety-two percent of the mutated alleles were the Q118X.

Homozygotic patient with βig-h3 gene mutation in granular dystrophy

Purpose This study investigated patients with granular dystrophy and identified a homozygotic patient and his family with a mutation in the βtig-h3 gene. Methods Genomic DNAs were extracted from leukocytes of the peripheral blood of the pro-band, his parents, and his grandmother. All had granular dystrophy. Genomic DNAs from 50 unrelated normal volunteers were used as controls. Exon 4 of βig-h3 gene was amplified and analyzed by direct sequence. Clinical data were collected. Results A single-base-pair transition was detected. This was a substitution of G to A of the second nucleotide position of codon 124 in the βig-h3 gene that led to a replacement of histidine for arginine (Arg124His, CGC->CAC). This mutation was the precise one previously reported for Avellino dystrophy. Although the proband was homozygotic for the mutant alleles, his grandmother, and parents were heterozygotic for these alleles. No sequence modification in the codon 124 from 50 nonaffected control individuals was detected. Clinical findings of the proband were severe. Keratectomies were performed for both his eyes 5 times for a 24-year period. His grandmother and parents showed mild clinical symptoms, had a few annular granules in the subepithelial stroma, and maintained good visual acuities. Conclusion Arg124His mutation of the βig-h3 gene was found in a pedigree with granular dystrophy. This mutation was the precise one previously reported for Avellino dystrophy. This fact shows an existence of Avellino form in Japanese. Homozygotic patient for mutant gene showed severe symptoms and an early onset.

Late-onset form of lattice corneal dystrophy caused by leu527Arg mutation of the TGFBI gene.

Purpose. To report two Japanese patients who were clinically diagnosed with late-onset and sporadic lattice corneal dystrophy (LCD) in whom a Leu527Arg mutation in the TGFBI gene was found. Methods. Molecular genetic analysis was performed on DNA extracted from peripheral leukocytes from the patients. Exons 4, 11, and 12 of the TGFBI gene were amplified by polymerase chain reaction and directly sequenced. Histopathologic study was performed on the corneal tissue obtained during deep lamellar keratoplasty (DLK) from one of the patients. Results. Patient 1 was a 74-year-old man who noticed a visual disturbance at the age of 72 years. Deep stromal opacities with nodular deposits and thick lattice lines were observed only in the right cornea, and DLK was performed. Patient 2 was an 82-year-old man who had LCD (similar in appearance to that in patient 1) in both eyes without visual disturbance. Neither of the patients had a family history of corneal problems and had no episode of corneal erosion. A heterozygous single base-pair transition (CTG to CGG, leucine to arginin) was detected in codon 527 of the TGFBI gene in both patients. No mutation was found in codons 124, 501, 518, 546, or 555. Histopathologically, relatively large amyloid deposits in the deep corneal stroma and ribbons of amyloid deposits just beneath the Bowmans layer were observed in the corneal tissue of patient 1. Conclusions. Clinical features and pathologic findings of the late-onset form of LCD with an L527R mutation in the TGFBI gene were made clear.

Six different mutations of TGFBI (betaig-h3, keratoepithelin) gene found in Japanese corneal dystrophies.

Purpose. To investigate mutations of the human transforming growth factor beta-induced gene (TGFBI), transforming growth factor–beta-induced gene product (&bgr;ig-h3, keratoepithelin), in Japanese patients with Avellino corneal dystrophy (ACD), lattice corneal dystrophy (LCD), granular corneal dystrophy (GCD), and Reis-Bücklers corneal dystrophy (RBCD). Methods. Genomic DNA was extracted from the peripheral blood of 75 patients and 7 unaffected relatives from 60 families with ACD, 34 patients and 8 unaffected relatives from 21 families with LCD, 4 patients and 4 unaffected relatives from 4 families with GCD, and 4 patients and an unaffected relative from 3 families with RBCD. Fifty normal volunteers served as controls. Exons 4, 11, and 12 of the TGFBI gene were amplified by polymerase chain reaction and were directly sequenced. Results. Six different heterozygous missense mutations were detected in codons R124, L518, L527, and R555 of the TGFBI gene in the 117 patients from 88 families. A R124H mutation was detected in the patients with ACD. A R124C mutation was detected in the patients with LCD type 1 (LCD1), L518P was in atypical LCD1, and L527R in LCD with opacities deep in stroma. A R555W mutation was detected in the patients with GCD. A R555Q mutation was detected in the patients with RBCD. Conclusions. We conclude that codons R124 and R555 of the TGFBI gene are also hot spots in Japanese patients with ACD, LCD, GCD, and RBCD. Many Japanese patients with CD had ACD with R124H mutation. GCD with R555W mutation was rare.