Biomedical subjects

Kun Xia

Publications and source records attributed to Kun Xia.

At least 73 records · Page 4Linked to original sources

PubMed2005

[Detection of duplications or deletions of the PMP22 gene using real-time quantitative PCR].

OBJECTIVE: To detect the duplication or deletion of peripheral myelin protein 22(PMP22) gene in Chinese patients with Charcot-Marie-Tooth disease(CMT) or hereditary neuropathy with liability to pressure palsies(HNPP) using real-time quantitative polymerase chain reaction. METHODS: Duplications or deletions of PMP22 gene were detected in 113 CMT cases, 4 HNPP cases and 50 normal controls by using real-time quantitative PCR. RESULTS: Thirty-six of 113 CMT cases had the PMP22 duplication, 4 HNPP cases had the PMP22 deletion. No duplication or deletion was found in 50 normal controls. CONCLUSION: The PMP22 duplication rate in Chinese patients with CMT is 31.9%(36/113). PMP22 deletion is the common cause of HNPP.

Adult↗

PubMed2005

[Splicing site mutation of D19S418 in PRPF-31 gene and its phenotypic characters with autosomal dominant retinitis pigmentosa].

OBJECTIVE: To evaluate the disease-causing gene and phenotypic characters of a large family with autosomal dominant retinitis pigmentosa (adRP). METHODS: Disease status and associated ocular abnormalities of eight patients and six unaffected members who represent different generations of this family were assessed by measurement of visual psychophysics, full-field and multifocal electrophysiology (ERG and mfERG) and funds fluorescent angiography (FFA). The DNA samples of nineteen patients and fifteen unaffected individuals in this family were examined by Genome scanning, linkage analysis and mutation detection to identify coding sequence changes. RESULTS: A case with variable, early onset night blindness before 10 years and visual field loss in their teens was found. Macular dystrophy, progressing to a retinitis pigmentosa phenotype was demonstrated in most adult cases. Both a-wave and b-wave amplitudes of photopic and scotopic full-field ERG were marked reduced and nearly non-detectable, demonstrating severe damage of photoreceptor systems. There were two obligate gene carriers in the family which remained asymptomatic in the clinical. But one of them was found with a minimal RP characteristic and the other was normal by examination of fundus and ERG. An unreported splicing site mutation (IVS5-1G > A) was identified in intron 5- acceptor site of PRPF-31 gene on chromosome 19. ERG and molecular genetic findings were consistent with the reclassification of this disease as an autosomal dominant RP. CONCLUSION: It is a novel splicing site mutation that IVS5-1G > A of D19S418 site in PRFP31, the relative phenotypes by which main displayed type I/diffuse has variable expressivity and complex phenotype.

Adolescent↗

PubMed2005

[Genetic linkage analysis in localizing a gene of autosomal dominant familial dilated cardiomyopathy with conduction defect].

OBJECTIVE: To localize the gene of autosomal dominant familial dilated cardiomyopathy with conduction defect. METHODS: A Chinese family which was diagnosed as dilated cardiomyopathy with conduction defect was studied. Venous blood (3 - 5 mL) from some family members was collected, and genomic DNA was extracted from the blood. Then whole genome wide scan was performed after excluding the known markers on the candidate loci (CMD1A, CMD1 E, CMD1F, and CMD1H) by two-point linkage analysis. RESULTS: No significant evidence for linkage was found in the two point linkage analyses to the known markers in the analyzed family. And the whole genome wide scan showed the maximum LOD score reached 2.68 at marker D3S1614 ( at recombination fraction theta = 0). CONCLUSION: The related gene in this kindred is located on 3q26 other than on CMD1A, CMD1H, CMD1E, and CMD1F.

Adult↗

PubMed2005

[Hotspot of the mutations of keratin 9 gene in a diffuse palmoplantar keratoderma family].

OBJECTIVE: To identify the gene causing diffuse palmoplantar keratoderma in a Chinese pedigree. METHODS: Four normal individuals and 3 patients in a diffuse palmoplantar keratoderma family and 10 unrelated control samples were recruited. The hotspot of the mutations of keratin 9 gene was analyzed by polymerase chain reaction and direct sequencing. RESULTS: We found a G485A transition in ke ratin 9 gene, resulting in the substitution of glutamine for arginine at codon 162 in this diffuse palmoplantar keratoderma family. The mutation was not found in the 10 unrelated control samples and 4 normal individuals. CONCLUSION: The mutation G485A found in keratin 9 gene is the disease-causing mutation in the diffuse palmoplantar keratoderma family.

Base Sequence↗

PubMed2005

[Mutation analysis of DJ1 gene in patients with autosomal recessive early-onset Parkinsonism].

OBJECTIVE: To investigate the mutation characteristics of DJ1 gene in Chinese patients with autosomal recessive early-onset Parkinsonism (AR-EP). METHODS: Mutations of DJ1 gene were screened by polymerase chain reaction combined with DNA direct sequencing in index patients with AR-EP from 11 unrelated families. RESULTS: No pathogenetic mutations in the DJ1 gene were detected in this group. Six intronic DJ1 polymorphisms (IVS1-15T-->C, IVS4+30T-->G, IVS4+45G-->A, IVS4+46G-->A, IVS5+31G-->A, g.168-185del) were found. Three of them (IVS1-15T-->C, IVS4+45G-->A, IVS4+46G-->A) were not reported previously. CONCLUSION: DJ1 mutations were rare in Chinese patients with autosomal recessive early-onset Parkinsonism.

Adolescent↗

PubMed2005

[Construction of the eukaryotic expression vector of MJD1 and its expression in SH-SY5Y cells].

OBJECTIVE: To construct the eukaryotic expression vector of MJD1 with normal copies of CAG trinucleotide repetition and MJD1 with CAG trinucleotide repetition expansion mutation respectively, and to determine whether the polyglutamine expansion in ataxin-3 could lead to the formation of intranuclear aggregation. METHODS: The coding sequence of wild-type MJD1 and mutant MJD1 was amplified by PCR from pAS2-1-MJD20Q and pAS2-1-MJD68Q respectively. After being digested with BamH I and Hind III, the PCR products were inserted into pcDNA3. 1-Myc-His(-) B. The recombinant plasmids pcDNA3.1-Myc-His(-) B-MJD20Q and pcDNA3.1-Myc-His(-) B-MJD68Q were identified by enzyme digestion analysis and DNA sequencing. The recombinant plasmid was transfected into SH-SYSY cells and the expression of MJD1 in the transfected cells was analyzed by Western blot. The immunofluorescence of the transfected cells was examined using a confocal microscope to observe the formation of intranuclear aggregation. RESULTS: Enzyme digestion analysis and DNA sequencing showed that the target gene was cloned into pcDNA3. 1-Myc-His(-) B. The expression of MJD1 in the transfected cells was confirmed by Western blot; The SH-SY5Y cells transfected with pcDNA3. 1-Myc-His(-) B-MJD68Q showed the formation of intranuclear aggregation, but the cells transfected with pcDNA3.1-Myc-His(-) B-MJD20Q did not show such phenomenon. CONCLUSION: The eukaryotic expression vectors of MJD1 has been successfully constructed; The polyglutamine expansion in ataxin-3 could lead to the formation of intranuclear aggregation.

Ataxin-1↗

PubMed2005

[Confirmation of the extra small chromosome in abnormality karyotype by PCR and FISH].

OBJECTIVE: To investigate the source of the extra small chromosome in a patient with karyotype 45,X[115]/46,X + mar[45]/46,XY[29]. METHODS: The SRYgene was detected by PCR, and the chromosome Y probe that labeled with biotin was detected by fluorescence in situ hybridization. RESULTS: SRY gene is detected positive and the mar chromosome showed positive signal with FISH in human chromosome Y probe pool. CONCLUSION: The extra small chromosome is part of the chromosome Y.

Adolescent↗

PubMed2004

Small heat-shock protein 22 mutated in autosomal dominant Charcot-Marie-Tooth disease type 2L.

Charcot-Marie-Tooth (CMT) disease is the most common inherited motor and sensory neuropathy. We have previously described a large Chinese CMT family and assigned the locus underlying the disease (CMT2L; OMIM 608673) to chromosome 12q24. Here, we report a novel c.423G-->T (Lys141Asn) missense mutation of small heat-shock protein 22-kDa protein 8 (encoded by HSPB8), which is also responsible for distal hereditary motor neuropathy type (dHMN) II. No disease-causing mutations have been identified in another 114 CMT families.

Charcot-Marie-Tooth Disease↗

PubMed2004

Confirmation and refinement of a genetic locus of congenital motor nystagmus in Xq26.3-q27.1 in a Chinese family.

Congenital motor nystagmus (CMN), a subtype of nystagmus, may reduce vision or be associated with other, more serious, conditions that limit vision. The genetic basis for CMN is still unknown. To identify a locus for CMN, genotyping and linkage analysis were performed in 22 individuals from a Chinese family with X-linked CMN using markers from X chromosome. The maximum LOD score obtained for microsatellite maker DXS1192 linked the CMN locus in this family to Xq. By haplotype construction the locus for CMN was finally localized to an approximately 4.4-cM region at chromosome Xq26.3-q27.1. The SLC9A6 and FGF13 genes in this region, were selected and screened for mutation in this family, but no mutation was detected.

China↗

PubMed2004

A novel mutation in KCNQ2 gene causes benign familial neonatal convulsions in a Chinese family.

Benign familial neonatal convulsions (BFNC) are a rare autosomal dominant inherited epilepsy syndrome. Two voltage-gated potassium channel genes, KCNQ2 on chromosome 20q13.3 and KCNQ3 on chromosome 8q24, have been identified as the genes responsible for benign familial neonatal convulsions. By linkage analysis and mutation analysis of KCNQ2 gene, we found a novel frameshift mutation of KCNQ2 gene, 1931delG, in a large Chinese family with benign familial neonatal convulsions. This mutation is located in the C-terminus of KCNQ2, in codon 644 predicting the replacement of the last 201 amino acids with a stretch of 257 amino acids showing a completely different sequence. An unusual clinical feature of this family is that the seizures of every patient did not remit until 12 to 18 months. This is the first report of KCNQ2 gene mutation in China.

Base Sequence↗

PubMed2004

A novel PRPF31 splice-site mutation in a Chinese family with autosomal dominant retinitis pigmentosa.

PURPOSE: The autosomal dominant form of retinitis pigmentosa (ADRP) can be caused by mutations in 13 genes and a further locus for which the gene remains to be identified. This study was intended to identify mutations in a large Chinese pedigree with ADRP. METHODS: A genome scan was conducted in the family. The whole coding sequences and the intron-exon boundaries of candidate genes were amplified and sequenced. The reverse transcriptase polymerase chain reaction (RT-PCR) was performed to amplify the mutated mRNA. RESULTS: The strongest evidence of linkage was detected with three adjacent microsatellite markers genotyped between D19S902 and D19S210 on chromosome 19q13.33-13.43. Within the region, a single nucleotide change (G>A) at position -1 of Intron 5 of PRPF31 was found. The consensus AG doublet of the Intron 5 splice acceptor was changed to AA. The mutation co-segregated with the disease phenotype, suggesting that it was the disease-causing mutation in this family. This splicing site mutation is predicted to cause an erroneous splicing of Exon 6. By RT-PCR, we found the mutated nucleotide of Intron 5 (A) and the first nucleotide of Exon 6 (G) was regarded as a new splice acceptor, resulting in 1 bp deletion of the first codon of Exon 6 (GAG-to-AG) at the mRNA level. This change led to a frameshift and truncated protein of 196 amino acids with 56 novel amino acids prior to a premature stop. CONCLUSIONS: A novel splicing mutation (IVS5-1G>A) in the pre-mRNA splicing-factor gene PRPF31 causes retinitis pigmentosa in a large Chinese family. The mutation results in a truncated protein of PRPF31.

Asian People↗

PubMed2004

A susceptibility locus at chromosome 3p21 linked to familial nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) poses one of the serious health problems in southern Chinese, with an incidence rate ranging from 15 to 50/100,000. Chromosome translocation t(1;3) and frequent loss of heterogeneity on short arms of chromosome 3 and 9 have been reported to be associated with NPC, and a genome-wide scan identified an NPC susceptibility locus on chromosome 4p15.1-q12 recently. In our study, we collected samples from 18 families at high risk of NPC from the Hunan province in southern China, genotyped with a panel of polymorphic markers on short arms of chromosomes 3, 9, and 4p15.1-q12. A locus on 3p21 was identified to link to NPC with a maximum logarithm of odds for linkage score of 4.18. Fine mapping located the locus to a 13.6-cM region on 3p21.31-21.2, where a tumor suppressor gene cluster resided. Our findings identified a novel locus for NPC and provided a map location for susceptibility genes candidates. In contrast to a recent study, no significant evidence for NPC linkage to chromosomes 4 and 9 was observed.

China↗

PubMed2004

A new locus for autosomal dominant Charcot-Marie-Tooth disease type 2 (CMT2L) maps to chromosome 12q24.

Charcot-Marie-Tooth disease (CMT) is one of the most common inherited neurological disorders with a prevalence estimated at 1/2500. The axonal form of this disorder is referred to as Charcot-Marie-Tooth type 2 disease (CMT2). Recently, a large Chinese family with CMT2 was found in the Hunan and Hubei provinces of China. The known loci for CMT1A, CMT2D, CMT1B (the same locus is also responsible for CMT2I and CMT2J), CMT2A, CMT2E, and CMT2F were excluded in this family by linkage analysis. A genome-wide screening was then carried out, and the results revealed linkage of CMT2 to a locus at chromosome 12q24. Haplotype construction and analyses localized this novel locus to a 6.8-cM interval between microsatellite markers D12S366 and D12S1611. The maximal two-point LOD score of 6.35 and multipoint LOD score of 8.08 for marker D12S76 at a recombination fraction (theta) of 0 strongly supported linkage to this locus. Thus, CMT2 neuropathy in this family represents a novel genetic entity that we have designated as CMT2L.

Adolescent↗

PubMed2004

Three novel mutations of the spastin gene in Chinese patients with hereditary spastic paraplegia.

BACKGROUND: Hereditary spastic paraplegia is a group of genetically heterogeneous neurodegenerative disorders characterized by progressive spasticity of the lower limbs. The most common form of hereditary spastic paraplegia is caused by mutations in the spastin gene (SPG4), which encodes spastin, an adenosine triphosphatase associated with various cellular activities protein. OBJECTIVE: To investigate the Chinese patients with hereditary spastic paraplegia for mutations in SPG4. METHODS: DNA samples from 31 unrelated patients were analyzed for mutations in SPG4 by single-strand conformation polymorphism analysis and direct sequencing. All DNA samples were screened for mutations by the polymerase chain reaction, followed by electrophoresis and silver staining. Each new variant identified was analyzed in 50 control subjects to determine whether it is a polymorphism or a mutation. RESULTS: Three novel mutations were detected in 4 affected individuals, including 2 missense mutations (T1258A and A1293G) and 1 deletion mutation (1668-1670delCTA). CONCLUSIONS: To our knowledge, this is the first report of SPG4 mutations in the People's Republic of China. The percentage of involved Chinese families with autosomal dominant hereditary spastic paraplegia with an SPG4 mutation is 18% (4/22), lower than the estimated 40% linked to this locus.

Adenosine Triphosphatases↗

PubMed2004

A novel fusion suicide gene yeast CDglyTK plays a role in radio-gene therapy of nasopharyngeal carcinoma.

To investigate a novel suicide gene for nasopharyngeal carcinoma (NPC) therapy, the yCDglyTK gene was constructed by fusing yeast cytosine deaminase (CD) and herpes simplex type 1 thymidine kinase. The expression of the yCDglyTK gene was detected by RT-PCR and Western blotting, and its bioactivity was demonstrated by an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. An animal study was carried out in which BALB/C nude mice bearing yCDglyTK gene-modified tumors were treated with prodrugs and radiation. Our results revealed that the yCDglyTK gene could be expressed in CNE-2 cells in vitro. In MTT analysis, at the transfection rate of 10%, 66% cells were killed. The synergistic effect of CD and TK showed 91% of yCDglyTK-transfected cells were killed with the treatment of 5-fluorocytosine (5-FC) alone, 60% killed with ganciclovir (GCV) alone, and 75% killed with 5-FC and GCV together. In vivo, the tumor volume in all of the four prodrugs and/or radiation-treated groups were significantly different from that in the PBS-controlled group (P<.01); also yCDglyTK+prodrug+radiation group was different from the other three groups (P<.05). Our findings suggested there was a synergistic antitumor effect when combining suicide gene therapy and radiation, and yCDglyTK has potent antitumor efficacy and may be a candidate suicide gene for cancer therapy.

Analysis of Variance↗

PubMed2004

The combination of suicide gene therapy and radiation enhances the killing of nasopharyngeal carcinoma xenographs.

Nasopharyngeal carcinoma (NPC) is very common in Southern China and Southeast Asian countries. To explore a novel and more effective approach to NPC therapy, a combined strategy of suicide genes and radiation was designed in this study. Five suicide gene expression cassettes, yeast CD, yeast CD/UPRT, and yeast CDglyTK gene controlled by CMV, and Egr-1 and a synthetic CMV-enhanced Egr-1 promoter (CE) were constructed in an expression vector p11MS. The expression of suicide genes in NPC CNE-2 cells were detected by RT-PCR and Western blot. The cytotoxicity of suicide gene therapy and radiation were analyzed by MTT assay. An animal study in which yeast CD/UPRT-expressing CNE-2 tumors in nude mice were treated with 5-FC and radiation was also developed. Our results revealed that p11MSCEyCD/UPRT and p11MSCEyCDglyTK are superior over three other constructs in the killing of NPC cells in vitro. We combined suicide gene-expressing tumors, 5-FC treatment, and radiation in vivo and found that the tumors greatly regressed, some disappeared completely in 3 nude mice in the yCD/UPRT group, and a significant difference of tumor volumes was observed between this group and the other four groups (p < 0.05). Our results indicated that suicide gene therapy and radiation have a synergic effect on NPC therapy, and the combined strategy of radiogene therapy is of great potential as a substitute for the traditional method, radiation alone, in NPC therapies.

Animals↗

PubMed2004

[Construction of middle fragment deletion mutant with improved gene splicing by overlap extension].

OBJECTIVE: To construct a phosphatidylinositol 4-kinase beta (PI4K-beta) mutant with the 325th to 373rd amino acid codons deleted, and try to develop a simple method for constructing middle fragment deletion mutant. METHODS: In line with the mechanism of gene splicing by overlap extension(SOE), an additional PCR was used to get the PI4K-beta mutant in which the 325th to 373rd amino acid codons were deleted. Then the mutated gene was cloned into pCMV-Tag4A mammalian expression vector. RESULTS: A mutant with the 325th to 373rd amino acid codons deleted was constructed successfully. CONCLUSION: The improved SOE is a very effective and reliable method to construct middle fragment deletion mutant. It is worthy to be popularized.

1-Phosphatidylinositol 4-Kinase↗

PubMed2004

[A mutation IVS2+1G>A in EXT2 gene causes hereditary multiple exostoses].

OBJECTIVE: To identify the gene causing hereditary multiple exostoses in a Chinese pedigree. METHODS: Linkage analysis was carried out in the family using microsatellite markers on chromosome 8, 11 and 19 respectively. To detect the mutation, the whole coding sequence and the intron-exon boundaries of the candidate gene were amplified and sequenced. The reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to amplify the mutated mRNA. RESULTS: The disease-causing gene of the family was linked to the EXT2 locus on chromosome 11. A mutation IVS2+1G>A was detected in EXT2 and resulting in 221 bp deletion from 316 to 536 of coding sequence(CDS), which was co-segregated with the disease phenotype. This change led to deletion from codon 106 to codon 178 and subsequent 2 nucleotides, producing a frameshift and truncated protein of 125 aa. CONCLUSION: The mutation IVS2+1G>A is the disease-causing mutation in the Chinese pedigree with hereditary multiple exostoses.

Exostoses, Multiple Hereditary↗