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Biomedical subjects

B Simon-Bouy

Publications and source records attributed to B Simon-Bouy.

At least 19 recordsLinked to original sources
PubMed1995

Screening of CYP21 gene mutations in 129 French patients affected by steroid 21-hydroxylase deficiency.

The frequency of 12 different mutations of the steroid 21-hydroxylase gene (CYP21) was investigated in 129 French patients affected by congenital adrenal hyperplasia (CAH) due to steroid 21-hydroxylase deficiency. Eighty-nine percent of the CAH chromosomes were characterized. The most frequent mutations were a C-G substitution in intron 2, the deletion of the CYP21 gene and a T-A substitution in exon 4 in the severe form of the disease, and a G-T substitution in exon 7 in the nonclassic form. The correlation between the genotypes and the clinical forms of the disease showed marked variation in the phenotype from a single genotype, suggesting that individual variation and undetected additional mutations on the same CAH chromosome accounted for the phenotype. In 65 informative meioses of CAH families, no de novo mutation was found.

Adrenal Hyperplasia, Congenital↗
PubMed1995

Hyperechogenic fetal bowel: an ultrasonographic marker for adverse fetal and neonatal outcome.

OBJECTIVE: Fetal hyperchogenic bowel is associated with a variety of conditions, the incidence of which has yet to be studied. STUDY DESIGN: The outcomes of 182 cases of fetal hyperechogenic bowel were reviewed. Screening for maternal toxoplasmosis, fetal karyotyping, and amniotic fluid digestive enzyme assays were performed in all cases. Eight mutations associated with cystic fibrosis were analyzed in 116 cases. RESULTS: Of 135 newborns, 121 were normal, but nine underwent surgery for gastrointestinal obstruction, three had cytomegalovirus or parvovirus infection, one had a triple X chromosome, and one died from sudden infant death syndrome. In utero fetal death was observed in 24 cases. Elective termination of pregnancy was performed in 23 cases for associated anomalies. CONCLUSIONS: Hyperechogenic fetal bowel was associated with increased risk for adverse outcome. Prenatal management should include ultrasonographic surveillance, fetal karyotyping, amniotic digestive enzyme assays, and screening for cystic fibrosis and infectious disease.

Amniocentesis↗
PubMed1994

Transition from normal to premutated alleles in fragile X syndrome results from a multistep process.

In fragile X syndrome, the most common cause of inherited mental retardation, phenotypic expression has been linked to a region containing a repetitive sequence, (CGG)n, that appears to lengthen dramatically in fragile X patients and to show length variation in normal individuals. In order to investigate possible mechanisms responsible for further expansion of CGG in the normal population, we selected 31 normal unrelated X chromosomes carrying either the high-risk DX204-AC155 or DX196-AC151 haplotypes, as defined by the flanking microsatellites, DXS548 and FRAXAC2. Nearly 100% of CGGs with more than 35 repeats were found on DX204-AC155 haplotypes, with a mean length significantly higher and much more variable than in normal individuals carrying other haplotypes including the high-risk haplotype DX196-AC151. These findings suggest that the transition from the normal to the abnormal range occurs by a multistep process, a primary event, such as unequal crossing-over, leading to increased size and moderate instability of the repeat, and from which DNA polymerase slippage could lead to recurrent premutations. Our results also suggest that the upper limit of the normal range is roughly 35 repeats in the fragile X gene. The 36-54 repeats range would define an intermediate allele only observed, up to now, in DX204-AC155 fragile X chromosomes.

Analysis of Variance↗
PubMed1993

Molecular analysis of a ring chromosome X in a family with fragile X syndrome.

The phenotypically normal sister of a patient affected by fragile X syndrome was referred for genetic counselling and was found to carry a mosaic karyotype 46,X,r(X)/45,X. Because the probability of the simultaneous chance occurrence of fragile X syndrome and a ring chromosome X in the same family is very low, we postulated that the breakpoint of the ring chromosome X originated in the cytogenetic break in Xq27.3 responsible for fragile X syndrome. In order to determine the relative positions of the breakpoint on the ring chromosome X and the (CGG)n unstable sequence responsible for the fragile X mutation, we used molecular markers to analyse the telomeric regions of chromosome X in this family. The results showed that the ring chromosome X was the maternal fragile X chromosome and that the telomeric deletion on the long arm encompassed the (CGG)n sequence. This suggests that the cytogenetic break in Xq27.3 is distinct from the unstable (CGG)n sequence, or that the break followed by the end-to-end fusion creating the ring chromosome was not completely conservative. Analysis of DNA markers on the short arm of chromosome X evidenced a deletion of a large part of the pseudoautosomal region, allowing us to position the genes involved in stature and in some syndromes associated with telomeric deletions of Xp on the proximal side of the pseudoautosomal region.

Adult↗
PubMed1993

Oncogene-mediated propagation of tracheal epithelial cells from two cystic fibrosis fetuses with different mutations. Characterization of CFT-1 and CFT-2 cells in culture.

Primary tracheal epithelial cells obtained from two fetuses with cystic fibrosis (CF) were successfully transfected with a plasmid vector recombined with the large T oncogene of SV40. The resulting tracheal cells were propagated in culture for up to 25 passages and retained the mutations of the CF genes carried by the two fetuses, one heterozygous for the S549N and N1303K substitutions (CFT-1 cells), and the other homozygous for the most common deletion delta F508 (CFT-2 cells). The transfected cells: (a) expressed the SV40 large T oncogene, as determined by immunofluorescence and Northern blot analysis; (b) retained typical epithelial morphology, as assessed by the presence of microvilli, desmosomes, gap junctions, and cytokeratin expression; (c) were fully responsive to the cAMP-stimulating agents isoproterenol, forskolin and vasoactive intestinal peptide for cAMP production and PKA activation; (d) do not produce any tumour in the athymic nude mice; (e) were diploid and tetraploid with a normal chromosomal complement at early passages, and (f) exhibited the abnormal regulation of chloride conductance characteristic of CF. These results indicate that CFT-1 and CFT-2 cells constitute a suitable model for: (a) comparison of the maturation and function of the CFTR protein mutated in the two nucleotide-binding domains; (2) analysis of the biochemical defect in CF epithelial airway cells, (c) development of new therapeutic agents, and correction of the CF defect by gene replacement therapy in vitro.

Animals↗
PubMed1993

General cystic fibrosis mutations are usually missense mutations affecting two specific protein domains and associated with a specific RFLP marker haplotype.

Some 250 different mutations have so far been screened in the cystic fibrosis (CF) gene. The 50 nonsense, 33 splicing and 60 frameshift mutations are randomly distributed within the gene, unlike the 107 missense mutations or amino acid deletions. A large excess of missense mutations affects the exons encoding the first transmembrane (MS1) and first ATP-binding fold (NBF1) domains. Sixty-four of the 107 missense mutations may be classified as private, demic, local and general mutations on the basis of their geographic distribution in Europe. Private and demic mutations are randomly distributed within the gene; local and general mutations are not. It is well known that some RFLP markers are in linkage disequilibrium with some mutations. Private, demic and local mutations are randomly associated with each class of RFLP haplotypes. In contrast, general mutations, frequent and infrequent, are not randomly associated with RFLP markers. General mutations usually affect a specific part of the gene and are more likely to be associated with a specific RFLP marker. This suggests the existence of selective factors favoring these mutations, a hypothesis formerly postulated as a possible cause of the high frequency of the disease.

Cystic Fibrosis↗
PubMed1992

Carrier detection and prenatal diagnosis of cystic fibrosis using an intragenic TA-repeat polymorphism.

We have analysed the segregation of a TA-repeat polymorphism in intron 17b of the cystic fibrosis transmembrane conductance regulator gene responsible for cystic fibrosis (CF) in 23 French CF families non-informative for the delta F508 mutation (i.e. with at least one parent not carrying delta F508) or closely linked DNA markers. At least 13 different alleles ranging from 7 to 45 repeats were observed and the detected heterozygosity was 89%. Of the 23 families studied, 19 were fully informative for prenatal diagnosis or carrier detection, 3 were partially informative and one was not informative. In 6 families, prenatal diagnosis for CF or carrier detection in siblings of CF cases were performed using this polymorphism.

Base Sequence↗
PubMed1992

[Accidental ultrasonographic disclosure of isolated intra-abdominal fetal hyperechogenicity. Apropos of a series of 87 cases].

Having seen 87 cases we will now attempt to refine the management to be carried out when intra-abdominal hyperechogenic masses are found in the fetus. Before the 20th week of amenorrhoea (47 cases) amniocentesis can be used to study the digestive enzymes to determine the fetal karyotype. The normal results for intestinal enzymes makes it possible to rule out fetal cystic fibrosis. Three karyotype abnormalities were found in this series. After the 20th week (40 cases) intestinal enzymes cannot be interpreted. The diagnosis of cystic fibrosis then must rely on Delta F 508 mutation; but the absence of this mutation does not exclude cystic fibrosis. When ultrasound signs of intra-abdominal hyperechogenicity are found the diagnosis of cystic fibrosis should not be thought of first, because in this series the majority of fetuses who had this sign were born without any malformation. Four cases of cystic fibrosis that were confirmed have been found but equally there were other serious malformations, three chromosome abnormalities, four intestinal atresias, ten unexplained intra-uterine deaths and one case of biliary duct atresia.

Amniotic Fluid↗
PubMed1991

Functional insertion of the SV40 large T oncogene in cystic fibrosis intestinal epithelium. Characterization of CFI-3 cells.

Intestinal epithelial cells were isolated from a fetus with cystic fibrosis (CF) and transfected with a plasmid vector recombined with the ori- mutant of SV40. A population of proliferative cells was then subcloned and designated as CFI-3. These cells had a doubling time of 24 h and were maintained in culture for up to 25 passages. At passage 8, CFI-3 cells did not produce any tumors in nude mice. Northern blot and immunofluorescence studies indicated that the extended lifespan of CFI-3 cells results in genomic insertion of SV40 LT. Intestinal CFI-3 cells are epithelial, according to the expression of the human cytokeratin 18 gene and poorly differentiated by phase-contrast and electron microscopy. Functional membrane receptors activated by vasoactive intestinal peptide (VIP), its natural analogue pituitary adenylate cyclase activating peptide (PACAP-38), and isoproterenol were observed in CFI-3 cells. Restriction fragment length polymorphism analysis of the PstI KM19 site revealed that the cftr locus was identical in the chorionic villi and in CFI-3 cells. The manifestation of CF in this family was not related to the common mutation delta F508, since this fetus was heterozygous for the substitutions S549N and N1303K. Chloride transport, assessed by the 125I efflux, was induced in CFI-3 cells by the calcium inophore ionomycin, but not by the adenylate cyclase activator forskolin, and was inhibited by the chloride channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid. These results were confirmed in patch clamp studies in which the cpt cAMP analogue failed to stimulate membrane currents, while the calcium ionophore ionomycin stimulated inward currents. We conclude that intestinal CFI-3 cells retain the CF phenotype relating to defective regulation of Cl- channels, and therefore constitute a suitable model, 1) for elucidating the function of CFTR protein, 2) developing new therapeutic agents, and 3) correcting the CF defect by gene replacement therapy in vitro.

Antigens, Polyomavirus Transforming↗
PubMed1991

Consequences of prenatal diagnosis of cystic fibrosis on the reproductive attitudes of parents of affected children.

Three hundred and twenty-six French families with a cystic fibrosis-affected child who were referred for prenatal diagnosis were analysed by sibship size: 74.2 per cent of the couples had no further pregnancies to term after the affected child, who was deceased in 34.6 per cent of cases. These couples were followed prospectively after prenatal diagnosis and 77 had two or more consecutive pregnancies with prenatal diagnosis. The aim of these couples was to succeed in constituting a family with two normal children.

Alkaline Phosphatase↗
PubMed1991

Nearly 80% of cystic fibrosis heterozygotes and 64% of couples at risk may be detected through a unique screening of four mutations by ASO reverse dot blot.

A technique allowing the simultaneous screening of the four main CF mutations in the French population (delta F508, delta I507, G542X, S549N) has been developed by means of allele sequence-specific oligonucleotide (ASO) reverse dot blot. Using a strategy proposed by R. K. Saïki et al. (1989, Proc. Natl. Acad. Sci. USA 86: 6230-6234) for HLA-DQA, the seven ASOs for normal and mutant CF alleles were given a homopolymer T tail with terminal deoxyribonucleotidyltransferase and then immobilized on a nylon membrane. T-tail homopolymers were preferentially bound to the nylon, leaving the specific ASO sequences free to hybridize with amplified and radiolabeled exons 10 and 11 of a patient. These exons were simultaneously coamplified by a multiplex PCR and radiolabeled by random priming. ASO reverse dot blot currently appears to be the most efficient, rapid, and economic means of screening the population for CF mutations. This screening can detect nearly 80% of carriers and 64% of couples at risk and could prevent the birth of CF-affected infants in these families.

Alleles↗
PubMed1991

Nine mutations in the cystic fibrosis (CF) gene account for 80% of the CF chromosomes in French patients.

Thirteen mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene have been screened in a French sample of 185 cystic fibrosis (CF) patients, together with their respective associated RFLP haplotypes at the linked D7S23 locus (XV2C and KM19 markers). The respective frequencies of the mutations showed that 9 of them account for 80% of the CF chromosomes. Implications for prenatal diagnosis and heterozygote detection are defined and discussed. The well-known great excess of RFLP B marker within CF chromosomes is partially explained by two already characterized mutations highly associated with haplotype B: delta F508 and G542X. Similarly, the excess of haplotype D within CF chromosomes is partially explained by the association between delta I507 and this haplotype. These results may suggest the existence of two still untested or uncharacterized mutations, whose frequencies could be near 1%, one which would be associated with haplotype B and a second which would be associated with haplotype D. The possible cause of the specific association between most of the main different CF mutations and the RFLP haplotype B is discussed.

Alleles↗
PubMed1991

[Fortuitous discovery in echography of an isolated fetal intra-abdominal hyperechogenic mass. 87 cases].

Having seen 87 cases we will now attempt to refine the management to be carried out when intra-abdominal hyperechogenic masses are found in the fetus. Before the 20th week of amenorrhoea (47 cases) amniocentesis can be used to study the digestive enzymes to determine the fetal karyotype. The normal results for intestinal enzymes makes it possible to rule out fetal cystic fibrosis. Three karyotype abnormalities were found in this series. After the 20th week (40 cases) intestinal enzymes cannot be interpreted. The diagnosis of cystic fibrosis then must rely on Delta F 508 mutation; but the absence of this mutation does not exclude cystic fibrosis. When ultrasound signs of intra-abdominal hyper-echogenicity are found the diagnosis of cystic fibrosis should not be thought of first, because in this series the majority of fetuses who had this sign were born without any malformation. Four cases of cystic fibrosis that were confirmed have been found but equally there were other serious malformations, three chromosome abnormalities, four intestinal atresias, ten unexplained intra-uterine deaths and one case of biliary duct atresia.

Amniocentesis↗
PubMed1990

Localization of the gene for amiloride binding protein on chromosome 7 and RFLP analysis in cystic fibrosis families.

The apical sodium channel is essential for sodium reabsorption by the kidney. Its activity is blocked by the diuretic amiloride. Using a human cDNA coding for the amiloride binding protein (ABP), the corresponding structural gene was mapped to human chromosome 7q34-q36 by in situ hybridization. This region flanks the region implicated in cystic fibrosis (7q32). Because an alteration of the amiloride sensitive sodium channel function has been suggested in cystic fibrosis, a possible link between the ABP gene and this disease was analyzed by restriction fragments length polymorphism (RFLP) analyses. From this study, it appears that the gene coding for ABP is not directly modified by mutations causing cystic fibrosis.

Amine Oxidase (Copper-Containing)↗
PubMed1990

Studies of RFLP closely linked to the cystic fibrosis locus throughout Europe lead to new considerations in populations genetics.

The prenatal diagnosis of cystic fibrosis is now routinely performed by using two probes tightly linked to the CF locus (XV2C and KM19). These probes have been shown to exhibit a strong linkage disequilibrium with the CF locus. Our data (103 families) have been pooled with other French data (237 families). They are consistent with the hypothesis of a unique ancestral mutation initially associated with a B (D1E2) restriction fragment length polymorphism (RFLP) haplotype, subsequently reassociated by cross-over with A, C or D haplotypes. Assuming such an hypothesis, the mutation is supposed to be 3000-6000 years old, depending on generation length and the true recombination ratio between the KM19 and CF loci. Up-to-date Spanish, Danish and Greek data are reported together with other previously published population data in order to discuss the geographic origin and age of the mutation in Europe. The action of selection in terms of heterozygote advantage and distorsion of segregation is discussed.

Cystic Fibrosis↗