Mutator phenotypes have been described in laboratory-evolved bacteria, as well as in natural isol... more Mutator phenotypes have been described in laboratory-evolved bacteria, as well as in natural isolates. Several genes can be impacted, each of them being associated with a typical mutational spectrum. By studying one of the oldest strains available, the ancestral Escherich strain, we were able to identify its mutator status leading to tremendous genetic diversity among the isolates from various collections and allowing us to reconstruct the phylogeographic history of the strain. This mutator phenotype was probably acquired during the storage of the strain, promoting adaptation to a specific environment. Other mutations in rpoS and efflux pump- and porin-encoding genes highlight the acclimatization of the strain through self-preservation and nutritional competence regulation. This strain history can be viewed as unintentional experimental evolution in culture collections all over the word since 1885, mimicking the long-term experimental evolution of E. coli of Lenski et al. (O. Tenail...
Introduction et objectifs-La pyélonéphrite aiguë (PNA) est une pathologie fréquente d'évolution s... more Introduction et objectifs-La pyélonéphrite aiguë (PNA) est une pathologie fréquente d'évolution souvent favorable parfois récidivante. Nous avons analysé les facteurs d'échec des PNA communautaires de l'adulte. Matériels et méthodes-Étude rétrospective (1990-2000) englobant les adultes hospitalisés pour PNA communautaire. L'échec est défini par la récidive de l'infection urinaire quel que soit son type, son délai et le germe responsable. La PNA est compliquée en cas de sexe masculin, diabète, anomalies des voies urinaires, rein unique, immunodépression, femmes = 65 ans. Résultats-224 malades sont inclus : 46 hommes (20,5 %) et 178 femmes (79,5 %) dont 58 ménopausées (32,6 %). Ils ont été régulièrement suivis après la sortie (délai moyen : 15 semaines). 14,7 % sont diabétiques, 21,9 % ont une anomalie des voies urinaires. La PNA est compliquée dans 107 cas (47,8 %). Le germe prédominant est Escherichia coli (82 %). La durée moyenne de l'antibiothérapie est de 15,5 j. 82,5 % des cas sont traités par voie parentérale, 7,5 % par une bithérapie et 13 % au-delà de 21 j. L'ECBU de fin de traitement est négatif dans tous les cas. Un échec est noté dans 66 cas (29,5 %) : 57 femmes et 9 hommes. Le tableau clinique est celui d'une PNA dans 30 cas (45 %). Le caractère compliqué de la PNA, la durée du traitement, la voie d'administration des antibiotiques et le recours à la monothérapie versus bithérapie, ne sont pas corrélés à la survenue d'échec des PNA. Seuls la ménopause (p = 0,04) et la présence d'une infection vulvo-vaginale (p = 0,005) sont significativement corrélés à la survenue d'un échec. Conclusion-Dans notre travail, les facteurs d'échec de la PNA sont la présence d'une infection vaginale et la ménopause. Par conséquent, un foyer infectieux gynécologique associé doit être systématiquement recherché et traité ainsi que la pratique régulière de l'ECBU chez la femme ménopausée. COL6-02 Facteurs prédictifs de gravité des bactériémies à Escherichia coli (BEc) : étude COLIBAFI
Comptes rendus des séances de la Société de biologie et de ses filiales, 1994
Spinal muscular atrophies (SMA) represent the second most common fatal autosomal recessive disord... more Spinal muscular atrophies (SMA) represent the second most common fatal autosomal recessive disorder after cystic fibrosis. Childhood SMAs are divided into severe (type I) and mild forms (types II and III). By a combination of genetic and physical mapping, a YAC contig of the 5q13 region spanning the disease locus was constructed that showed the presence of low copy-repeats in this region. Allele segregation was analyzed at the closest genetic loci detected by markers C212 and C272 in 201 SMA families. Inherited and de novo deletions were observed in 10 SMA patients. Moreover, deletions were strongly suggested in at least 18% of SMA type I patients by the observation of marked heterozygosity deficiency for the loci studied. These results indicate that deletion events are statistically associated with the severe form of SMA.
Spinal muscular atrophies (SMAs) represent the second most common fatal autosomal recessive disor... more Spinal muscular atrophies (SMAs) represent the second most common fatal autosomal recessive disorder after cystic fibrosis. Childhood spinal muscular atrophies are divided into severe (type I) and mild forms (types II and III). By a combination of genetic and physical mapping, a yeast artificial chromosome contig of the 5q13 region spanning the disease locus was constructed that showed the presence of low copy repeats in this region. Allele segregation was analyzed at the closest genetic loci detected by markers C212 and C272 in 201 SMA families. Inherited and de novo deletions were observed in nine unrelated SMA patients. Moreover, deletions were strongly suggested in at least 18 percent of SMA type I patients by the observation of marked heterozygosity deficiency for the loci studied. These results indicate that deletion events are statistically associated with the severe form of spinal muscular atrophy.
Although polymicrobial infections, caused by combinations of viruses, bacteria, fungi and parasit... more Although polymicrobial infections, caused by combinations of viruses, bacteria, fungi and parasites, are being recognised with increasing frequency, little is known about the occurrence of within-species diversity in bacterial infections and the molecular and evolutionary bases of this diversity. We used multiple approaches to study the genomic and phenotypic diversity among 226 Escherichia coli isolates from deep and closed visceral infections occurring in 19 patients. We observed genomic variability among isolates from the same site within 11 patients. This diversity was of two types, as patients were infected either by several distinct E. coli clones (4 patients) or by members of a single clone that exhibit micro-heterogeneity (11 patients); both types of diversity were present in 4 patients. A surprisingly wide continuum of antibiotic resistance, outer membrane permeability, growth rate, stress resistance, red dry and rough morphotype characteristics and virulence properties were present within the isolates of single clones in 8 of the 11 patients showing genomic micro-heterogeneity. Many of the observed phenotypic differences within clones affected the trade-off between self-preservation and nutritional competence (SPANC). We showed in 3 patients that this phenotypic variability was associated with distinct levels of RpoS in co-existing isolates. Genome mutational analysis and global proteomic comparisons in isolates from a patient revealed a star-like relationship of changes amongst clonally diverging isolates. A mathematical model demonstrated that multiple genotypes with distinct RpoS levels can co-exist as a result of the SPANC trade-off. In the cases involving infection by a single clone, we present several lines of evidence to suggest diversification during the infectious process rather than an infection by multiple isolates exhibiting a micro-heterogeneity. Our results suggest that bacteria are subject to trade-offs during an infectious process and that the observed diversity resembled results obtained in experimental evolution studies. Whatever the mechanisms leading to diversity, our results have strong medical implications in terms of the need for more extensive isolate testing before deciding on antibiotic therapies.
Escherichia coli SOS functions constitute a multifaceted response to DNA damage. We undertook to ... more Escherichia coli SOS functions constitute a multifaceted response to DNA damage. We undertook to study the role of yafP, a SOS gene with unknown function. yafP is part of an operon also containing the dinB gene coding for DNA Polymerase IV (PolIV). Our phylogenetic analysis showed that the gene content of this operon is variable but that the dinB and the yafP genes are conserved in the majority of E. coli natural isolates. Therefore, we studied if these proteins are functionally linked. Using a murine septicaemia model, we showed that YafP activity reduced the bacterial fitness in the absence of PolIV. Similarly, YafP increased cytotoxicity of two DNA damaging nitroaromatic compounds, 4-nitroquinoline-1-oxide (NQO) and nitrofurazone, in the absence of PolIV. The fact that PolIV counterbalances YafP-induced cytotoxicity could explain why these two genes are transcriptionally linked. We also studied the involvement of YafP in genotoxic-stress induced mutagenesis and found that PolIV and YafP reduced NQO-induced mutagenicity. The YafP antimutator activity was independent of the PolIV activity. Given that YafP was annotated as a putative acetyltransferase, it could be that YafP participates in the metabolic transformation of genotoxic compounds, hence modulating the balance between their mutagenicity and cytotoxicity.
Neural networks SIR—Baxt's review of the clinical application of neural network methods (Oc... more Neural networks SIR—Baxt's review of the clinical application of neural network methods (Oct 28, p 1135) suggested benefits over standard techniques for the analysis of pathophysiological processes. In respect of cancer outcome prediction we suggest that the validity of this conclusion is uncertain because the studies Baxt cites do not include statistical tests of the significance of the results. Our review of how such results might be formally tested yields two important general principles, illustrated by considering the studies Baxt cites.
Spinal muscular atrophy (SMA) is characterised by degeneration of anterior horn cells of the spin... more Spinal muscular atrophy (SMA) is characterised by degeneration of anterior horn cells of the spinal cord and represents the second most common, lethal, autosomal recessive disorder after cystic fibrosis. Based on the criteria of the Internatinal SMA Consortium, childhood SMAs are classified into type I (Werdnig-Hoffmann disease), type II (intermediate form), and type III (Kugelberg-Welander disease).
The spinal form of Charcot-Marie-Tooth disease (spinal CMT) is a rare genetic disorder of the per... more The spinal form of Charcot-Marie-Tooth disease (spinal CMT) is a rare genetic disorder of the peripheral nervous system, the genetic basis of which remains unknown. To test the hypothesis that a defect of survival motor neuron (SMN), the determining gene for spinal muscular atrophy (SMA), would result in spinal CMT, 18 unrelated spinal CMT patients were studied. Nine of them were sporadic cases and the other nine belonged to unrelated autosomal dominant pedigrees. None of the 18 patients showed deletions involving SMN exons 7 or 8, the most frequent gene alteration found in SMA. In addition, haplotype analysis in two large autosomal dominant pedigrees showed that the 5q13 locus was not segregating with the spinal CMT locus. Therefore, neither the sporadic nor the familial cases of spinal CMT are associated with a SMN gene deletion, nor are the familial cases linked to the 5q13 region, indicating that this neuropathy is genetically different from SMA.
We report on a 38-day-old infant who developed pleuropneumonia due to a Staphylococcus aureus str... more We report on a 38-day-old infant who developed pleuropneumonia due to a Staphylococcus aureus strain responsible for familial furunculosis, which was acquired by maternal breast-feeding. All isolates from the infant and parents were genetically related by randomly amplified polymorphic DNA analysis and produced Panton-Valentine leukocidin.
An anonymous 14.9-kb rrn -containing HindIII fragment is strongly linked to Escherichia coli stra... more An anonymous 14.9-kb rrn -containing HindIII fragment is strongly linked to Escherichia coli strains causing neonatal meningitis. We show in this report that this fragment does not encode new virulence factors but lacks arpA , a gene common in avirulent E. coli strains, and we developed a PCR test to detect this fragment.
The survival motor neuron (SMN) gene was lacking in 6/12 patients with arthrogryposis multiplex c... more The survival motor neuron (SMN) gene was lacking in 6/12 patients with arthrogryposis multiplex congenita (AMC) associated with spinal muscular atrophy (SMA). Neither point mutation in the SMN gene nor evidence for linkage to chromosome 5q13 were found in the other patients. Hitherto, arthrogryposis was regarded as an exclusion criterion in SMA. Our data strongly suggest that AMC of neurogenic origin is genetically heterogeneous, with a subgroup being allelic to SMA. Absence or interruption of the SMN gene in the AMC-SMA association will make the diagnosis easier and genetic counselling will now become feasible.
In their molecular epidemiological analysis of Escherichia coli urosepsis isolates, Bingen-Bidois... more In their molecular epidemiological analysis of Escherichia coli urosepsis isolates, Bingen-Bidois et al. interpret the finding of a pathogenicity island (PAI) II J96-like domain in multiple ribotypes as conflicting with previous reports, which ostensibly describe this element as being confined to a single clone (1). This is potentially misleading, since the two references cited actually pertain to papG allele I, which is a hallmark of a different PAI from that of strain J96, i.e., PAI I. Indeed, papG allele I, which was absent from the population analyzed by Bingen-Bidois et al. (rather than being found in multiple ribotypes), is quite rare, having been found almost exclusively in strains closely related to strain J96 (4). In contrast, many previous reports have documented the co-occurrence of papG allele III, hly, and cnf1 (which implies the presence of a PAI II J96-like domain, as discussed by Bingen-Bidois et al.) in multiple group B2-derived lineages (3). These include clonal groups 1 and 2 of Cherifi et al. (2) (which equate, respectively, electrophoretic types [ETs] 1 and 21 of Whittam et al. [7] and ETs 47 and 42 of Maslow et al. [6], the latter clonal group including archetypal strain 536), the O2:K5/K7:H1 clonal group (ET 39 of Maslow et al.), and the O18:K1:H7 clonal group that includes archetypal strains RS218 (meningitis) and NU14 (cystitis) (3, 5).
Communicated by Sergio Ottolenghi Spinal muscular atrophy (SMA) is a common autosomal recessive d... more Communicated by Sergio Ottolenghi Spinal muscular atrophy (SMA) is a common autosomal recessive disease. SMA is linked to the 5q13 locus in 95% of patients, and in at least 98% of them, the SMN1 homozygous deletion is found. Compound heterozygous patients, who have an SMN1 deletion associated with a subtle mutation, appear undeleted with the common molecular diagnostic test that detects only the homozygous absence of SMN1. In these patients, mutation screening in SMN1 is hampered by the presence of several copies of the highly homologous SMN2 gene. Here, we present a rapid and reliable strategy for detecting SMN mutations using long-range PCR, which avoids cloning and cDNA analysis. Using this method, we found 10 mutations, including five mutations never reported previously and five recurrent mutations; some of them are probably population-specific. Marker analysis of the 5q13 locus in these mutations showed common haplotypes, supporting the hypothesis of a common ancestor rather than a hot spot sequence. We also evaluate the suitability of automated SSCA and DHPLC for mutation scanning. Hum Mutat 24:417-427, 2004.
Recently, a spinal muscular atrophy (SMA) determining gene, termed survival motor neuron (SMN) ge... more Recently, a spinal muscular atrophy (SMA) determining gene, termed survival motor neuron (SMN) gene, has been isolated from the 5q13 region and found deleted in most patients. A highly homologous copy of this gene has also been isolated and located in a centromeric position. We have analyzed 158 patients (SMA types I-IV) and found deletions of SMN exon 7 in 96.8%. Mutations other than gross deletions seem to be extremely rare. In one of the undeleted SMA type I patients, a newborn who survived for only 42 days, we detected a maternally inherited 5 bp microdeletion in exon 3, resulting in a premature stop codon. By RT-PCR and long range PCR amplification we were able to show that the deletion belongs to the SMN gene, rather than to the centromeric copy, and that the proposita had no paternal SMN gene. Analysis of the neuronal apoptosis inhibitor protein (NAIP) gene, which maps close to SMN and has been proposed as a SMA modifying gene, suggests the presence of at least one fulllength copy. Haplotype analysis of closely linked polymorphic markers suggests that the proposita also lacks the maternally derived copy of the centromeric homologue of SMN supporting the hypothesis that the severity of the phenotype might depend on the reduced number of centromeric genes in addition to the frameshift mutation.
Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder characterize... more Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder characterized by degeneration of motor neurons of the spinal cord and muscular atrophy. SMA is caused by alterations to the survival of motor neuron (SMN) gene, the function of which has hitherto been unclear. Here, we present immunoblot analyses showing that normal SMN protein expression undergoes a marked decay in the postnatal period compared with fetal development. Morphological and immunohistochemical analyses of the SMN protein in human fetal tissues showed a general distribution in the cytoplasm, except in muscle cells, where SMN protein was immunolocalized to large cytoplasmic dot-like structures and was tightly associated with membrane-free heavy sedimenting complexes. These cytoplasmic structures were similar in size to gem. The SMN protein was markedly deficient in tissues derived from type I SMA fetuses, including skeletal muscles and, as previously shown, spinal cord. While our data do not help decide whether SMA results from impaired SMN expression in spinal cord, skeletal muscle or both, they suggest a requirement for SMN protein during embryo-fetal development.
Mutator phenotypes have been described in laboratory-evolved bacteria, as well as in natural isol... more Mutator phenotypes have been described in laboratory-evolved bacteria, as well as in natural isolates. Several genes can be impacted, each of them being associated with a typical mutational spectrum. By studying one of the oldest strains available, the ancestral Escherich strain, we were able to identify its mutator status leading to tremendous genetic diversity among the isolates from various collections and allowing us to reconstruct the phylogeographic history of the strain. This mutator phenotype was probably acquired during the storage of the strain, promoting adaptation to a specific environment. Other mutations in rpoS and efflux pump- and porin-encoding genes highlight the acclimatization of the strain through self-preservation and nutritional competence regulation. This strain history can be viewed as unintentional experimental evolution in culture collections all over the word since 1885, mimicking the long-term experimental evolution of E. coli of Lenski et al. (O. Tenail...
Introduction et objectifs-La pyélonéphrite aiguë (PNA) est une pathologie fréquente d'évolution s... more Introduction et objectifs-La pyélonéphrite aiguë (PNA) est une pathologie fréquente d'évolution souvent favorable parfois récidivante. Nous avons analysé les facteurs d'échec des PNA communautaires de l'adulte. Matériels et méthodes-Étude rétrospective (1990-2000) englobant les adultes hospitalisés pour PNA communautaire. L'échec est défini par la récidive de l'infection urinaire quel que soit son type, son délai et le germe responsable. La PNA est compliquée en cas de sexe masculin, diabète, anomalies des voies urinaires, rein unique, immunodépression, femmes = 65 ans. Résultats-224 malades sont inclus : 46 hommes (20,5 %) et 178 femmes (79,5 %) dont 58 ménopausées (32,6 %). Ils ont été régulièrement suivis après la sortie (délai moyen : 15 semaines). 14,7 % sont diabétiques, 21,9 % ont une anomalie des voies urinaires. La PNA est compliquée dans 107 cas (47,8 %). Le germe prédominant est Escherichia coli (82 %). La durée moyenne de l'antibiothérapie est de 15,5 j. 82,5 % des cas sont traités par voie parentérale, 7,5 % par une bithérapie et 13 % au-delà de 21 j. L'ECBU de fin de traitement est négatif dans tous les cas. Un échec est noté dans 66 cas (29,5 %) : 57 femmes et 9 hommes. Le tableau clinique est celui d'une PNA dans 30 cas (45 %). Le caractère compliqué de la PNA, la durée du traitement, la voie d'administration des antibiotiques et le recours à la monothérapie versus bithérapie, ne sont pas corrélés à la survenue d'échec des PNA. Seuls la ménopause (p = 0,04) et la présence d'une infection vulvo-vaginale (p = 0,005) sont significativement corrélés à la survenue d'un échec. Conclusion-Dans notre travail, les facteurs d'échec de la PNA sont la présence d'une infection vaginale et la ménopause. Par conséquent, un foyer infectieux gynécologique associé doit être systématiquement recherché et traité ainsi que la pratique régulière de l'ECBU chez la femme ménopausée. COL6-02 Facteurs prédictifs de gravité des bactériémies à Escherichia coli (BEc) : étude COLIBAFI
Comptes rendus des séances de la Société de biologie et de ses filiales, 1994
Spinal muscular atrophies (SMA) represent the second most common fatal autosomal recessive disord... more Spinal muscular atrophies (SMA) represent the second most common fatal autosomal recessive disorder after cystic fibrosis. Childhood SMAs are divided into severe (type I) and mild forms (types II and III). By a combination of genetic and physical mapping, a YAC contig of the 5q13 region spanning the disease locus was constructed that showed the presence of low copy-repeats in this region. Allele segregation was analyzed at the closest genetic loci detected by markers C212 and C272 in 201 SMA families. Inherited and de novo deletions were observed in 10 SMA patients. Moreover, deletions were strongly suggested in at least 18% of SMA type I patients by the observation of marked heterozygosity deficiency for the loci studied. These results indicate that deletion events are statistically associated with the severe form of SMA.
Spinal muscular atrophies (SMAs) represent the second most common fatal autosomal recessive disor... more Spinal muscular atrophies (SMAs) represent the second most common fatal autosomal recessive disorder after cystic fibrosis. Childhood spinal muscular atrophies are divided into severe (type I) and mild forms (types II and III). By a combination of genetic and physical mapping, a yeast artificial chromosome contig of the 5q13 region spanning the disease locus was constructed that showed the presence of low copy repeats in this region. Allele segregation was analyzed at the closest genetic loci detected by markers C212 and C272 in 201 SMA families. Inherited and de novo deletions were observed in nine unrelated SMA patients. Moreover, deletions were strongly suggested in at least 18 percent of SMA type I patients by the observation of marked heterozygosity deficiency for the loci studied. These results indicate that deletion events are statistically associated with the severe form of spinal muscular atrophy.
Although polymicrobial infections, caused by combinations of viruses, bacteria, fungi and parasit... more Although polymicrobial infections, caused by combinations of viruses, bacteria, fungi and parasites, are being recognised with increasing frequency, little is known about the occurrence of within-species diversity in bacterial infections and the molecular and evolutionary bases of this diversity. We used multiple approaches to study the genomic and phenotypic diversity among 226 Escherichia coli isolates from deep and closed visceral infections occurring in 19 patients. We observed genomic variability among isolates from the same site within 11 patients. This diversity was of two types, as patients were infected either by several distinct E. coli clones (4 patients) or by members of a single clone that exhibit micro-heterogeneity (11 patients); both types of diversity were present in 4 patients. A surprisingly wide continuum of antibiotic resistance, outer membrane permeability, growth rate, stress resistance, red dry and rough morphotype characteristics and virulence properties were present within the isolates of single clones in 8 of the 11 patients showing genomic micro-heterogeneity. Many of the observed phenotypic differences within clones affected the trade-off between self-preservation and nutritional competence (SPANC). We showed in 3 patients that this phenotypic variability was associated with distinct levels of RpoS in co-existing isolates. Genome mutational analysis and global proteomic comparisons in isolates from a patient revealed a star-like relationship of changes amongst clonally diverging isolates. A mathematical model demonstrated that multiple genotypes with distinct RpoS levels can co-exist as a result of the SPANC trade-off. In the cases involving infection by a single clone, we present several lines of evidence to suggest diversification during the infectious process rather than an infection by multiple isolates exhibiting a micro-heterogeneity. Our results suggest that bacteria are subject to trade-offs during an infectious process and that the observed diversity resembled results obtained in experimental evolution studies. Whatever the mechanisms leading to diversity, our results have strong medical implications in terms of the need for more extensive isolate testing before deciding on antibiotic therapies.
Escherichia coli SOS functions constitute a multifaceted response to DNA damage. We undertook to ... more Escherichia coli SOS functions constitute a multifaceted response to DNA damage. We undertook to study the role of yafP, a SOS gene with unknown function. yafP is part of an operon also containing the dinB gene coding for DNA Polymerase IV (PolIV). Our phylogenetic analysis showed that the gene content of this operon is variable but that the dinB and the yafP genes are conserved in the majority of E. coli natural isolates. Therefore, we studied if these proteins are functionally linked. Using a murine septicaemia model, we showed that YafP activity reduced the bacterial fitness in the absence of PolIV. Similarly, YafP increased cytotoxicity of two DNA damaging nitroaromatic compounds, 4-nitroquinoline-1-oxide (NQO) and nitrofurazone, in the absence of PolIV. The fact that PolIV counterbalances YafP-induced cytotoxicity could explain why these two genes are transcriptionally linked. We also studied the involvement of YafP in genotoxic-stress induced mutagenesis and found that PolIV and YafP reduced NQO-induced mutagenicity. The YafP antimutator activity was independent of the PolIV activity. Given that YafP was annotated as a putative acetyltransferase, it could be that YafP participates in the metabolic transformation of genotoxic compounds, hence modulating the balance between their mutagenicity and cytotoxicity.
Neural networks SIR—Baxt's review of the clinical application of neural network methods (Oc... more Neural networks SIR—Baxt's review of the clinical application of neural network methods (Oct 28, p 1135) suggested benefits over standard techniques for the analysis of pathophysiological processes. In respect of cancer outcome prediction we suggest that the validity of this conclusion is uncertain because the studies Baxt cites do not include statistical tests of the significance of the results. Our review of how such results might be formally tested yields two important general principles, illustrated by considering the studies Baxt cites.
Spinal muscular atrophy (SMA) is characterised by degeneration of anterior horn cells of the spin... more Spinal muscular atrophy (SMA) is characterised by degeneration of anterior horn cells of the spinal cord and represents the second most common, lethal, autosomal recessive disorder after cystic fibrosis. Based on the criteria of the Internatinal SMA Consortium, childhood SMAs are classified into type I (Werdnig-Hoffmann disease), type II (intermediate form), and type III (Kugelberg-Welander disease).
The spinal form of Charcot-Marie-Tooth disease (spinal CMT) is a rare genetic disorder of the per... more The spinal form of Charcot-Marie-Tooth disease (spinal CMT) is a rare genetic disorder of the peripheral nervous system, the genetic basis of which remains unknown. To test the hypothesis that a defect of survival motor neuron (SMN), the determining gene for spinal muscular atrophy (SMA), would result in spinal CMT, 18 unrelated spinal CMT patients were studied. Nine of them were sporadic cases and the other nine belonged to unrelated autosomal dominant pedigrees. None of the 18 patients showed deletions involving SMN exons 7 or 8, the most frequent gene alteration found in SMA. In addition, haplotype analysis in two large autosomal dominant pedigrees showed that the 5q13 locus was not segregating with the spinal CMT locus. Therefore, neither the sporadic nor the familial cases of spinal CMT are associated with a SMN gene deletion, nor are the familial cases linked to the 5q13 region, indicating that this neuropathy is genetically different from SMA.
We report on a 38-day-old infant who developed pleuropneumonia due to a Staphylococcus aureus str... more We report on a 38-day-old infant who developed pleuropneumonia due to a Staphylococcus aureus strain responsible for familial furunculosis, which was acquired by maternal breast-feeding. All isolates from the infant and parents were genetically related by randomly amplified polymorphic DNA analysis and produced Panton-Valentine leukocidin.
An anonymous 14.9-kb rrn -containing HindIII fragment is strongly linked to Escherichia coli stra... more An anonymous 14.9-kb rrn -containing HindIII fragment is strongly linked to Escherichia coli strains causing neonatal meningitis. We show in this report that this fragment does not encode new virulence factors but lacks arpA , a gene common in avirulent E. coli strains, and we developed a PCR test to detect this fragment.
The survival motor neuron (SMN) gene was lacking in 6/12 patients with arthrogryposis multiplex c... more The survival motor neuron (SMN) gene was lacking in 6/12 patients with arthrogryposis multiplex congenita (AMC) associated with spinal muscular atrophy (SMA). Neither point mutation in the SMN gene nor evidence for linkage to chromosome 5q13 were found in the other patients. Hitherto, arthrogryposis was regarded as an exclusion criterion in SMA. Our data strongly suggest that AMC of neurogenic origin is genetically heterogeneous, with a subgroup being allelic to SMA. Absence or interruption of the SMN gene in the AMC-SMA association will make the diagnosis easier and genetic counselling will now become feasible.
In their molecular epidemiological analysis of Escherichia coli urosepsis isolates, Bingen-Bidois... more In their molecular epidemiological analysis of Escherichia coli urosepsis isolates, Bingen-Bidois et al. interpret the finding of a pathogenicity island (PAI) II J96-like domain in multiple ribotypes as conflicting with previous reports, which ostensibly describe this element as being confined to a single clone (1). This is potentially misleading, since the two references cited actually pertain to papG allele I, which is a hallmark of a different PAI from that of strain J96, i.e., PAI I. Indeed, papG allele I, which was absent from the population analyzed by Bingen-Bidois et al. (rather than being found in multiple ribotypes), is quite rare, having been found almost exclusively in strains closely related to strain J96 (4). In contrast, many previous reports have documented the co-occurrence of papG allele III, hly, and cnf1 (which implies the presence of a PAI II J96-like domain, as discussed by Bingen-Bidois et al.) in multiple group B2-derived lineages (3). These include clonal groups 1 and 2 of Cherifi et al. (2) (which equate, respectively, electrophoretic types [ETs] 1 and 21 of Whittam et al. [7] and ETs 47 and 42 of Maslow et al. [6], the latter clonal group including archetypal strain 536), the O2:K5/K7:H1 clonal group (ET 39 of Maslow et al.), and the O18:K1:H7 clonal group that includes archetypal strains RS218 (meningitis) and NU14 (cystitis) (3, 5).
Communicated by Sergio Ottolenghi Spinal muscular atrophy (SMA) is a common autosomal recessive d... more Communicated by Sergio Ottolenghi Spinal muscular atrophy (SMA) is a common autosomal recessive disease. SMA is linked to the 5q13 locus in 95% of patients, and in at least 98% of them, the SMN1 homozygous deletion is found. Compound heterozygous patients, who have an SMN1 deletion associated with a subtle mutation, appear undeleted with the common molecular diagnostic test that detects only the homozygous absence of SMN1. In these patients, mutation screening in SMN1 is hampered by the presence of several copies of the highly homologous SMN2 gene. Here, we present a rapid and reliable strategy for detecting SMN mutations using long-range PCR, which avoids cloning and cDNA analysis. Using this method, we found 10 mutations, including five mutations never reported previously and five recurrent mutations; some of them are probably population-specific. Marker analysis of the 5q13 locus in these mutations showed common haplotypes, supporting the hypothesis of a common ancestor rather than a hot spot sequence. We also evaluate the suitability of automated SSCA and DHPLC for mutation scanning. Hum Mutat 24:417-427, 2004.
Recently, a spinal muscular atrophy (SMA) determining gene, termed survival motor neuron (SMN) ge... more Recently, a spinal muscular atrophy (SMA) determining gene, termed survival motor neuron (SMN) gene, has been isolated from the 5q13 region and found deleted in most patients. A highly homologous copy of this gene has also been isolated and located in a centromeric position. We have analyzed 158 patients (SMA types I-IV) and found deletions of SMN exon 7 in 96.8%. Mutations other than gross deletions seem to be extremely rare. In one of the undeleted SMA type I patients, a newborn who survived for only 42 days, we detected a maternally inherited 5 bp microdeletion in exon 3, resulting in a premature stop codon. By RT-PCR and long range PCR amplification we were able to show that the deletion belongs to the SMN gene, rather than to the centromeric copy, and that the proposita had no paternal SMN gene. Analysis of the neuronal apoptosis inhibitor protein (NAIP) gene, which maps close to SMN and has been proposed as a SMA modifying gene, suggests the presence of at least one fulllength copy. Haplotype analysis of closely linked polymorphic markers suggests that the proposita also lacks the maternally derived copy of the centromeric homologue of SMN supporting the hypothesis that the severity of the phenotype might depend on the reduced number of centromeric genes in addition to the frameshift mutation.
Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder characterize... more Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder characterized by degeneration of motor neurons of the spinal cord and muscular atrophy. SMA is caused by alterations to the survival of motor neuron (SMN) gene, the function of which has hitherto been unclear. Here, we present immunoblot analyses showing that normal SMN protein expression undergoes a marked decay in the postnatal period compared with fetal development. Morphological and immunohistochemical analyses of the SMN protein in human fetal tissues showed a general distribution in the cytoplasm, except in muscle cells, where SMN protein was immunolocalized to large cytoplasmic dot-like structures and was tightly associated with membrane-free heavy sedimenting complexes. These cytoplasmic structures were similar in size to gem. The SMN protein was markedly deficient in tissues derived from type I SMA fetuses, including skeletal muscles and, as previously shown, spinal cord. While our data do not help decide whether SMA results from impaired SMN expression in spinal cord, skeletal muscle or both, they suggest a requirement for SMN protein during embryo-fetal development.
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Papers by O. Clermont