Optic atrophy,hereditary／diagnosis; Polymerase chain reaction; DNA,mitochondrial; Point mutation; Sequence analysis
Objective Molecular cloning of rat retinal degeneration slow(RDS)gene cDNA. Methods Using PolyA+RNA from retina of SD rat as template,a 1555bp positive cDNA band was obtained by RT-PCR and subcloned into pBluescriptⅡKS(+) vector.The cloned fragment was analyzed with restriction endonucleases and sequencing. Results It had been proved that the cloned fragment was rat RDS/peripherin cDNA.Except for the substitute of A1242G and CA1409-1411CCA,the other sequences corresponded to that reported by Begy. Conclusion Rat RDS/peripherin cDNA was obtained.Researches on function of rat RDS/peripherin gene and its role in retinal degeneration are under way. (Chin J Ocul Fundus Dis,1999,15:97-99)
PURPOSE:To investigate the status and detailed structure of Rb gene in primary tumors and somatic cells of patients with retinoblastoma. To identify the character, origin and transmission of oncogenie point mutations. METHODS:DNA hybridization,SSCP analysis and PCR-associated direct sequencing. RESULTS:Among 108 RB patients examined 80 cases were found to have subtle alterations affecting Rb locus,including 44 cases with homozygous Rb point mutations, 20 cases with two independent heterozygous Rb point mutations, 16 cases with heterozygous mutations involved in one allele of Rb gene. Majority of bilateral RB patients and a small fraction of unilateral RB patients were detected to have a germline mutation. In addition the higher frequency of new germline mutation and parental origin of mutation were observed. CONCLUSION :Rb gene is closely associated with retinoblastoma. Two mutation events and resulting inaetivations of both Rb alleles are required for RB tumorigenesis. Based on our own data,the first event is exclusively point mutation. As for the second event,LOH accounts for two third of cases,point mutation for one third of cases. （Chin J Ocul Fundus Dis,1997,13: 12- 16）
ObjectiveTo construct eukaryotic expression vector of pEGFP-N3-TFPI-2, and to provide the base of studying the function of TFPI-2 gene. MethodsExtraction of total RNA from placental tissue was extracted at first, and then reverse transcriptase synthesis of cDNA was carried out. The cDNA fragment of TFPI-2 gene which was obtained by real time PCR (RT-PCR) was inserted into eukaryotic expression vector of pEGFP-N3. After double digestion with XhoⅠand KpnⅠ, the recombinant vector of pEGFP-N3-TFPI-2 was identified in 1% agarose gel electrophoresis and was tested by the sequence analysis. Then, the recombinant vector of pEGFP-N3-TFPI-2 (transfection group) and vector of pEGFP-N3 (blank control group) were transfected into Top10 competent cells with LipofectamineTM 2000, but no transfection-related treatment was performed in cells of untransfection group. Western blot method was used to test the expression of TFPI-2 protein in cells of 3 groups. ResultsThe purity of total RNA which were analysis by agarose gel electrophoresis and spectrophotometry were fit for PCR. After coding of TFPI-2 gene fragment and eukaryotic expression vector of pEGFP-N3, the recombinant plasmid of pEGFP-N3-TFPI-2 were got double digestion with XhoⅠand KpnⅠ, and was identified in 1% agarose gel electrophoresis, of which showing that there were 2 specific amplification of strips at 708 bp and 4 700 bp. Result of sequence analysis confirmed that the size of recombinant vector was consistent with the theoretical value. Results of Western blot showed that the expression of TFPI-2 protein in transfection group (0.657 3±0.032 5) was higher than those of blank control group (0.301 7±0.028 7) and untransfection group (0.314 3±0.026 6), P < 0.01. ConclusionsThe eukaryotic expression vector of pEGFP-N3-TFPI-2 has been constructed successfully, which laiding the foundation for the analysis about function of TFPI-2 gene.
ObjectiveTo reveal the pathogenic mutation in a three-generation Chinese family with autosomal dominant familial exudative vitreoretinopathy (FEVR). MethodsThree patients and a healthy spouse from the index family with FEVR were recruited. The proband was a 5 years old boy. His mother and grandpa were presented with typical FEVR presentations, while his father with normal ocular fundus. DNA was extracted from peripheral blood samples taken from all four participants. All coding and exon-intron boundary regions of five targeted genes, including NDP, FZD4, LRP5, TSPAN12 and ZNF408 were amplified with polymerase chain reaction and sequenced using direct sequencing. In silico analyses were applied to determine the conservation of the mutation site, pathogenic effect and the potential protein crystal structural changes caused by the mutation. ResultsFZD4 c.478G > A, a susceptible mutation was found after four high frequency mutation sites which MAF values were higher than 0.001 was filtered among 5 single nucleotide variations detected in four participants, leading to the residue 160 changing from glutamate to lysine (p.E160K). Co-segregation analysis between genotypes and phenotypes revealed FZD4 p.E160K as the disease-causing mutation for this family. Conservational analysis suggested that this mutation site was highly conserved among all tested species. Functional analysis predicated that this mutation may be a damaging mutation. Crystal structural analysis also indicated that this mutation could lead to the elimination of the hydrogen bond between residue 160 and asparagine at residue 152, thus altering the tertiary structure of the protein and further impairing the protein function. ConclusionOur study demonstrates FZD4 p.E160K as a novel pathogenic mutation for FEVR.
ObjectiveTo identify the pathogenic genes and mutations in a family with Usher syndrome type 2.MethodsA three-generation family including 7 individuals was enrolled in this study. There were 2 male patients and 5 unaffected individuals. All participants was underwent related ophthalmologic examination, including best corrected visual acuity, slit-lamp, indirect ophthalmoscopy, electroretinogram (ERG), optical coherence tomography and visual field test. DNA was extracted from 3 ml peripheral venous blood of all participants. A total of 136 hereditary retinal disease target genes were screened and the DNA sequence was performed by Next-generation sequence analysis. Then the suspected mutations compared with databases to identify the suspected mutations, which should be verified with non-affected family members and 100 normal subjects by PCR and Sanger sequence.ResultsThe sequence result showed that 2 patients, the proband and his brother, carried complex heterozygous mutations in the USH2A gene: c.5459T＞C (p.M1820T) in exon 27, c.802G＞A (p.G268R) in exon 5 and c.1190T＞A (p.I397K) in exon 7. The c.5459T＞C and c.1190T＞A mutations in USH2A have not been reported in the literature and database. Although their mother carried c.5459T＞C (p.M1820T) and c.802G＞A (p.G268R), and their father carried c.1190T＞A (p.I397K) heterozygous mutations, the parents did not present phenotype. These mutations were not detected in other normal family members. The result was supported by co-segregation analysis.ConclusionThe heterozygous mutations c.5459T＞C (p.M1820T), c.1190T＞A (p.I397K) and c.802G＞A (p.G268R) in USH2A gene cause Usher syndrome in this family.
ObjectiveTo identify mutations in NDP, FZD4, LRP5, TSPAN12 in Chinese families with familial exudative vitreoretinopathy (FEVR) and observe the clinical features.MethodsRetrospective case series study. The 9 patients (18 eyes) and 5 normal members from 4 unrelated families were included in the study. The patients medical history and family history were collected in detail. All patients underwent best corrected visual acuity (BCVA), slit-lamp biomicroscopy, fundus colorized photography, fundus fluorescein angiography (FFA). Genomic DNA were collected from all the patients. Mutations were detected by directly sequencing to the whole coding region and exon-intron boundaries of NDP, FZD4, LRP5 and TSPAN12 gene. Polyphen and SIFT programs were used to predict the effects on the structure and functional properties of mutant protein.ResultsThere were two affected individuals in the family 2 carried LRP5 gene mutation [c.1330C＞T (p.R444C )] in exon 6 by sequence analysis. A score of 0.882 was acquired by Polyphen program analysis. And the missense change was predicted to be pathogenic by SIFT. Fundus changes of the proband showed angioplasia, tortuosity of peripheral vessels. And temporal dragging of the optic disc, peripheral avascular zone, neovascularization were found in FFA. Brush-like and straight of peripheral vessels were found in Ⅰ1. No variant was found in NDP, FZD4 and TSPAN12 gene.ConclusionOur study supports the gene mutation c.1330C＞T (p.R444C) of LRP5 is pathogenesis of FEVR. Patients with the same mutation could have variable phenotypic characteristics.
The severe acute respiratory syndrome coronavirus 2 is characterized by a long incubation period, strong infectivity and general susceptibility to the population. At present, there are no specific medicines that can treat coronavirus disease 2019. In order to increase the understanding of the molecular biology of severe acute respiratory syndrome coronavirus 2 and try to find effective treatments, we used SnapGene Viewer to analyze the genomic sequences of five strains of severe acute respiratory syndrome coronavirus 2 that published by National Genomics Data Center. The results showed that the genome length of this virus was about 29.8 kb and twelve open reading frames were predicted, and five nucleotide change sites were found in the open reading frames. In addition, we analyzed drugs used during the outbreak of severe acute respiratory syndrome, current drugs for the treatment of coronavirus disease 2019 and other possible drugs, to find some possible medicines with clinical treatment effects.