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C Junien

Publications and source records attributed to C Junien.

At least 91 records · Page 5Linked to original sources
PubMed1993

Subregional physical mapping of an alpha B-crystallin sequence and of a new expressed sequence D11S877E to human 11q.

We report the regional assignment on Chromosome (Chr) 11q of two cDNA clones selected as sequences expressed in mature kidney and not expressed in Wilms' tumor. Clone T70 was identified as an alpha B-crystallin sequence (CRYA2). CRYA2 has previously been mapped to 11q22.3-23.1 by in situ hybridization. Clone 6.2 represents a new gene expressed in adult and fetal kidney, pancreas, and liver. In order to map sequences corresponding to clone 6.2 and to physically define the boundaries of the localization of CRYA2, we used somatic cell hybrids carrying either different human chromosomes or Chr 11 segments and a cell line established from a patient with an interstitial deletion of region 11q14.3-q22.1. We showed that CRYA2 lies proximal to the 11q23.2 breakpoint defined by the constitutional t(11;22) and distal to the 11q22.1 breakpoint (between D11S388 and D11S35) of a constitutional interstitial deletion. This is in agreement with previous data obtained by in situ hybridization and provides proximal and distal physical benchmarks for this localization. Clone 6.2-related sequence (D11S877E) was assigned to region 11q23.2-q24.2 defined by the breakpoints of the constitutional t(11;22) and of the Ewing's sarcoma neuroepithelioma t(11;22).

Animals↗
PubMed1993

Myotonic dystrophy: absence of CTG enlarged transcript in congenital forms, and low expression of the normal allele.

Myotonic dystrophy (DM) is an autosomal dominant neuromuscular disease. The mutation has been identified as an unstable trinucleotide CTG repeat in a sequence encoding a putative cAMP-dependent protein kinase. The CTG repeat varies in length between affected siblings, and generally increases through generations in parallel with increasing severity of the disease. Congenital myotonic dystrophy, which represents the most severe phenotype, is exclusively maternally inherited. In this report, we show, by Northern blot analysis, that no mutated enlarged transcript is detectable in a 20-week-old DM fetus and in two congenitally affected infants. Furthermore, in skeletal and cardiac muscle of the DM fetus, we observed by RNA analysis, including Northern blot and RT-PCR, an unexpectedly low expression of the paternal wild type allele. Varying degrees of expression of the mutant and/or the normal allele might therefore account for the characteristic features of the congenital form and the extreme variability of the disease.

Alleles↗
PubMed1993

Chromosomal assignment of the uromodulin gene (UMOD) to 16p13.11.

We report the chromosomal assignment on chromosome arm 16p of a cDNA clone isolated through its expression in mature kidney and lack of expression in several Wilms tumors. DNA sequencing and analysis of the pattern of RNA expression in different tissues identified this clone as a uromodulin (Tamm-Horsfall glycoprotein, uromucoid; UMOD) sequence. By hybridizing this clone to somatic cell hybrids carrying different human chromosomes or segments of chromosome 16, the gene for UMOD was localized to 16p13.11.

Animals↗
PubMed1993

Somatic mosaicism for partial paternal isodisomy in Wiedemann-Beckwith syndrome: a post-fertilization event.

Genomic imprinting has been implicated in the aetiology of an overgrowth cancer-prone syndrome, the Wiedemann-Beck-with syndrome (WBS). We have demonstrated uniparental disomy (UPD) for paternal chromosome 11p markers in 5 out of 25 sporadic cases (20%). Delineation of the extent of the disomy region may help in understanding the mechanism and the stage, meiotic or mitotic, of disomy formation in this disease and in associated tumours. Our current studies in WBS patients with seventeen 11p and one 11q markers reveal paternal isodisomy, not heterodisomy, in the five cases. For one case we demonstrate unambiguously that partial isodisomy for 11p and somatic mosaicism for UPD resulted from a post-fertilization event. The restriction of isodisomy to part of 11p in another case, and somatic mosaicism for UPD in three other cases, suggest a mitotic recombinational event that must have occurred after fertilization. Mosaic phenotypes reflect the timing of their origin and the fate of the cells involved, as well as the cell-specific pattern of imprinting. Somatic mosaicism for UPD in four cases may thus explain the incomplete forms of WBS. The association of hemihypertrophy in sporadic WBS and even some cases of isolated hemihypertrophy. This is in agreement with a recent report of paternal isodisomy for 11p markers in a patient with hemihypertrophy, Wilms' tumour and adrenocortical carcinoma. Moreover, the risk of developing a tumour seems higher (50%) for patients with paternal 11p UPD than for WBS patients in general (7.5%).

Adult↗
PubMed1993

Testing genomic imprinting in Wilm's tumor.

Data from 511 cases of Wilms' tumor in France (including 12 familial cases) and 8 pedigrees from the literature were analyzed to test three modifications of Knudson's classical bimutational theory, based on genomic imprinting in Wilms' tumor carcinogenesis. Analysis of data of age at diagnosis and segregation analysis were performed to determine the number of independent events for Wilms' tumor development and to search for a differential role of paternal and maternal alleles. Unexpectedly, we show that only one rare event is required for tumor development in isolated unilateral cases which are considered to be mainly nonhereditary. In familial cases, we observe no effect of the sex of the transmitting parent on either hge at diagnosis or segregation ratio. We show that this could be explained by models of genomic imprinting which assume two nonindependent events, or only one rare genetic event. In bilateral cases we show a bimodality for age at diagnosis which could be due to a mixture of hereditary and nonhereditary cases. This result completely questions the classical assumption according to which all bilateral cases would be hereditary. These findings support the hypothesis that this childhood cancer arises from a variety of etiological pathways and might be useful to find strategies for further molecular investigations.

Adolescent↗
PubMed1993

Myotonic dystrophy: size- and sex-dependent dynamics of CTG meiotic instability, and somatic mosaicism.

Myotonic dystrophy (DM) is a progressive neuromuscular disorder which results from elongations of an unstable (CTG)n repeat, located in the 3' untranslated region of the DM gene. A correlation has been demonstrated between the increase in the repeat number of this sequence and the severity of the disease. However, the clinical status of patients cannot be unambiguously ascertained solely on the basis of the number of CTG repeats. Moreover, the exclusive maternal inheritance of the congenital form remains unexplained. Our observation of differently sized repeats in various DM tissues from the same individual may explain why the size of the mutation observed in lymphocytes does not necessarily correlate with the severity and nature of symptoms. Through a molecular and genetic study of 142 families including 418 DM patients, we have investigated the dynamics of the CTG repeat meiotic instability. A positive correlation between the size of the repeat and the intergenerational enlargement was observed similarly through male and female meioses for < or = 0.5-kb CTG sequences. Beyond 0.5 kb, the intergenerational variation was more important through female meioses, whereas a tendency to compression was observed almost exclusively in male meioses, for > or = 1.5-kb fragments. This implies a size- and sex-dependent meiotic instability. Moreover, segregation analysis supports the hypothesis of a maternal as well as a familial predisposition for the occurrence of the congenital form. Finally, this analysis reveals a significant excess of transmitting grandfathers partially accounted for by increased fertility in affected males.

Adult↗
PubMed1992

Diagnosis of Duchenne and Becker muscular dystrophies by polymerase chain reaction. A multicenter study.

OBJECTIVE--To assess the efficiency, reliability, and ease of use of DNA diagnosis for Duchenne and Becker muscular dystrophies (DMD/BMD) using the polymerase chain reaction (PCR). DESIGN--DNA from the patients was screened for deletion mutations using multiplex PCR, and the results were compared with those obtained by Southern blot analysis. The PCR multiplex reaction detects nine specific "hot-spot" exons in the dystrophin gene while the Southern analysis detects 66 specific dystrophin gene restriction fragments. The multiplex reaction requires 50-fold less DNA than Southern analysis and thus is considerably more sensitive. SETTING--Fourteen university-affiliated and private genetic disease diagnostic laboratories. PATIENTS--Male patients with clinical signs of DMD/BMD. Cases were selected for analysis randomly, without knowledge of whether a deletion was present within the dystrophin gene. MAIN OUTCOME MEASURES--The percentage of cases that were detectable by multiplex PCR in comparison with Southern analysis, the frequency, extent, and location of the detected deletion mutations. In some cases, duplication mutations were monitored. RESULTS--The accuracy of a single PCR multiplex amplification (nine exons) was compared with Southern analysis with 10 cDNA probes that cover the full length of the gene. The multiplex PCR analytic method detected 82% of those deletions detected by Southern analysis methods. In one of 745 analyses, the multiplex method suggested a single exon deletion, which was not confirmed by Southern analysis, representing a false-positive rate of 0.013%. CONCLUSIONS--Multiplex PCR represents a sensitive and accurate method for deletion detection of 46% of all cases of DMD/BMD. The method requires 1 day for analysis, is easy to perform, and does not use radioactive tracers. As such, multiplex PCR represents an efficient and rapid method for prenatal or postnatal diagnosis of DMD/BMD.

Blotting, Southern↗
PubMed1992

Screening for new mutations in the LDL receptor gene in seven French familial hypercholesterolemia families by the single strand conformation polymorphism method.

To investigate the molecular basis of familial hypercholesterolemia (FH) in France, we applied the single strand conformation polymorphism (SSCP) method to the promoter region and the 18 exons of the low density lipoprotein receptor (LDLR) gene. Seven probands, 4 heterozygotes, 2 compound heterozygotes, and 1 homozygote, belonging to FH families were tested. In all cases, previous genetic analysis and/or LDL receptor fibroblast assay had shown that the disease was due to defects in the LDLR gene. Out of the nine mutations expected, one nonsense mutation in exon 2 and six missense mutations were identified in exons 3, 6, 8, 11, and 15. Two of the latter were found in exon 6. In each family, cosegregation of the base substitution and the disease was observed. Ninety-five control subjects were screened for the presence of the six missense mutations. None was detected, implying that the mutations identified are deleterious. Our results indicate that the SSCP analysis of amplified genomic DNA fragments can be successfully used to rapidly screen mutation containing exons in large genes. Furthermore, all these mutations are newly described and demonstrate heterogeneity of LDLR gene mutations responsible for FH in the French population, as in other reported Caucasian populations.

Amino Acid Sequence↗
PubMed1992

Beckwith-Wiedemann syndrome, tumourigenesis and imprinting.

The concurrent development of cytogenetic, clinical, genetic and molecular studies has led to the recognition that the different hereditary and non-hereditary forms of the Beckwith-Wiedemann syndrome and associated tumours result from an imbalance between maternal and paternal alleles. The most exciting development in the past year was the discovery of uniparental paternal disomy and the increased understanding, arising from studies in the mouse and in hereditary cases, of the role possibly played by imprinting and somatic mosaicism in partial and complete expression of this complex syndrome.

Alleles↗
PubMed1992

A linkage map of 10 loci flanking the Marfan syndrome locus on 15q: results of an International Consortium study.

Members of an International Consortium for Linkage Analysis of the Marfan Syndrome (MFS1) have pooled data for joint analysis in an attempt to determine the precise location of the MFS1 gene and the order of 10 DNA markers on 15q. Five laboratories performed a total of 2111 genotypes in 22 families consisting of 225 affected and 248 normal subjects. For each marker a mean of 98 meioses was informative. D15S48 and D15S1 were identified as the closest linked markers with 99% upper confidence intervals of 12% and 13% respectively. We have used the CRI-MAP program to construct the most likely order as: D15S24-D15S25-D15S1-MFS1-D15S48-D15S49+ ++-(D15S45/S51)-(D15S29/S38). Placement of D15S2 in relation to -D15S1-D15S48- cannot be determined with certainty. The genetic map of these markers extends 53.6 cM in males and 65.0 cM in females with a sex averaged map of 60.7 cM. The sex difference was statistically significant (p = 0.005). Linkage heterogeneity between 22 MFS1 families was documented (p = 0.009) necessitating the exclusion of one family from the analysis. However, comparison of the remaining 21 families for two point and multipoint lod scores showed no evidence for linkage heterogeneity of the MFS1 locus.

Chromosome Mapping↗
PubMed1992

Beckwith-Wiedemann syndrome: a demonstration of the mechanisms responsible for the excess of transmitting females.

Beckwith-Wiedemann syndrome (BWS) is often associated with embryonal tumours (nephroblastoma, adrenocortical carcinoma, hepatoblastoma, and rhabdomyosarcoma). Several pedigrees have been reported strongly suggesting autosomal dominant inheritance and an excess of transmitting females was noticed in these families. We confirmed this excess using 19 published pedigrees and showed that this excess was for two reasons: first, reduced fecundity in affected males compared to females in a ratio of 1:4.6, and, second, a smaller risk of being affected in a ratio of 1:3 for subjects having inherited the gene from their father. These latter findings suggest genomic imprinting. Furthermore, considering these results together with other observations, such as the parental origin of the 15p15.5 duplication and the existence of uniparental disomy in some sporadic cases, we propose that overgrowth in BWS patients and malignant proliferation in associated tumours reflect an imbalance between paternal and maternal alleles.

Beckwith-Wiedemann Syndrome↗
PubMed1991

Germline mutations in the Wilms' tumor suppressor gene are associated with abnormal urogenital development in Denys-Drash syndrome.

Denys-Drash syndrome is a rare human condition in which severe urogenital aberrations result in renal failure, pseudohermaphroditism, and Wilms' tumor (nephroblastoma). To investigate its possible role, we have analyzed the coding exons of the Wilms' tumor suppressor gene (WT1) for germline mutations. In ten independent cases of Denys-Drash syndrome, point mutations in the zinc finger domains of one WT1 gene copy were found. Nine of these mutations are found within exon 9 (zinc finger III); the remaining mutation is in exon 8 (zinc finger II). These mutations directly affect DNA sequence recognition. In two families analyzed, the mutations were shown to arise de novo. Wilms' tumors from three individuals and one juvenile granulosa cell tumor demonstrate reduction to homozygosity for the mutated WT1 allele. Our results provide evidence of a direct role for WT1 in Denys-Drash syndrome and thus urogenital system development.

Acute Kidney Injury↗