PubMed Health⌕ Search

Biomedical subjects

M Claustres

Publications and source records attributed to M Claustres.

At least 55 records · Page 3Linked to original sources
PubMed1998

Mutation analysis of the dystrophin gene in Southern French DMD or BMD families: from Southern blot to protein truncation test.

Data from 6 years of experience in molecular diagnosis of Duchenne (DMD) and Becker (BMD) muscular dystrophy in Southern France are reported. DMD and BMD patients have been extensively analyzed for deletions and for point mutations in the dystrophin gene. By scanning the whole coding sequence as reverse-transcribed from lymphocytes or muscular RNA by the protein truncation test, we have reached a minimum of an 86% detection rate for point mutations responsible for DMD; these mutations consist of nonsense, frameshifting, and splicing mutations. Four of 12 small alterations identified in our sample are novel and described in this study. We also present an improved protocol for the automated detection of fluorescently labeled duplex polymerase chain reactions of six known intragenic microsatellites (Dys II, TG 15, STRs 44, 45, 49, and 50). Accurate sizing of the alleles at each locus was performed, and we elucidated the sequence of several repeat units. Allele frequencies at each of the six microsatellite loci and at one restriction fragment length polymorphism site (intron 16/TaqI) were defined in a sample of normal, DMD, and BMD X chromosomes from Southern France. The determination of the grandparental origin of either deletions or point mutations revealed differences depending on the type of the mutation, with most of the deletions occurring in oogenesis and most of the point mutations occurring in spermatogenesis.

Blotting, Southern↗
PubMed1998

Refinement of genetic localization of the Alström syndrome on chromosome 2p12-13 by linkage analysis in a North African family.

Alström syndrome is a rare autosomal recessive disorder characterized by retinal pigment degeneration, neurogenic deafness, infantile obesity, hyperlipidemia, and non-insulin-dependent diabetes mellitus. While the disease-related gene remains unknown, studies of the genetic isolate of French Acadians provisionally locate the Alström syndrome on chromosome 2p12-13 within a 14.9-cM interval. To confirm this finding in another ethnic population and refine the candidate region we investigated by linkage analysis a consanguineous family of North African origin, in which three of seven siblings displayed all major neurological and metabolic features of Alström syndrome. Genotyping was performed on an ABI377 DNA automatic sequencer and LOD scores were obtained with the Fastlink program. Five markers previously investigated in French Acadians confirmed the involvement of the candidate region, although pairwise LOD scores were of poor significance (Zmax = 2.9). To further confirm homogeneity and refine the candidate region, 20 additional markers were investigated. Haplotype analysis and allele segregation revealed that affected children shared a single haplotype and were homozygous for the eight most centromeric markers (D2S291-D2S2114), over a 6.1-cM interval. Significative multipoint LOD scores (Zmax = 3.96) were obtained between markers D2S2110/145 and D2S286. Two clusters of known genes are present in this refined region of chromosome 2p, the most attractive candidate being the hexokinase II gene. However, except for several known polymorphisms, no mutations were detected in the coding region of this gene. In conclusion, the location of Alström syndrome on chromosome 2p12-13 is confirmed, reducing the genetic interval to 6.1 cM.

Abnormalities, Multiple↗
PubMed1998

Dating the origin of the CCR5-Delta32 AIDS-resistance allele by the coalescence of haplotypes.

The CCR5-Delta32 deletion obliterates the CCR5 chemokine and the human immunodeficiency virus (HIV)-1 coreceptor on lymphoid cells, leading to strong resistance against HIV-1 infection and AIDS. A genotype survey of 4,166 individuals revealed a cline of CCR5-Delta32 allele frequencies of 0%-14% across Eurasia, whereas the variant is absent among native African, American Indian, and East Asian ethnic groups. Haplotype analysis of 192 Caucasian chromosomes revealed strong linkage disequilibrium between CCR5 and two microsatellite loci. By use of coalescence theory to interpret modern haplotype genealogy, we estimate the origin of the CCR5-Delta32-containing ancestral haplotype to be approximately 700 years ago, with an estimated range of 275-1,875 years. The geographic cline of CCR5-Delta32 frequencies and its recent emergence are consistent with a historic strong selective event (e.g. , an epidemic of a pathogen that, like HIV-1, utilizes CCR5), driving its frequency upward in ancestral Caucasian populations.

Acquired Immunodeficiency Syndrome↗
PubMed1998

The deltaccr5 mutation conferring protection against HIV-1 in Caucasian populations has a single and recent origin in Northeastern Europe.

The chemokine receptor CCR5 is encoded by the CMKBR5 gene located on the p21.3 region of human chromosome 3, and constitutes the major co-receptor for the macrophage-tropic strains of HIV-1. A mutant allele of the CCR5 gene, Delta ccr5 , was shown to provide to homozygotes with a strong resistance against infection by HIV. The frequency of the Delta ccr5 allele was investigated in 18 European populations. A North to South gradient was found, with the highest allele frequencies in Finnish and Mordvinian populations (16%), and the lowest in Sardinia (4%). Highly polymorphic microsatellites (IRI3.1, D3S4579 and IRI3.2, D3S4580 ) located respectively 11 kb upstream and 68 kb downstream of the CCR5 gene deletion were used to determine the haplotype of the chromosomes carrying the Delta ccr5 variant. A strong linkage disequilibrium was found between Delta ccr5 and specific alleles of the IRI3.1 and IRI3.2 microsatellites: >95% of the Delta ccr5 chromosomes carried the IRI3.1-0 allele, while 88% carried the IRI3.2-0 allele. These alleles were found respectively in only 2 or 1.5% of the chromosomes carrying a wild-type CCR5 gene. From these data, it was inferred that most, if not all Delta ccr5 alleles originate from a single mutation event, and that this mutation event probably took place a few thousand years ago in Northeastern Europe. The high frequency of the Delta ccr5 allele in Caucasian populations cannot be explained easily by random genetic drift, suggesting that a selection advantage is or has been associated with homo- or heterozygous carriers of the Delta ccr5 allele.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Linkage disequilibrium between the M470V variant and the IVS8 polyT alleles of the CFTR gene in CBAVD.

Congenital bilateral absence of the vas deferens (CBAVD) is a cause of male sterility mostly resulting from mutations in the cystic fibrosis transmembrane regulator (CFTR) gene. The most common defect is the 5T variant at the branch/acceptor site of intron 8, which induces high levels of exon 9 skipping leading to non-functional protein. However, this 5T variant has incomplete penetrance and variable expressivity, suggesting that some other regulatory factors may modulate the splicing of exon 9. To identify such factors, we report here the genetic analysis of a polymorphic locus, M470V, located in exon 10 of the CFTR gene in 60 patients with CBAVD, compared to a normal control population. The statistical analysis showed strong linkage disequilibrium between the 5T allele and the V allele of the M470V polymorphism in the CBAVD population, but not in the normal population. The V allele in a gene carrying 5T could, however, contribute to lowering the level of normal transcripts, as already suggested by in vitro transcriptional studies. These genetic findings, together with previous studies, suggest involvement of the M470V variant in the modulation of the splicing of exon 9 of the CFTR gene.

Alleles↗
PubMed1998

Altered rep-1 expression due to substitution at position +3 of the IVS13 splice-donor site of the choroideremia (CHM) gene.

PURPOSE: To characterize the effect on mRNA splicing of a yet undescribed mutation located in intron 13 splice-donor sequence (IVS13 + 3A --> C) in the Rab-Escort-protein 1 gene of a patient with choroideremia. METHODS: The base substitution was firstly detected by the Single Strand conformation analysis from genomic DNA. A REP-1 cDNA region encompassing exons 10-14 was then specifically amplified from lymphocytes-derived mRNA. RESULTS: We could demonstrate that this substitution affects REP-1 RNA processing. The patient revealed only one aberrantly spliced mRNA lacking exon 13 and no normal transcript. CONCLUSION: The skipping of exon 13 results in the creation of a stop codon at the misspliced junction. This is the first case of nucleotide substitution at the +3 position of a splice donor site so far described in choroideremia.

Adaptor Proteins, Signal Transducing↗
PubMed1998

[Clinical features and genetic analysis in a family with X-linked incomplete congenital stationary night blindness (CSNBi)].

PURPOSE: We describe particular clinical features in a three-generation family with X-linked CSNBi and present the genetic analysis. METHOD: The diagnosis of CSNBi was established on clinical and electrophysiological criteria. Polymorphic DNA markers of the Xp region were analyzed by fluorescent polymerase chain reaction. RESULTS: Clinical findings evidenced an atypical association of both myopia and hyperopia in the same brotherhood. The most interesting feature in this family was the observation of major worsening of the clinical shape between the first and the third generation of affected individuals. DNA analysis did not show significant linkage between the disease and markers of the Xp11-p21 region. Southern analysis did not show expansion of trinucleotide repeat CAG/CTG and CCG/CGG over the three generation. CONCLUSION: Haplotypic analysis together with clinical observations allow to exclude the existence of a myopia gene closely linked to the CSNB2 locus. The clinical anticipation observed in this family does not seem to be linked with trinucleotide repeat expansion CAG/CTG or CCG/CGG.

Adolescent↗
PubMed1998

[Update on a diagnostic test for choroideremia: the protein truncation test (PTT)].

PURPOSE: The aim of this study was to define the RT-PCR-PTT parameters for CHM gene analysis and to evaluate its interest as a method for CHM mutation screening. METHODS: The entire CHM coding region was reversed-transcribed in three overlapping cDNA segments (RT-PCR) which were amplified and further analyzed by PTT after in vitro transcription/translation. RESULTS: This strategy enabled us to detect a truncated peptide in each of the 6 unrelated patients from southern France who were investigated. The mutation was further characterized by direct sequencing of the RT-PCR product. CONCLUSION: In CHM gene, all conditions are present to make the RT-PCR-PTT strategy the method of choice for mutation screening. As a result of the simplified protocol described in this study, the families of the patients could benefit from accurate carrier-status assessment.

Adaptor Proteins, Signal Transducing↗
PubMed1997

SSCP analysis: a blind sensitivity trial.

Studies of the sensitivity of SSCP analysis usually have been performed under conditions contrary to the rules of quality control trials and have produced widely different results. We have performed a blind trial of the sensitivity of SSCP analysis for the detection of mutations in fragments up to 500 bp in length under a fixed single set of electrophoretic conditions. The mutation detection rate was 84%. In addition, we have identified a second mutation in nine samples. All these mutations are polymorphisms, including a novel polymorphism 1248 + 52T/C first reported in the present work.

Cystic Fibrosis Transmembrane Conductance Regulato↗
PubMed1997

The protein truncation test (PTT) as a method of detection for choroideremia mutations.

The predominance of truncative mutations responsible for choroideremia (CHM) led us to investigate the use of the protein truncation test (PTT) applied to lymphocyte RNA derived from affected males as a scanning method. The entire CHM coding region was reversed-transcribed in three overlapping cDNA segments (RT-PCR) which were amplified and further analysed by PTT after in vitro transcription/ translation. This strategy enabled us to detect the CHM-causative alteration in each of the four unrelated patients from southern France who were investigated. We describe three novel mutations (E177X, 323delT, 1313delTC), and report one recurrent mutation (R267X) in CHM. We believe this to be the first attempt at applying RT-PCR-PTT to CHM mutation detection.

Choroideremia↗
PubMed1997

Lack of evidence for connexin 43 gene mutations in human autosomal recessive lateralization defects.

Heterotaxy is the failure of the developing embryo to establish normal left-right asymmetry, which is often associated with multiple malformations. Previous studies have identified different mutations in the cytoplasmic tail of the connexin 43 (cx 43) gene in six patients from a series of six sporadic cases with defects of laterality and severe heart malformations. These cases showed that of the genes involved in lateralization defects with autosomal recessive transmission, cx 43 was the most important. This result was challenged by two different teams, which, on sequencing only the carboxyl terminal end of the cx 43 gene in 30 patients, found no mutations. To assess the responsibility of the cx 43 gene in human autosomal recessive lateralization defects, we tested its involvement in a selected group of 25 patients (19 familial cases) with a wide variety of lateralization defects and cardiovascular malformations. The whole coding sequence and direct flanking sequences were screened for mutations, both by single strand conformation analysis and direct fluorescent sequencing. We could only detect a single base pair insertion in the 3' untranslated region of one patient. To test the possibility of mutations in other parts of the cx 43 gene, the gene was located onto the physical map of chromosome 6, and flanking polymorphic markers were genotyped. Haplotype analysis excluded the cx 43 gene locus in nearly all of the familial cases of lateralization defects. Thus, our results do not support the suggestion that this gene is implicated in human autosomal recessive lateralization defects.

Abnormalities, Multiple↗
PubMed1997

Cystic fibrosis in Lebanon: distribution of CFTR mutations among Arab communities.

Cystic fibrosis (CF) is thought to be rare among the Arab populations from the Middle East and little data have been reported so far. We have studied a sample of 20 families living in Lebanon for several generations and who have at least one child with CF. These families are mainly from the Maronite, Greek Catholic, Greek Orthodox. Shiite or Sunnite groups. We found a 50% rate of consanguineous marriage, independent of the community of origin. The distribution of CF genotypes was determined through the screening of all exons of the CFTR (cystic fibrosis transmembrane conductance regulator) gene by the technique of denaturing gradient gel electrophoresis combined with asymmetric amplification DNA sequencing. A total of ten different mutations accounting for 87.5% of 32 unrelated CF alleles was identified, including two novel putative mutations (E672del and IVS21-28G-->A). Three mutations, delta F508 (37.5%), W1282X (15.6%), and N1303K (9.4%) accounted for 62.5% of CF alleles. Interestingly, in the Maronite group, 66.7% of the delta F508 chromosomes were found to be associated with allele 7 of the IVS8(T)tract, contrasting with the absolute linkage disequilibrium between European delta F508 chromosomes and allele 9. During this study, two previously undescribed polymorphisms (IVS14a + 17del5 and 2691T/C) were also identified.

Arabs↗
PubMed1997

Recurrent PIG-A mutation (IVS5+1G-->A) in a paediatric case of paroxysmal nocturnal haemoglobinuria: detection by the protein truncation test.

Paroxysmal nocturnal haemoglobinuria (PNH) is an acquired haemopoietic stem cell disorder caused by the absence of glycosyl phosphatidylinositol (GPI)-anchored surface proteins due to a deficient biosynthesis of GPI-anchor. The disease occurs predominantly in adults, and very few cases have been described in children and adolescents. Recent analyses have shown that null mutations in the X-linked PIG-A (phosphatidylinositol glycan-class A) gene are responsible for GPI-anchor deficiency in most PNH adult patients analysed. We report a young male from southern France who was diagnosed with PNH at 12 years of age during follow-up of aplastic anaemia. To further elucidate the molecular basis of PNH occurring in childhood, we used the powerful and rapid protein truncation test to scan for truncative mutations in the entire PIG-A mRNA reverse transcribed and amplified from blood mononuclear cells. The somatic defect responsible for PNH in the patient was found to be a splicing mutation. IVS5+1G-->A, which has previously been described in two Asiatic adults with PNH.

Child↗