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B Grandchamp

Publications and source records attributed to B Grandchamp.

At least 91 records · Page 5Linked to original sources
PubMed1994

Localization of the human coproporphyrinogen oxidase gene to chromosome band 3q12.

The human gene encoding coproporphyrinogen oxidase is the defective gene in hereditary coproporphyria. This gene was mapped to chromosome band 3q12 using fluorescent in situ hybridization. The chromosomal localization was confirmed by cosegregation of the human gene with chromosome 3 in a panel of human/rodent somatic hybrids.

Animals↗
PubMed1994

Detection of eleven mutations causing acute intermittent porphyria using denaturing gradient gel electrophoresis.

Acute intermittent porphyria (AIP) is an autosomal dominant disease characterized by mutations of the gene coding for porphobilinogen deaminase (PBGD). Until now, sixteen different mutations have been described. In an effort to investigate further the molecular epidemiology of AIP, we have undertaken a systematic study of different exons of the PBGD gene from a large number of unrelated patients. Here, we have examined seven of the fifteen exons of the gene from 43 unrelated Dutch and French AIP patients using denaturing gradient gel electrophoresis after polymerase chain reaction amplification. Eleven new mutations were found, accounting for the enzymatic defect in about half of the patients. This study further documents the molecular heterogeneity of the mutations responsible for AIP and describes an efficient strategy to detect the mutations in patients with previously unknown abnormalities.

Base Sequence↗
PubMed1994

Homozygous hereditary coproporphyria caused by an arginine to tryptophane substitution in coproporphyrinogen oxidase and common intragenic polymorphisms.

Coproporphyrinogen oxidase is a mitochondrial heme-biosynthetic enzyme that converts coproporphyrinogen to protoporphyrinogen. Inherited deficiency of this enzyme causes the human genetic disease hereditary coproporphyria. Recently, we isolated, sequenced and expressed the cDNA encoding human coproporphyrinogen oxidase. This allowed us to investigate the nature of the defect leading to a profound deficiency of coproporphyrinogen oxidase in a patient with homozygous hereditary coproporphyria. Using reverse-transcription, amplification of the cDNA and direct sequencing of the amplified products, we found a point mutation resulted in an arginine to tryptophane substitution (R231W). Expression studies of normal and mutated cDNAs in a bacterial system demonstrated that this substitution resulted in the synthesis of an unstable protein with a residual catalytic activity. This is the first mutation to be found at the coproporphyrinogen oxidase locus. Furthermore, three common polymorphisms within the coproporphyrinogen oxidase gene were detected. Two DNA polymorphisms resulted in amino acids changes (H172N and V194I) and the third one was silent (E230E).

Amino Acid Sequence↗
PubMed1994

Coproporphyrinogen oxidase: gene organization and description of a mutation leading to exon 6 skipping.

Genomic clones containing a human coproporphyrinogen oxidase gene, were isolated. DNA sequencing indicates that the human CPX gene spans about 14 kb and consists of seven exons and six introns. Sequences were determined for all the exons, exon-intron junctions and for 800 bp of promoter region. Introns vary in size from 269 bp to 5 kb and they all have consensus sequences at their boundaries. Primer extension and ribonuclease protection experiments revealed multiple transcriptional initiation sites in a region with sequence motifs characteristic of a promoter. The promoter region is GC-rich and contains multiple potential Sp 1 elements, CACCC boxes and potential GATA-1 binding sites. The availability of the CPX genomic sequence allowed us to determine the mutation in a patient with a hereditary coproporphyria. AG to A mutation was found at the last position of exon 6. This mutation results in exon skipping.

Amino Acid Sequence↗
PubMed1994

[New tumor suppressor genes intervening in the regulation of the cycle].

Eukaryotic cell cycle progression is governed by multiple cyclin and cyclin-dependent kinases interactions that are in turn regulated by multiple factors. Recently, inhibitors of cyclin/cyclin-dependent kinases activities have been characterized and their genes have been cloned. Alterations of some these genes may play a major in tumor initiation or progression.

Cell Cycle↗
PubMed1993

Ferrochelatase structural mutant (Fechm1Pas) in the house mouse.

The molecular basis of an inherited defect of ferrochelatase in mouse (Fechm1Pas/Fechm1Pas, described by Tutois et al., 1991, J. Clin. Invest. 88:1730-1736) was investigated. cDNA clones encoding ferrochelatase, isolated by amplification of the mRNA from the liver of a mutant mouse using the polymerase chain reaction, were sequenced by the dideoxynucleotide chain-termination method. All the clones carried a T to A transversion at nucleotide 293, leading to a methionine to lysine substitution at position 98 in the protein (mutation M98K). Hybridization with allele-specific oligonucleotides (ASOs) confirmed the mutation at the cDNA and genomic levels. Finally, expression of the mutant ferrochelatase protein in E. coli demonstrated a marked deficiency in activity in agreement with the activity of the deficient enzyme in vivo. This Fechm1Pas/Fechm1Pas mutant mouse represents a useful model for studying the pathophysiological feature of the human disease and the first accessible model for gene therapy in the field of porphyrias.

Animals↗
PubMed1993

High prevalence of a point mutation in the porphobilinogen deaminase gene in Dutch patients with acute intermittent porphyria.

Acute intermittent porphyria (AIP) is an autosomal dominant disease characterized by a deficiency of porphobilinogen deaminase (PBGD). Up to now 14 different mutations have been described. In an effort to investigate the molecular epidemiology of AIP we have undertaken a systematic study of different exons of the PBGD gene from a large number of unrelated patients. Here, exon 8 from 82 unrelated Dutch and French AIP patients was examined using single strand confirmation polymorphism analysis (SSCP) after polymerase chain reaction (PCR) amplification. A single base mutation, C to T, at position 346 of the sequence coding for PBGD was observed in 15 Dutch families but in only 1 French family. A simple PCR assay is described to facilitate the diagnosis of this common mutation at the DNA level.

Base Sequence↗
PubMed1993

Association between genetic variation at the porphobilinogen deaminase gene and schizophrenia.

There is growing evidence that some genetic predisposition is important in the etiology of schizophrenia. We have sought to implicate a major gene by performing a candidate gene association study comparing the allele frequencies of seven restriction fragment length polymorphisms (RFLPs) at six loci in both a psychiatrically normal control group (N = 51) and an affected (schizophrenia or schizoaffective disorder) group (N = 55). Each group comprised Caucasians of northern European origin. The candidate areas (D5S39, D5S78, dopamine receptor D2 (DRD2), D11S29, porphobilinogen deaminase (PBGD), and D11S84) were selected on the basis of prior cytogenetic findings in schizophrenics, linkage studies, and/or implicated gene products. The presence of a polymorphic ApaLI site within the PBGD gene showed a significant association with the presence of illness (P = 0.02). The relative risk of possessing the allele with the ApaLI site was 2.10. No significant association was found with any of the six other RFLPs. Our data suggests that either the PBGD gene itself or an unknown gene linked to and/or in linkage disequilibrium with the PBGD locus predisposes some individuals to schizophrenia. Independent replication of these findings will be required to determine their relevance to schizophrenia.

Adolescent↗
PubMed1992

Restricted diversity of V gamma 9-JP rearrangements in unstimulated human gamma/delta T lymphocytes.

The diversity of human peripheral blood gamma/delta T cells is known to be limited by the preferential use of V genes coding for V gamma 9 (usually linked to JP) and V delta 2. We show that the diversity of these cells is further limited at the junctional region. First, an identical rearrangement is found in 10%-30% of all gamma/delta T cells which contain V gamma 9-JP rearrangements. Second, the vast majority of V gamma 9-JP rearrangements which are different from this predominant sequence have, nevertheless, the same length or code for variable regions whose length differs by only one amino acid (+/- 1). Overall, 30%-50% of V gamma 9-JP rearrangements have a junctional region which encodes for a peptide with the amino acid sequence E VX EL, in which EV is predominantly, but not exclusively, encoded by the germ-line V gamma 9 sequence and EL is encoded by JP. The X amino acid is variable, but a glutamine is over-represented. The diversity of the V gamma 9-JP repertoire is fairly constant in different individuals and at different ages, including before, during and after the post-natal expansion of peripheral blood gamma/delta T cells.

Adult↗
PubMed1992

Heterogeneity of mutations in the uroporphyrinogen III synthase gene in congenital erythropoietic porphyria.

Congenital erythropoietic porphyria (CEP) or Günther's disease is an inborn error of heme biosynthesis transmitted as an autosomal recessive trait and characterized by a profound deficiency of uroporphyrinogen III synthase (UROIIIS) activity. We have previously described two missense mutations in the UROIIIS gene, confirming that the primary defect responsible for CEP is a structural alteration of this gene. We have extended our work to 5 additional unrelated families. Two new point mutations, a deletion and an insertion have been found in the messenger RNA. Our study shows that a molecular heterogeneity of the mutations exists in Günther's disease. One mutation (C73R), however, appears to be more frequent than the others. Finally, the different normal and mutated proteins have been expressed in Escherichia coli to determine the consequence of the mutations on the enzyme activity.

Amino Acid Sequence↗
PubMed1992

Characterization of a new mutation (R292G) and a deletion at the human uroporphyrinogen decarboxylase locus in two patients with hepatoerythropoietic porphyria.

A deficiency in the activity of uroporphyrinogen decarboxylase (UROD), the fifth enzyme of the haem biosynthetic pathway, is found in familial porphyria cutanea tarda (F-PCT) and hepatoerythropoietic porphyria (HEP). A new mutation (R292G) and a deletion have been found in a pedigree with two HEP patients (two sisters). The R292G mutation was not detected in 13 unrelated affected patients with F-PCT, so it appears to be uncommon. The possibility that the arginine 292 may participate at the active site of the enzyme is discussed. A summary of the 7 mutations/deletions found in the UROD gene with their frequency is presented.

Amino Acid Sequence↗
PubMed1992

A second ferritin L subunit is encoded by an intronless gene in the mouse.

Multiple homologous sequences for the ferritin L subunit are present in mammalian genomes, but so far, only one expressed gene has been described. Here we report the isolation of a cDNA from a mouse bone marrow library, corresponding to an isoform of the mouse ferritin L subunit. This new subunit, that we named Lg, differs from the L subunit of ten amino acids. Specific amplification of mouse genomic DNA using the polymerase chain reaction (PCR) confirmed the presence of this Lg sequence in the mouse genome but also suggested that it must be encoded by an intronless gene. Using a series of different Lg-specific oligonucleotides as probes, we subsequently isolated a genomic clone containing an uninterrupted sequence, identical to the Lg cDNA. This Lg gene lacks introns and does not contain the 28 base pairs (bp) conserved motif usually present at the 5' end of most ferritin mRNAs, which confers translational regulation by iron. When transiently transfected into K562 cells, this Lg genomic clone is actively transcribed, suggesting that, although it possesses the characteristics of a processed pseudogene, it is likely to correspond to the gene encoding this new ferritin subunit.

Amino Acid Sequence↗
PubMed1992

Quantitative determination of the hybrid Bcr-Abl RNA in patients with chronic myelogenous leukaemia under interferon therapy.

In vitro amplification of the Bcr-Abl cDNA has been widely used to assess for the presence of minimal residual disease in patients with chronic myelogenous leukaemia (CML) presenting with complete clinical and cytogenetic remission. However, the level of sensitivity achieved in different laboratories remains largely unknown. Moreover, the results are usually expressed as positive or negative, making a precise follow-up of the patients difficult. In an attempt to overcome these limitations, we devised a quantitative method to measure the amount of Bcr-Abl mRNA in clinical samples. This methodology involves a single reverse transcription step, followed by separate amplifications of Bcr-Abl and total Abl mRNA. These two amplifications are performed in the presence of different dilutions of a same internal standard. This standard consists of Bcr-Abl sequences with an eight bases deletion in exon 2 of Abl. One of the primers used in each separate reaction is labelled with fluorescein. Following amplification, PCR products derived from cellular RNA and those from the internal standard are separated and their relative fluorescence is determined using a laser fluorescent DNA sequencer (ALF, Pharmacia). The number of Bcr-Abl and total Abl mRNA molecules initially present in each sample is then calculated. The accuracy and reproducibility of this method was assessed by studying serial dilutions of K562 RNA into normal RNA. Blood samples from 10 patients in cytogenetic remission under interferon therapy were studied. Only one sample was found negative while the others contained between 0.05 and 17 hybrid Bcr-Abl mRNA molecules per 1000 molecules of Abl mRNA. These results suggest that a variable number of malignant cells are present in the majority of CML patients in cytogenetic remission following interferon therapy.

Adult↗