Screening for, andVariants in a Cohort of Chinese Patients with Charcot-Marie-Tooth / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>SH3TC2, PMP2, and BSCL2 genes are related to autosomal recessive (AR) Charcot-Marie-Tooth (CMT) disease type 1, autosomal dominant (AD)-CMT1, and AD-CMT2, respectively. Pathogenic variants in these three genes were not well documented in Chinese CMT patients. Therefore, this study aims to detect SH3TC2, PMP2, and BSCL2 pathogenic variants in a cohort of 315 unrelated Chinese CMT families.</p><p><b>METHODS</b>A total of 315 probands from 315 unrelated Chinese CMT families were recruited from the Department of Neurology of Third Xiangya Hospital and Xiangya Hospital. We screened for SH3TC2 pathogenic variants in 84 AR or sporadic CMT probands, PMP2 pathogenic variants in 39 AD or sporadic CMT1 probands, and BSCL2 pathogenic variants in 50 AD or sporadic CMT2 probands, using polymerase chain reaction and Sanger sequencing. All these patients were out of 315 unrelated Chinese CMT families and genetically undiagnosed after exclusion of pathogenic variants of PMP22, MFN2, MPZ, GJB1, GDAP1, HSPB1, HSPB8, EGR2, NEFL, and RAB7. Candidate variants were analyzed based on the standards and guidelines of American College of Medical Genetics and Genomics (ACMG). Clinical features were reevaluated.</p><p><b>RESULTS</b>We identified three novel heterozygous variants such as p.L95V (c.283C>G), p.L1048P (c.3143T>C), and p.V1105M (c.3313G>A) of SH3TC2 gene and no pathogenic variants of PMP2 and BSCL2 genes. Although evaluation in silico and screening in the healthy control revealed that the three SH3TC2 variants were likely pathogenic, no second allele variants were discovered. According to the standards and guidelines of ACMG, the heterozygous SH3TC2 variants such as p.L95V, p.L1048P, and p.V1105M were considered to be of uncertain significance.</p><p><b>CONCLUSIONS</b>SH3TC2, PMP2, and BSCL2 pathogenic variants might be rare in Chinese CMT patients. Further studies to confirm our findings are needed.</p>

Linkage analysis of susceptibility loci in 2 target chromosomes in pedigrees with paranoid schizophrenia and undifferentiated schizophrenia / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the relationship of susceptibility loci in chromosomes 1q21-25 and 6p21-25 and schizophrenia subtypes in Chinese population.</p><p><b>METHODS</b>A genomic scan and parametric and non-parametric analyses were performed on 242 individuals from 36 schizophrenia pedigrees, including 19 paranoid schizophrenia and 17 undifferentiated schizophrenia pedigrees, from Henan province of China using 5 microsatellite markers in the chromosome region 1q21-25 and 8 microsatellite markers in the chromosome region 6p21-25, which were the candidates of previous studies. All affected subjects were diagnosed and typed according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revised (DSM-IV-TR; American Psychiatric Association, 2000). All subjects signed informed consent.</p><p><b>RESULTS</b>In chromosome 1, parametric analysis under the dominant inheritance mode of all 36 pedigrees showed that the maximum multi-point heterogeneity Log of odds score method (HLOD) score was 1.33 (α = 0.38). The non-parametric analysis and the single point and multi-point nonparametric linkage (NPL) scores suggested linkage at D1S484, D1S2878, and D1S196. In the 19 paranoid schizophrenias pedigrees, linkage was not observed for any of the 5 markers. In the 17 undifferentiated schizophrenia pedigrees, the multi-point NPL score was 1.60 (P= 0.0367) at D1S484. The single point NPL score was 1.95(P= 0.0145) and the multi-point NPL score was 2.39 (P= 0.0041) at D1S2878. Additionally, the multi-point NPL score was 1.74 (P= 0.0255) at D1S196. These same three loci showed suggestive linkage during the integrative analysis of all 36 pedigrees. In chromosome 6, parametric linkage analysis under the dominant and recessive inheritance and the non-parametric linkage analysis of all 36 pedigrees and the 17 undifferentiated schizophrenia pedigrees, linkage was not observed for any of the 8 markers. In the 19 paranoid schizophrenias pedigrees, parametric analysis showed that under recessive inheritance mode the maximum single-point HLOD score was 1.26 (α = 0.40) and the multi-point HLOD was 1.12 (α = 0.38) at D6S289 in the chromosome 6p23. In nonparametric analysis, the single-point NPL score was 1.52 (P= 0.0402) and the multi-point NPL score was 1.92 (P= 0.0206) at D6S289.</p><p><b>CONCLUSION</b>Susceptibility genes correlated with undifferentiated schizophrenia pedigrees from D1S484, D1S2878, D1S196 loci, and those correlated with paranoid schizophrenia pedigrees from D6S289 locus are likely present in chromosome regions 1q23.3 and 1q24.2, and chromosome region 6p23, respectively.</p>

A novel candidate locus on chromosome 11p14.1-p11.2 for autosomal dominant hereditary spastic paraplegia / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Hereditary spastic paraplegia (HSP) is a group of inherited neurodegenerative disorders with the shared characteristics of slowly progressive spasticity and weakness of the lower limbs. Thirteen loci for autosomal dominant HSP have been mapped.</p><p><b>METHODS</b>A Chinese family with HSP was found in the Shandong province and Inner Mongolia Autonomous Region of China and genomic DNA of all 19 family members was isolated. After exclusion of known autosomal dominant loci, a genome wide scan and linkage analysis were performed.</p><p><b>RESULTS</b>The known autosomal dominant loci of SPG3A, SPG4, SPG6, SPG8, SPG9, SPG10, SPG12, SPG13, SPG17, SPG19, SPG29, SPG31 and SPG33 were excluded by linkage analysis. The results of a genome wide scan demonstrated candidate linkage to a locus on chromosome 11p14.1-p11.2, over an 18.88 cM interval between markers D11S1324 and D11S1933. A maximal, two point LOD score of 2.36 for marker D11S935 at a recombination fraction (theta) of 0 and a multipoint LOD score of 2.36 for markers D11S1776, D11S1751, D11S1392, D11S4203, D11S935, D11S4083, and D11S4148 at theta=0, suggest linkage to this locus.</p><p><b>CONCLUSION</b>The HSP neuropathy in this family may represent a novel genetic entity, which will facilitate discovery of this causative gene.</p>

Mutation screening of MLH1 and MSH2 genes in two Chinese families with hereditary nonpolyposis colorectal cancer / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify the MLH1 and MSH2 gene mutation in two hereditary nonpolyposis colorectal cancer (HNPCC) families.</p><p><b>METHODS</b>Polymerase chain reaction and DNA sequencing were used to screen for MLH1 and MSH2 gene mutation, and PCR-restriction fragment length polymorphism and DNA sequencing were performed to confirm the mutation.</p><p><b>RESULTS</b>By DNA sequencing, a novel mutation of c.243_244insA located at the exon 3 of MLH1 gene was detected in family A, while c.1215_1218dupCCGA mutation located at the exon 7 of MSH2 gene was detected in family B. These two mutations can cause the formation of premature proteins.</p><p><b>CONCLUSION</b>The novel mutations c.243_244insA in MLH1 gene and c.1215_1218dupCCGA in MSH2 gene were the disease-causing mutations in the two HNPCC families.</p>

Denaturant gradient gel electrophoresis in the genetic diagnosis of hereditary multiple exostoses / 中南大学学报(医学版)

OBJECTIVE@#To detect the mutations of EXT2 gene in hereditary multiple exostoses (HME) families and to investigate the sensitivity of denaturant gradient gel electrophoresis (DGGE) in screening the mutations in EXT2 gene.@*METHODS@#Five HME families and 3 sporadic patients were screened for the mutation detection in all exons of EXT2 gene covering the coding sequence and the flanking intronic sequence by DGGE, and DNA sequencing was performed for products with abnormal conformation.@*RESULTS@#Among these HME patients, we found 2 disease-causing mutations: A313T (nonsense mutation) and 319 insGT (frameshift mutation).@*CONCLUSION@#Two mutations of EXT2 gene are identified in the sample. DGGE can be an ideal choice for gene diagnoses of HME.

Novel mutation of Y271H in EXT1 gene causes multiple exostoses / 中南大学学报(医学版)

OBJECTIVE@#To explore the disease associated gene mutation of multiple exostoses by family analysis.@*METHODS@#Polymerase chain reaction and DNA sequencing were used to detect the mutation hot spot regions of EXT1 and EXT2 gene, while restriction fragment length polymorphism was performed to screen the mutation.@*RESULTS@#We found a novel heterozygous mutation c.811T ->C in EXT1 gene of patients, which resulted in the substitution of histidine for tyrosine at codon 271 in this hereditary multiple exostoses family. The mutation was not found in the unaffected family members, nor in the 100 unrelated normal individual, which was unreported before.@*CONCLUSION@#The novel mutation Y271H is the disease-causing mutation in the hereditary multiple exostoses family.

Two novel mutations of the LDL receptor gene associated with familial hypercholesterolemia in a Chinese family / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Familial hypercholesterolemia (FH) is a type of dominant autosomal disease that causes high levels of plasma low-density lipoprotein cholesterol (LDL-C). In the past years, molecular data related to FH were limited in China. Now, to gain more information about FH, we analyzed one proband with a severe FH phenotype as well as his relatives.</p><p><b>METHODS</b>After the entire coding sequence and the intron-exon junctions of the low-density lipoprotein receptor (LDLR) gene were amplified using PCR, we sequenced the LDLR gene of a Chinese FH family. RT-PCR was used to detect changes in the mRNA.</p><p><b>RESULTS</b>Two novel mutations were identified in the LDLR gene of this family. One, W165X, was a G > A substitution at the third nucleotide of codon 165. The other, IVS5-1G > A, was also a G > A substitution at the acceptor splice site of intron 5. The most striking discovery is that the proband was heterozygous for W165X but homozygous for IVS5-1G > A. The cDNA sequencing showed that the IVS5-1G > A mutation caused the insertion of 10 nucleotides, namely GCTCTCACAA, between exon 5 and exon 6.</p><p><b>CONCLUSIONS</b>The two nucleotide variations are thought to be the FH-causing mutations because the co-segregation of the mutant allele with the phenotype of FH has been shown in this Chinese family. These data show an increase in the mutational spectrum of FH in China and verify a scarce mutational form in the LDLR gene.</p>

Mapping of pathogenic genes in a pedigree with autosomal dominant ichthyosis vulgaris / 中国医学科学院学报

<p><b>OBJECTIVE</b>To elucidate the pathogenic genes in a pedigree with autosomal dominant ichthyosis vulgaris (IV).</p><p><b>METHODS</b>Linkage analysis was performed by using STR markers in chromosome 1, and mutation detection was used to screen for FLG gene mutation.</p><p><b>RESULTS</b>A maximum two-point Lod score of 3.46 (theta=0) was obtained at D1S2696. Haplotype analysis placed the critical region in a 15-CM interval defined by D1S2726 and D1S305, but no mutation of FLG was found in our IV patients.</p><p><b>CONCLUSION</b>The pathologic gene of the IV family locates near D1S2696, and the FLG gene may not ruled out from the pathologic genes.</p>

A mutation 1633-26(C-->A) in EXT1 gene causes multiple exostoses / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the gene mutation in a patient with multiple exostoses, identify the disease-causing gene mutation.</p><p><b>METHODS</b>Polymerase chain reaction and DNA sequencing were used to screen the EXT1 or EXT2 gene mutation, while mismatch primer amplification and restriction endonuclease digestion were performed to confirm the mutation.</p><p><b>RESULTS</b>By DNA sequencing, a mutation in the seventh intron was detected and located at 26 bp of 3' splice site upstream in EXT1 gene, which was unreported before. Mismatch primer amplification and restriction fragment length polymorphism analysis suggested that this mutation was not detected in the normal control.</p><p><b>CONCLUSION</b>The mutation 1633-26(C-->A) may be the disease-causing mutation in this patient with multiple exostoses.</p>

Cloning to rule out 10 candidate genes located in chromosome 12q24 for Charcot-Marie-Tooth disease type 2L / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To clone the disease-causing genes possibly existing in 6.8 cM distance between microsatellite markers D12S1720 and D12S1611 in chromosome 12q24 for Charcot-Marie-Tooth disease type 2L (CMT2L).</p><p><b>METHODS</b>Ten positional and functional candidate genes were chosen among all known genes in this locus region by bioinformatics inqury. Mutation detection was performed by sequencing the exons and intron-exon junctions of the candidate genes.</p><p><b>RESULTS</b>Eleven sequence variations, that included 5 heterozygous and 6 homozygous variations, were detected in the exons and flanking areas of the 10 candidate genes. All the variations showed no co-segregation with disease phenotype.</p><p><b>CONCLUSION</b>Ten candidate genes(TAOK3, RAB35, RPLP0, PXN, RNF10, RHOF, VPS33A, RSN, DENR, RNP24) were ruled out as the disease-causing gene for CMT2L. Ten single nucleotide polymorphisms (SNP) were reported for the first time.</p>

Genetic linkage analysis in localizing a gene of autosomal dominant familial dilated cardiomyopathy with conduction defect / 中南大学学报(医学版)

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.

Hotspot of the mutations of keratin 9 gene in a diffuse palmoplantar keratoderma family / 中南大学学报(医学版)

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.

Mutation analysis of small heat-shock protein 22 gene in Chinese patients with Charcot-Marie-Tooth disease / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the characteristics of the mutation of small heat-shock protein 22 (HSP22) gene in Chinese patients with Charcot-Marie-Tooth (CMT) disease.</p><p><b>METHODS</b>A CMT2L proband with 423(G--> T) mutation in HSP22 gene had been studied and reported by the present authors. In this study, mutation analysis of HSP22 gene was performed using polymerase chain reaction and DNA direct sequencing in 114 CMT probands.</p><p><b>RESULTS</b>In the 114 CMT probands, a 582(C--> T)(T194T)samesense mutation was found in two unrelated families.</p><p><b>CONCLUSION</b>The rate of HSP22 gene mutation in Chinese patients with CMT is as low as 0.87%(1/115).</p>

Mutation analysis of small heat shock protein 27 gene in Chinese patients with Charcot-Marie-Tooth disease / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the features of small heat shock protein 27 (HSP27) gene mutation in Chinese patients with Charcot-Marie-Tooth disease (CMT).</p><p><b>METHODS</b>DNA samples from 114 CMT probands were screened for mutations in HSP27 gene by polymerase chain reaction and direct sequencing, and haplotype analysis was further carried out on the mutation detected families.</p><p><b>RESULTS</b>One missense mutation C379T was detected in 4 autosomal dominant CMT2 families. Haplotype analysis indicated that the 4 families probably had a common ancestor.</p><p><b>CONCLUSION</b>To the authors' knowledge, this is the first report of HSP27 gene mutation in Chinese patients with CMT, but it may be not common(0.90%). The C379T mutation in HSP27 gene also causes CMT2 except for distal hereditary motor neuropathy, thus providing further evidence that even the same mutation in the same gene may lead to distinct phenotypes.</p>

Mutation analysis of ganglioside-induced differentiation associated protein-1 gene in Chinese Charcot-Marie-Tooth disease / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the mutation feature of ganglioside-induced differentiation associated protein-1 (GDAP1) gene in Chinese Charcot-Marie-Tooth disease(CMT) patients.</p><p><b>METHODS</b>Mutation analysis was carried out by use of polymerase chain reaction-single strand conformation polymorphism(PCR-SSCP) combined with DNA direct sequencing of the six exons and their flanking regions of GDAP1 gene in twenty-three CMT patients, including 8 probands of autosomal recessive CMT families and 15 sporadic patients.</p><p><b>RESULTS</b>A compound heterozygous mutation A533G and A767G were unveiled in one autosomal recessive CMT kindred. The homozygous and heterozygous T507G were common SNPs in Chinese population.</p><p><b>CONCLUSION</b>A533G and A767G of GDAP1 gene were new mutations firstly reported.</p>

Mutation analysis of keratin 9 gene in a pedigree with epidermolytic palmoplantar keratoderma / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify mutations of keratin 9 (KRT9) gene in a big Chinese family with epidermolytic palmoplantar keratoderma(EPPK) combined with knuckle-pad-like lesions and nail lesions.</p><p><b>METHODS</b>Genomic DNA from peripheral blood of all available members in this family and 50 unrelated healthy individuals was used for amplification of the whole coding sequence and the intron-exon boundaries of KRT9 gene by PCR; The mutation was detected by direct sequence analysis and identified by restriction endonuclease Dde I.</p><p><b>RESULTS</b>A mutation of AAT>AGT at codon 160 (N160S) was found in all patients but not in unaffected family members and 50 controls.</p><p><b>CONCLUSION</b>The mutation of AAT>AGT at codon 160 (N160S) is the disease-causing mutation in this Chinese pedigree with EPPK.</p>

A mutation IVS2+1G>A in EXT2 gene causes hereditary multiple exostoses / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify the gene causing hereditary multiple exostoses in a Chinese pedigree.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>The mutation IVS2+1G>A is the disease-causing mutation in the Chinese pedigree with hereditary multiple exostoses.</p>