Novel 2336-2337delCT mutation in RP1 gene in a Japanese family with autosomal dominant retinitis pigmentosa

PURPOSE: To determine the frequency and kinds of mutations in the RP1 gene, and to characterize the clinical features of a Japanese family with autosomal dominant retinitis pigmentosa (ADRP) with a novel 2336 to 2337delCT mutation in the RP1 gene. DESIGN: Case reports and results of DNA analysis. METHODS: Mutational screening by direct sequencing was performed on 96 unrelated patients with ADRP. The clinical features were determined by complete ophthalmologic examinations. RESULTS: A novel 2336 to 2337delCT mutation in the RP1 gene was identified in two patients from a Japanese family with ADRP. In addition, three families with ADRP carried a previously reported nonpathogenic Arg1933X mutation. The ophthalmic findings with a 2336 to 2337delCT mutation were similar to those of typical retinitis pigmentosa with rapid progression after age 40 years. CONCLUSIONS: The most common Arg677X mutation in the white population was not found in the Japanese population; instead a novel mutation was found.     

A new Leu253Arg mutation in the RP2 gene in a Japanese family with X-linked retinitis pigmentosa

PURPOSE: To identify the clinical findings in a Japanese family with X-linked retinitis pigmentosa associated with mutation in codon 253 (Leu253Arg) in the RP2 gene. METHODS: Case reports included clinical features and results of fluorescein angiography, electroretinogram, kinetic visual field testing, and DNA analysis. Two affected hemizygotes with retinitis pigmentosa associated with transversion mutations in codon 253 (Leu253Arg) of the RP2 gene and the obligate carriers were examined. RESULTS: A novel Leu253Arg mutation of the RP2 gene was found to cosegregate with retinal degeneration in two affected males and two carriers in female heterozygote in a Japanese family. The ophthalmic findings in hemizygote showed severe retinal degeneration. In the obligate carrier, mild chorioretinal degeneration was observed in both eyes but a tapetal-like reflex of the fundus was not apparent. CONCLUSIONS: The mutation at codon 253 of the RP2 gene is the first mutation reported in a Japanese family. It is concluded that the mutation of the RP2 gene also causes the X-linked retinitis pigmentosa in Japanese patients.     

Variants of RP1 gene in Chinese patients with autosomal dominant retinitis pigmentosa

BACKGROUND: The objective of this study was to determine the frequency and characteristics of mutations in the RP1 gene and to characterize mutations with the clinical features in the Chinese family with autosomal dominant retinitis pigmentosa (ADRP). METHODS: Forty-three affected, unrelated Chinese individuals with ADRP were recruited between 2002 and 2006. Polymerase chain reaction and direct DNA sequencing were used to screen in the entire coding region and splice sites of the RP1 gene. Cosegregation analysis and population frequency studies were performed for patients with identified mutations. The clinical features were determined by complete ophthalmologic examinations. RESULTS: The mutation detectable rate of the RP1 gene in Chinese patients with ADRP was 1/43. A missense mutation, N985Y, was identified in exon 4 of the RP1 gene in 8 affected individuals from a Chinese family with ADRP. The ophthalmic findings with an N985Y mutation were similar to those of typical retinitis pigmentosa with delayed onset after age 40 years and slow progression. In addition, a total of 9 distinct variants were detected in our study population, most of which were RP1 gene polymorphisms; the pathological significance of P903L, a novel missense mutation, was unconfirmed. INTERPRETATION: Mutations in the RP1 gene are relatively rare in Chinese patients with ADRP. In our cases, N985Y mutation segregated with the phenotype from 1 Chinese family with mild and late-onset ADRP, a finding that has not been documented in other races.     

Clinical features of a Japanese family with autosomal dominant retinitis pigmentosa associated with a Thr494Met mutation in the<Emphasis Type="Italic"> HPRP3</Emphasis> gene

Purpose To determine the clinical features of a Japanese family with autosomal dominant retinitis pigmentosa (ADRP) associated with a Thr494Met mutation in the HPRP3 gene.Methods Mutational screening by direct sequencing was performed on 96 unrelated patients with ADRP. The clinical features were determined by visual acuity, slit-lamp biomicroscopy, electroretinography, fluorescein angiography, and kinetic visual field testing.Results A Thr494Met mutation in the HPRP3 gene was found in one family and it cosegregated with ADRP in the three affected members. The ophthalmic findings were those of typical retinitis pigmentosa with rapid progression after 40-years-of-age. One patient also had retinoblastoma as a child.Conclusion We conclude that the Thr494Met mutation in the HPRP3 gene causes ADRP in Japanese patients. This mutation was found in 1% of patients with ADRP in Japan.     

Novel mutation in RP2 gene in two brothers with X-linked retinitis pigmentosa and mtDNA mutation of leber hereditary optic neuropathy who showed marked differences in clinical severity

PURPOSE: To report the identification of a novel mutation of the RP2 gene in two Japanese brothers with X-linked retinitis pigmentosa of a differing clinical severity. The mother was a carrier of both retinitis pigmentosa and optic atrophy. METHODS: The older brother had a severe form of retinitis pigmentosa associated with macular degeneration and total optic atrophy, whereas the younger brother presented typical X-linked retinitis pigmentosa. RESULTS: Each patient exhibited a novel 2-bp insertion at codon 278 in exon 3 of the RP2 gene as well as a 11778 mutation in mitochondrial DNA. This suggests that the older brother may have developed Leber hereditary optic neuropathy as well as retinitis pigmentosa. CONCLUSION: Molecular testing confirmed the clinical diagnosis in each case. However, such testing did not explain the differences in the severity of the ophthalmoscopic findings between the two brothers.     

视网膜色素变性与基因突变

视网膜色素变性 (RP)是常见的致盲性遗传疾病 ,目前已发现有数十个基因的 15 0多个突变位点与其有关。与常染色体显性遗传、常染色体隐性遗传和性连锁遗传相对应的最常见的突变基因分别是视红紫质基因、杆体环鸟苷酸磷酸二脂酶基因和三磷酸鸟苷酸酶调节因子基因 ,其他的突变基因还有盘膜边缘蛋白基因 (常染色体显性遗传 )、杆体环鸟苷酸离子通道基因、RPE6 5基因、视黄醛结合蛋白基因和酪氨酸激酶受体基因 (常染色体隐性遗传 ) ,RP2基因(性连锁遗传 ) ,线粒体DNA细胞色素b基因等 ,每个突变基因对应于人群中不同的RP患者。基因治疗将成为治疗RP的根本方法 ,而对RP突变基因的定位、基因的生物学功能、突变所造成的分子病理机制的深入认识 ,是进行基因治疗的关键。     

Novel C8orf37 Mutations in Patients with Early-onset Retinal Dystrophy,Macular Atrophy,Cataracts, and High Myopia

Purpose: More than 50 genes are reported as causative genes of autosomal recessive (ar) retinitis pigmentosa (RP) and cone-rod dystrophy (CRD). It is challenging to identify causative mutations for arRP and arCRD. The purpose of the present study was to investigate clinical and genetic features of two siblings with early-onset retinal dystrophy.

Methods: Whole-exome sequencing was conducted for the two affected siblings and their unaffected brother and mother from a Japanese family. We performed complete ophthalmic examinations, including visual acuity, funduscopy, visual-field testing, electroretinography and optical coherence tomography.

Results: Whole-exome sequencing analysis identified novel compound heterozygous mutations, a splice site mutation (c.374?+?2T?>?C in intron 4) and a deletion mutation (c.575delC [p.T192MfsX28] in exon 6) of chromosome 8 open reading frame 37 (C8orf37) gene, which encodes a ciliary protein, in both patients. The mother carried the truncating mutation, and the brother carried neither mutation. Ophthalmic examinations revealed diffuse retinal degeneration, macular atrophy, non-recordable electroretinography responses, cataracts, and high myopia in both patients, who could not be diagnosed with either RP or CRD because of the severe retinal degeneration and early onset disease. Longitudinal follow-up of the patients revealed highly progressive retinal degeneration, macular atrophy, and visual field loss.

Conclusions: Recessive C8orf37 mutations have been identified in early to adolescent-onset arRP and arCRD with macular involvement. Our study identified two novel truncating mutations of the C8orf37 gene in siblings with early-onset retinal dystrophy, macular atrophy, cataracts, and high myopia.     

Mutation of human retinal fascin gene (FSCN2) causes autosomal dominant retinitis pigmentosa

PURPOSE: To characterize the clinical features of 14 Japanese patients with autosomal dominant retinitis pigmentosa (ADRP) who were found to have a mutation in the FSCN2 gene. METHODS: Mutation screening by single-strand conformation polymorphism (SSCP) was performed in 120 unrelated patients with ADRP, 200 unrelated patients with autosomal recessive retinitis pigmentosa (ARRP), and 100 patients with simplex RP (SRP). The DNA fragment that showed abnormal mobility on SSCP was sequenced. The clinical features of these patients were determined by visual acuity, slit lamp biomicroscopy, electroretinography, fluorescein angiography, and kinetic visual field testing. RESULTS: A novel 208delG mutation in the FSCN2 gene was identified in 14 patients from four unrelated families with ADRP. The ophthalmic findings were typical of RP. CONCLUSIONS: The findings show that a 208delG mutation in the FSCN2 gene produces ADRP. This mutation was found in 3.3% of the patients with ADRP in Japan, which suggests that it may be relatively common in Japanese patients with ADRP.     

中国人与欧美人USH2A基因突变谱不同

Usher综合征是一种常见的综合征性视网膜色素变性（RP）,为常染色体隐性遗传性疾病,具有临床和遗传高度异质性。迄今已将Usher综合征的致病基因定位了12个染色体位点,确定了其中的9个致病基因。很多研究证实USH2A基因是Usher综合征的主要致病基因,USH2A基因突变还可引起单纯性RP,但国内的一些研究结果发现,中国人USH2A基因突变谱与欧美人不同。中国人RP致病的热点基因谱尚有待进一步研究。     

视网膜色素变性遗传致病基因peripherin/RDS的突变筛选

目的 了解中国视网膜色素变性患者（RP）中peripherin/RDS基因的突变谱及突变率。方法 应用聚合酶链-异源双链-单链构象多态性（PCR-SSCP）及DNA序列分析技术对收集的15个常染色体显性遗传视网膜色谱变性家系和55例散发视网膜色素变性患者peripherin/RDS基因的第一，第二外显子进行检测。结果 15个家系及55例散发患者未检测到peripherin/RDS基因突变。结论 本研究所检测的视网膜色素变性患者与RDS基因无关，显示视网膜色素变性的遗传异质性。     

Mutation screen of the TUB gene in patients with retinitis pigmentosa and Leber congenital amaurosis

TUB is the first identified member of the TULP family of four proteins with unknown function. A spontaneous mutation in murine tub causes retinal degeneration, obesity, and deafness. Mutations in another member of the TULP family, TULP1, are a cause of autosomal recessive retinitis pigmentosa (RP). These findings prompted us to investigate TUB as a candidate gene for RP and Leber congenital amaurosis (LCA). A mutation screen of the entire coding region of the TUB gene in 159 unrelated patients with autosomal recessive RP, 114 unrelated patients with simplex RP, and 21 unrelated patients with LCA uncovered 18 sequence variations. Of these, seven were missense mutations, six were isocoding changes, and five were intronic polymorphisms. All seven missense mutations were identified as heterozygous changes and no defect could be found in the other allele. None of the isocoding variants or intronic polymorphisms are predicted to create or destroy splice donor or acceptor sites based on splice-site prediction software. Although variant alleles of the TUB gene were found, none could be definitively associated with a specific retinal disease.     

Phenotypic intrafamilial variability associated with S212G mutation in the RDS/peripherin gene

PURPOSE: To describe an Italian family in which two separate phenotypes (retinitis pigmentosa and adult onset vitelliform macular dystrophy) are associated with an identical mutation (S212G) in the peripherin/RDS gene. This mutation has already been reported in patients with retinitis pigmentosa, but it has never been previously detected in association with adult onset vitelliform macular dystrophy. METHODS: A 38-year-old woman complained of bilateral mild metamorphopsias and on ophthalmologic examination she showed the clinical phenotype of adult onset vitelliform macular dystrophy. Her 62-year-old mother was clinically diagnosed with a retinitis pigmentosa, with a severe clinical course. RESULTS: In both patients, molecular genetic analysis revealed a 874A-->G transition in the exon 2 of the RDS gene leading to the amino acid change of S212G. CONCLUSIONS: Peripherin/RDS S212G mutation may have damaging effects on the formation and stability of the photoreceptors' disk structure and may be associated with different clinical phenotypes, even in the same family. Intrafamilial phenotypic variability has been reported for other RDS mutations; this supports the possible influence of modifier genes or environmental factors in the clinical expression of RDS gene variants. Moreover, it suggests that in patients with retinal degeneration and peripherin/RDS mutation, caution should be taken both in using molecular genetic results to predict the clinical course of the disease and in offering genetic counseling.     

Analysis of rhodopsin gene in patients with retinitis pigmentosa using allele-specific polymerase chain reaction.

Point mutations within the rhodopsin gene have been found recently in some patients with autosomal dominant retinitis pigmentosa (ADRP). Currently, four types of point mutations at codons 23, 58 and 347 have been identified. The purposes of this study were to establish simple methods for screening patients with retinitis pigmentosa (RP) to detect these point mutations, and to apply these methods to determine if these mutations are found in Japanese patients with RP. Utilizing the polymerase chain reaction (PCR), a one-step method was developed to detect point mutations at codon 23. This method was then applied to screen genomic DNAs from 30 patients with various types of RP, including ADRP, autosomal recessive RP, simplex RP, Leber's congenital amaurosis or Usher's syndrome. Subsequently, point mutations at codons 58 and 347 were detected by restriction enzyme digestion (Dde I or Msp I) of exons 1 and 5 amplified by PCR. To date, no mutations have been found in codons 23 and 58 in Japanese patients. By using the allele-specific PCR, however, two patients from one pedigree of ADRP were confirmed to have a C-to-T transition at the second nucleotide of codon 347, which results in the substitution of leucine for proline. Our findings indicated the availability of this simple method for detecting these point mutations.     

Mutations in the gene coding for the pre-mRNA splicing factor, PRPF31, in patients with autosomal dominant retinitis pigmentosa

PURPOSE: Retinitis pigmentosa is a clinically and genetically heterogeneous disorder. It is characterized by progressive degeneration of the peripheral retina, leading to night blindness and loss of the peripheral visual field. PRPF31 is one of four pre-mRNA splicing factors identified as causing autosomal dominant retinitis pigmentosa, with incomplete penetrance being the unique feature associated with mutations in this gene. The purpose of this study was to identify PRPF31 mutations in a cohort of 118 cases of autosomal dominant retinitis pigmentosa and determine the genotype-phenotype correlation emerging from the spectrum of mutations in this gene. METHODS: Probands with autosomal dominant retinitis pigmentosa underwent ophthalmic evaluation. Blood samples were obtained, genomic DNA was isolated, and PRPF31 exons along with adjacent splice junctions were amplified by PCR and screened by direct sequencing. RESULTS: In the 118 individuals with autosomal dominant retinitis pigmentosa, six mutations were identified, of which four were novel. One previously known splice site mutation was identified in two other apparently unrelated families. CONCLUSIONS: Mutations in PRPF31 causing adRP were present in nearly 5% of a mixed U.K. population. The age of onset and the severity of the disease varied with different mutations. In addition, individuals carrying the same mutation showed a range of phenotypic variation, suggesting the involvement of other modifying genes.     

A novel mutation (I143NT) in guanylate cyclase-activating protein 1 (GCAP1) associated with autosomal dominant cone degeneration

PURPOSE: To identify pathogenic mutations in the guanylate cyclase-activating protein 1 (GCAP1) and GCAP2 genes and to characterize the biochemical effect of mutation on guanylate cyclase (GC) stimulation. METHODS: The GCAP1 and GCAP2 genes were screened by direct sequencing for mutations in 216 patients and 421 patients, respectively, with various hereditary retinal diseases. A mutation in GCAP1 segregating with autosomal dominant cone degeneration was further evaluated biochemically by employing recombinant proteins, immunoblotting, Ca2+-dependent stimulation of GC, fluorescence emission spectra, and limited proteolysis in the absence and presence of Ca2+. RESULTS: A novel GCAP1 mutation, I143NT (substitution of Ile at codon 143 by Asn and Thr), affecting the EF4 Ca2+-binding loop, was identified in a heterozygote father and son with autosomal dominant cone degeneration. Both patients had much greater loss of cone function versus rod function; previous histopathologic evaluation of the father's eyes at autopsy (age 75 years) showed no foveal cones but a few, scattered cones remaining in the peripheral retina. Biochemical analysis showed that the GCAP1-I143NT mutant adopted a conformation susceptible to proteolysis, and the mutant inhibited GC only partially at high Ca2+ concentrations. Individual patients with atypical or recessive retinitis pigmentosa (RP) had additional heterozygous GCAP1-T114I and GCAP2 gene changes (V85M and F150C) of unknown pathogenicity. CONCLUSIONS: A novel GCAP1 mutation, I143NT, caused a form of autosomal dominant cone degeneration that destroys foveal cones by mid-life but spares some cones in the peripheral retina up to 75 years. Properties of the GCAP1-I143NT mutant protein suggested that it is incompletely inactivated by high Ca2+ concentrations as should occur with dark adaptation. The continued activity of the mutant GCAP1 likely results in higher-than-normal scotopic cGMP levels which may, in turn, account for the progressive loss of cones.     

视网膜色素变性1基因在常染色体显性遗传视网膜色素变性家系中的突变分析

目的:研究常染色体显性遗传视网膜色素变性(autosomal dominant retinitis pigmentosa,ADRP)家系中视网膜色素变性1(retinitis pigmentosa-1,RP1)基因的突变特征及其在RP发病机制中的作用。方法:运用聚合酶链反应和直接测序方法,对6个ADRP家系的47例成员和50例对照者进行了RP1基因全编码区和邻近剪切位点的内含子区域序列突变的筛选与检测。运用单因素分析、多因素Logistic回归分析研究RP1基因点突变在RP发病中的作用。结果:ADRP家系成员和对照组RP1基因第4外显子上检测出2个变异位点。在1691和1725密码子存在杂合的两种类型的密码子(S1691P,Ser-Pro,TCT→CCT;Q1725Q,Gln-Gln,CAA→CAG)。ADRP家系成员中Ser-1691-Pro及Gln-1725-Gln位点突变率显著高于正常对照组(χ2=11.202,P<0.05)。结论:RP1基因Ser-1691-Pro及Gln-1725-Gln位点多态性可增高RP的危险性,具有潜在的致病性,考虑为ADRP家系的易感基因。     

Fundus phenotype in retinitis pigmentosa associated with EYS mutations

Purpose: to report phenotypic and genotypic features in a group of autosomal recessive retinitis pigmentosa (arRP) patients associated with EYS mutations.

Methods: we retrospectively reviewed the clinical records and the molecular genetic data of arRP patients carrying mutations in the EYS gene. All the patients underwent a comprehensive opthalmological examination. Additional investigation included color fundus photography, fundus autofluorescence, Goldmann visual field, OCT scans and full-field standard electroretinography.

Results: we studied 10 RP patients (20 eyes) characterized by mutations in the EYS gene. Thirteen different sequence variants in the EYS gene were identified. In total, nine mutations found in our series had not previously been reported in the literature. All patients in our series complained of typical RP symptoms at the onset of the disease, namely night blindness and progressive constriction of the visual field. Visual acuity ranged from light perception to 20/20. Relevant findings reported in our series are Interdigitation-zone (IZ band) involvement, present even in the milder phenotypes and an estimated prevalence of 6.2% of arRP associated with EYS mutations.

Conclusions: we reported the mutation spectrum of a group of EYS-related RP patients including nine novel mutations and the associated clinical phenotypes. Our series is the largest group of EYS-related arRP patients in the Italian population.     

Extensive intrafamilial and interfamilial phenotypic variation among patients with autosomal dominant retinal dystrophy and mutations in the human RDS/peripherin gene.

Clinical phenotypes of patients with mutations in the human RDS/peripherin gene are described. A 67-year-old woman, who carried a 1 base pair deletion in codon 307, presented with typical late onset autosomal dominant retinitis pigmentosa (RP). In another autosomal dominant pedigree, a nonsense mutation at codon 46 caused 'inverse' retinitis pigmentosa-like fundus changes associated with progressive cone-rod degeneration in a 58-year-old man, whereas his 40-year-old son presented with yellow deposits in the retinal pigment epithelial layer resembling a pattern dystrophy, and with moderately reduced rod and cone function, as determined by two colour dark adapted threshold perimetry and electroretinography. It is suggested that both clinical pictures within this latter family may represent manifestations of fundus flavimaculatus. The clinical data of the three patients provide further evidence for the remarkable variety of disease expression within and between families with mutations in the RDS/peripherin gene. Currently, the most comprehensive statement could be that RDS/peripherin mutations are associated either with typical RP or with various forms of flecked retinal disease.     

Intrafamilial phenotypic variability in families with RDS mutations: exclusion of ROM1 as a genetic modifier for those with retinitis pigmentosa

OBJECTIVES: To identify suspected RDS mutations in families in which different people have been identified with either generalised retinal dystrophy or macular dystrophy. METHODS: Two families with a retinal dystrophy were extensively phenotyped and blood was taken for mutation analysis of the RDS (all) and ROM1 (retinitis pigmentosa patients only) genes. RESULTS: A novel p.Trp94X mutation in RDS was found in all three affected members of a two-generation family that was associated with retinitis pigmentosa in the son, pattern dystrophy in the daughter and fundus flavimaculatus in the mother. In the second family, the proband with retinitis pigmentosa carried a p.Arg220Trp mutation. The mother, who was unavailable for mutation screening, had adult vitelliform macular dystrophy. No ROM1 mutations were found in those with retinitis pigmentosa in either family. CONCLUSION: Mutations in RDS can be associated with an intrafamilial variation in retinal disease. The phenotypes range from Stargardt-like macular dystrophy to classic retinitis pigmentosa. Clinical relevance: Intrafamilial phenotypic variation may be due to the presence of environmental or genetic modifying factors. The presence of a modifying-sequence change in the coding region of ROM1 for two people with retinitis pigmentosa from two families with intrafamilial variation in RDS mutation phenotype has been excluded in this study.