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Biomedical subjects

V Cacheux

Publications and source records attributed to V Cacheux.

At least 19 recordsLinked to original sources
PubMed2001

Loss-of-function mutations in SIP1 Smad interacting protein 1 result in a syndromic Hirschsprung disease.

Hirschsprung disease (HD) has been described in association with microcephaly, mental retardation and characteristic facial features, delineating a syndrome possibly caused by mutations localized at chromosome 2q22--q23. We have analyzed a de novo translocation breakpoint at 2q22 in one patient presenting with this syndrome, and identified a gene, SIP1, which is disrupted by this chromosomal rearrangement. SIP1 encodes Smad interacting protein 1, a new member of the delta EF1/Zfh-1 family of two-handed zinc finger/homeodomain transcription factors. We determined the genomic structure and expression of the human SIP1 gene. Further analysis of four independent patients showed that SIP1 is altered by heterozygous frameshift mutations causing early truncation of the protein. SIP1, among other functions, seems to play crucial roles in normal embryonic development of neural structures and neural crest. Its deficiency, in altering function of the TGF beta/BMP/Smad-mediated signalling cascade, is consistent with some of the dysmorphic features observed in this syndrome, in particular the enteric nervous system defect that underlies HD.

Abnormalities, Multiple↗
PubMed2000

Polydom: a secreted protein with pentraxin, complement control protein, epidermal growth factor and von Willebrand factor A domains.

To identify extracellular proteins with epidermal growth factor (EGF) domains that are potentially involved in the control of haemopoiesis, we performed degenerate reverse-transcriptase-mediated PCR on the murine bone-marrow stromal cell line MS-5 and isolated a new partial cDNA encoding EGF-like domains related to those in the Notch proteins. Cloning and sequencing of the full-length cDNA showed that it encoded a new extracellular multi-domain protein that we named polydom. This 387 kDa mosaic protein contained a signal peptide followed by a new association of eight different protein domains, including a pentraxin domain and a von Willebrand factor type A domain, ten EGF domains, and 34 complement control protein modules. The human polydom mRNA is strongly expressed in placenta, its expression in the other tissues being weak or undetectable. The particular multidomain structure of the encoded protein suggests an important biological role in cellular adhesion and/or in the immune system.

Amino Acid Sequence↗
PubMed2000

Analysis of uncultured amniocytes by comparative genomic hybridization: a prospective prenatal study.

Comparative genomic hybridization (CGH) is a new molecular cytogenetic technique which can detect and map whole and partial aneuploidies throughout a genomic specimen DNA without culturing specimen cells. Thus, CGH may be used as a comprehensive and rapid screening test in prenatal unbalanced chromosomal abnormalities detection. We report the results of the first prospective study to evaluate the use of the CGH technique on uncultured amniocytes. Seventy-one amniotic fluid samples, obtained by transabdominal amniocentesis between the 14th and 35th weeks of gestation, were simultaneously investigated using CGH and conventional cytogenetics. Amniocentesis were done for advanced maternal age (21.1%), fetal ultrasound anomalies (73.3%) and high level of biochemical markers in maternal serum (5.6%). Sixty-six (93%) informative results were generated on a total of 71 analysed specimens. Fifty-nine samples were reported as disomic for all autosomes with a normal sex chromosome constitution using CGH and conventional cytogenetics. Among them, three pericentromeric chromosomal inversions were undetected by CGH analysis. Seven numerical aberrations were characterized, including one case of trisomy 13, one case of trisomy 18 and five cases of trisomy 21. Advantages and limitations of CGH for a rapid prenatal screening of unbalanced chromosomal aberrations are discussed.

Amniocentesis↗
PubMed2000

The human dynein intermediate chain 2 gene (DNAI2): cloning, mapping, expression pattern, and evaluation as a candidate for primary ciliary dyskinesia.

Primary ciliary dyskinesia (PCD) is an autosomal recessive disease characterized by chronic sinusitis and bronchiectasis, and usually associated with hypofertility. Half of the patients present a situs inversus, defining the Kartagener's syndrome. This phenotype results from axonemal abnormalities of respiratory cilia and sperm flagella, i.e., mainly an absence of dynein arms. Recently, a candidate-gene approach, based on documented abnormalities of immotile strains of Chlamydomonas reinhardtii, allowed us to identify the first gene involved in PCD. Following the same strategy, we have characterized DNAI2, a human gene related to Chlamzydomonas IC69, and evaluated its possible involvement in a PCD population characterized by an absence of outer dynein arms. DNAI2, which is composed of 14 exons located at 17q25, is highly expressed in trachea and testis. No mutation was found in the DNAI2 coding sequence of the twelve patients investigated. However, ten intragenic polymorphic sites and an EcoRI RFLP have been identified, allowing the exclusion of DNAI2 in three consanguineous families.

Adolescent↗
PubMed2000

Mutations in LHX3 result in a new syndrome revealed by combined pituitary hormone deficiency.

Combined pituitary hormone deficiency (CPHD) has been linked with rare abnormalities in genes encoding transcription factors necessary for pituitary development. We have isolated LHX3, a gene involved in a new syndrome, using a candidate-gene approach developed on the basis of documented pituitary abnormalities of a recessive lethal mutation in mice generated by targeted disruption of Lhx3 (ref. 2). LHX3, encoding a member of the LIM class of homeodomain proteins, consists of at least six exons located at 9q34. We identified a homozygous LHX3 defect in patients of two unrelated consanguineous families displaying a complete deficit in all but one (adrenocorticotropin) anterior pituitary hormone and a rigid cervical spine leading to limited head rotation. Two of these patients also displayed a severe pituitary hypoplasia, whereas one patient presented secondarily with an enlarged anterior pituitary. These LHX3 mutations consist of a missense mutation (Y116C) in the LIM2 domain at a phylogenetically conserved residue and an intragenic deletion predicting a severely truncated protein lacking the entire homeodomain. These data are consistent with function of LHX3 in the proper development of all anterior pituitary cell types, except corticotropes, and extrapituitary structures.

Abnormalities, Multiple↗
PubMed1999

De novo inverted duplication 9p21pter involving telomeric repeated sequences.

We report on clinical and cytogenetic findings in a boy with partial 9p duplication, dup(9)(p21pter). Clinical manifestations included facial and hand anomalies and mental retardation. Fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) were used to characterize further and confirm the conventional banding data. Investigation by FISH using whole chromosome 9 paint probe showed that the additional material was derived from chromosome 9. Using CGH, a region of gain was found in the chromosome segment 9p21pter. YACs and telomeric probes confirmed the duplicated region. Using the all-human telomeric sequences probe, intrachromosomal telomeric signal was noted on the short arm of the abnormal chromosome 9. Mechanism of formation of the duplication, including intrachromosomal telomeric sequences, is discussed.

Abnormalities, Multiple↗
PubMed1999

Loss-of-function mutations in a human gene related to Chlamydomonas reinhardtii dynein IC78 result in primary ciliary dyskinesia.

Primary ciliary dyskinesia (PCD) is a group of heterogeneous disorders of unknown origin, usually inherited as an autosomal recessive trait. Its phenotype is characterized by axonemal abnormalities of respiratory cilia and sperm tails leading to bronchiectasis and sinusitis, which are sometimes associated with situs inversus (Kartagener syndrome) and male sterility. The main ciliary defect in PCD is an absence of dynein arms. We have isolated the first gene involved in PCD, using a candidate-gene approach developed on the basis of documented abnormalities of immotile strains of Chlamydomonas reinhardtii, which carry axonemal ultrastructural defects reminiscent of PCD. Taking advantage of the evolutionary conservation of genes encoding axonemal proteins, we have isolated a human sequence (DNAI1) related to IC78, a C. reinhardtii gene encoding a dynein intermediate chain in which mutations are associated with the absence of outer dynein arms. DNAI1 is highly expressed in trachea and testis and is composed of 20 exons located at 9p13-p21. Two loss-of-function mutations of DNAI1 have been identified in a patient with PCD characterized by immotile respiratory cilia lacking outer dynein arms. In addition, we excluded linkage between this gene and similar PCD phenotypes in five other affected families, providing a clear demonstration of locus heterogeneity. These data reveal the critical role of DNAI1 in the development of human axonemal structures and open up new means for identification of additional genes involved in related developmental defects.

Amino Acid Sequence↗
PubMed1998

Human Prop-1: cloning, mapping, genomic structure. Mutations in familial combined pituitary hormone deficiency.

Prop-1 is a newly isolated pituitary-specific paired-like homeodomain transcription factor whose cDNA sequence is well known in mouse. To study its involvement in human combined pituitary hormone deficiency (CPHD), we have isolated the human cDNA ortholog and determined the exon/intron organization and chromosomal localization of the human gene. A Prop-1 defect was characterized in three CPHD families. One missense mutation (R73C) involves a residue conserved in 95% of the more than 400 homeodomain proteins so far identified; in vitro splicing assays demonstrated the functional importance of the second defect, whereas the remaining mutation is a frameshift. Given the disease phenotype documented in the patients, these data, which will facilitate molecular investigations in other patients, demonstrate the crucial role of Prop-1 in the proper development of somatotrophs, lactotrophs, thyreotrophs and gonadotrophs.

Amino Acid Sequence↗
PubMed1998

Altered patterns of DNA methylation on chromosomes from leukemia cell lines: identification of 5-methylcytosines by indirect immunodetection.

An immunodetection technique has been developed to map with high resolution the methylated sites of human chromosomes. We have used this method to define the methylated areas of chromosomes from normal donors and from leukemia cell lines. The chromosomes were exposed for a short time to UV light to induce mild denaturation. The methylated sites were detected in situ by using monoclonal antibodies against 5-methylcytosine (prepared in mouse), and fluorescein-conjugated antimouse immunoglobulins. The chromosomes from normal cells exhibited a fluorescent pattern with RCT banding, although some differences from previously reported patterns could be detected. With this method we have been able to show the presence of two types of R-bands: High fluorescence R-band (HFR) and low fluorescence R-band (LFR). Chromosomes from leukemia cell lines exhibited low global staining with disrupted RCT banding of the chromosomes. The decreased level of the methylation status of the chromosomes from leukemia cells was confirmed by detection of 5-methylcytosines on total immobilized DNA. Thus, we have shown that this method can be used to determine the methylated status of chromosomes and, in turn, to map not only the structural (banding) but also the functional (methylation status) properties of the different chromosome domains in normal and pathologic human cells.

5-Methylcytosine↗
PubMed1998

Pentasomy 13q in a case of acute myelogenous leukemia (Mo).

A case of acute myelogenous leukemia Mo FAB subtype with a pentasomy 13q (associated with a trisomy 19 in a subclone) in the initial bone marrow metaphase cells is reported. The pentasomy 13q is the result of the presence of double isochromosome 13q and one normal chromosome 13. In our case, this abnormality had a poor prognosis.

Acute Disease↗
PubMed1998

Comparative genomic hybridization: technical development and cytogenetic aspects for routine use in clinical laboratories.

Comparative genomic hybridization (CGH) offers a new global approach for detection of chromosomal material imbalances of the entire genome in a single experiment without cell culture. In this paper, we discuss the technical development and the cytogenetic aspects of CGH in a clinical laboratory. Based only on the visual inspection of CGH metaphase spreads, the correct identification of numerical and structural anomalies are reported. No commercial image analysis software was required in these experiments. We have demonstrated that this new technology can be set up easily for routine use in a clinical cytogenetics laboratory.

Aneuploidy↗
PubMed1998

Comparison of comparative genomic hybridization with conventional karyotype and classical fluorescence in situ hybridization for prenatal and postnatal diagnosis of unbalanced chromosome abnormalities.

The comparative genomic hybridization (CGH) technique was initially used for detection of chromosomal imbalances in tumor cells. CGH can also be used as a supplementary method to karyotypic analysis in clinical cytogenetic cases. In order to evaluate CGH usefulness in prenatal and postnatal analysis of whole chromosome and segmental aneusomies, we investigated 13 clinical samples from blood, cultured chorionic villi, cultured amniotic fluids and uncultured amniotic fluids. These specimens, initially analyzed by conventional cytogenetics, included 5p monosomy, 9p duplication, add 6p, unbalanced translocation between chromosomes 5 and 10, mosaic tetrasomy 12p (50%), unbalanced (X;X) translocation and Prader-Willi deletion (15q11-13). In addition, six numerical chromosome aberrations (tetrasomy X, trisomies 13, 18, 21 and monosomy X) were analysed. All the chromosomal abnormalities, except the Prader-Willi deletion, were correctly detected by CGH. Here, we have demonstrated that the CGH technique is an alternative to classical fluorescence in situ hybridization using specific probes for detection of the unbalanced chromosomal aberrations in prenatal and postnatal diagnosis and could be used for rapid prenatal screening for unbalanced aberrations.

Amniotic Fluid↗
PubMed1997

ETV6 is the target of chromosome 12p deletions in t(12;21) childhood acute lymphocytic leukemia.

The presence of ETV6 deletions was investigated in 215 children with acute lymphoblastic leukemia (ALL) using the loss of heterozygosity (LOH) approach. We used four intragenic or juxtagenic microsatellite markers to detect allelic deletions. In this series of unselected patients, LOH of ETV6 markers was found in 23% of cases (6% of T-ALL and 26% of B lineage ALL) confirming that chromosome 12p12-13 deletions represent a major genetic alteration in childhood ALL, frequently missed by cytogenetic analysis. The presence of a t(12;21)(p13;q22) was studied by RT-PCR and/or FISH in a total of 134 patients (125 B lineage ALL, nine T-ALL) including 42 cases with LOH. Thirty-four out of 44 patients (77%) for whom a t(12;21) was observed displayed LOH of the ETV6 markers. When associated with a t(12;21), ETV6 is very likely to be the target of deletions as indicated by the detection of intragenic deletions in three patients. Although deletion of ETV6 and t(12;21) were associated in most patients, in eight cases (six B lineage and two T-ALL) LOH was detected at the ETV6 locus without ETV6-AML1 hybrid RNA. FISH studies conducted in five of these eight patients confirmed the absence of translocation involving ETV6. In such patients, the other allele of ETV6 could be disrupted by either a small deletion, a point mutation, or an epigenetic modification and it will be of interest to study the structure and expression of the remaining allele of ETV6 in these cases. Alternatively, a tumor suppressor gene located close to ETV6 and CDKN1B could be the target of deletions.

Adolescent↗
PubMed1997

Systematic screening for fragile X syndrome in a cohort of 574 mentally retarded children.

In this study, we evaluated the prevalence of the fragile X syndrome in a cohort of 574 mentally retarded children. The only inclusion criterion was the diagnosis of mental retardation according to the DSM-IIIR classification. We used a PCR-based strategy for the diagnosis of fragile X syndrome to facilitate systematic screening. This diagnostic scheme is based on an initial PCR to eliminate most fragile X-negative patients followed by Southern blotting for fragile X syndrome diagnosis. Altogether, 403 boys and 171 girls were tested. The prevalence of this genetic disorder was 1.9% (11/574) in the whole cohort and 2.5% (10/403) in boys. Only one case of fragile X syndrome was detected among the 171 girls tested (0.6%). Clinical examination, especially in the youngest children, was often unremarkable, and the only reason for suspecting fragile X syndrome was the presence of mental retardation. Thus, a systematic screening for the fragile X syndrome in mentally retarded children seems justified because of the importance of a precise diagnosis in genetic counseling.

Adolescent↗
PubMed1996

The 12;21 translocation involving TEL and deletion of the other TEL allele: two frequently associated alterations found in childhood acute lymphoblastic leukemia.

A recurrent t(12;21)(p13;q22) has recently been described in human acute lymphoblastic leukemias (ALLs). This translocation fuses TEL and AML1, two genes previously cloned from translocation breakpoints in myeloid leukemias. In addition, allelic loss of the TEL gene can be detected in 15% to 22% of childhood ALLs. In the present study, we have sought allelic deletions of TEL and the presence of the t(12;21) in 50 children with B-lineage ALL, using a combination of microsatellite typing, fluorescent in situ hybridization (FISH), and analysis of the fusion transcripts resulting from the TEL-AML1 gene fusion. Our results indicate that the association between the t(12;21) and the deletion of the nontranslocated allele of TEL is among the most frequent abnormalities observed in B-lineage ALLs. FISH analysis using several cosmid probes showed that, in one patient with a t(12;21) translocation involving TEL, the second allele had an intragenic deletion. This observation points to TEL as the actual target of 12p12-13 deletions in patients that associate a t(12;21) with a deletion. The TEL-AML1 fusion RNA was found in all patients with the t(12;21) whereas the reciprocal AML1-TEL transcript was only found in a subset of patients, suggesting that only the protein product encoded by TEL-AML1 is likely to play a role in leukemogenesis. The observation that, in two patients with the t(12;21), a deletion of TEL was only present in a subclone indicates that this deletion was a secondary event that occurred after the translocation. The frequent occurrence of TEL deletions in patients with t(12;21) suggests that the deletion of the normal TEL allele subsequent to the t(12;21) provides a further proliferative advantage to leukemic cells.

Adolescent↗
PubMed1996

Expression of p13MTCP1 is restricted to mature T-cell proliferations with t(X;14) translocations.

T-cell prolymphocytic leukemia (T-PLL), a rare form of mature T-cell leukemias, and ataxia telangiectasia clonal proliferation, a related condition occurring in patients suffering from ataxia telangiectasia, have been associated to translocations involving the 14q32.1 or Xq28 regions, where are located the TCL1 and MTCP1 putative oncogenes, respectively. The MTCP1 gene is involved in the t(X;14)(q28;q11) translocation associated with these T-cell proliferations. Alternative splicing generates type A and B transcripts that potentially encode two entirely distinct proteins; type A transcripts code for a small mitochondrial protein, p8MTCP1, and type B transcripts, containing an additional open reading frame, may code for 107 amino-acid protein, p13MTCP1. The recently cloned TCL1 gene, also involved in translocations and inversions associated with T-cell proliferations, codes for a 14-kD protein that displays significant homology with p13MTCP1. We have generated rabbit antisera against this putative p13MTCP1 protein and screened for expression of p13MTCP1 normal lymphoid tissues and 33 cases of immature and mature lymphoid T-cell proliferations using a sensitive Western blot assay. We also investigated the MTCP1 locus configuration by Southern blot analysis. The p13MTCP1 protein was detected in the three T-cell proliferations with MTCP1 rearrangements because of t(X;14) translocations, but neither in normal resting and activated lymphocytes nor in the other T-cell leukemias. Our data support the hypothesis that p13MTCP1 and p14TCL1 form a new protein family that plays a key role in the pathogenesis of T-PLL and related conditions.

Amino Acid Sequence↗
PubMed1996

[Waardenburg's syndrome].

Waardenburg syndrome is an autosomal dominant disorder characterised by sensorineural hearing loss, pigmentary abnormalities of iris, hair and skin and dystopia canthorum. The expression of clinical findings of Waardenburg syndrome is extremely variable. The potential sources of this variability include allelic variation, genetic heterogeneity, epistatic modifying genes and stochastic effects. This type of multifactorial inheritance based on oligogenic epistasis is very different from the model based on polygenic inheritance. Indeed in the first model, knowledge of the genotype at relevant modifier loci may allow prediction and possibly treatment of clinically relevant aspects of the phenotype. Therefore a more complete understanding of gene expression in Waardenburg could provide insights that are relevant to many other multifactorial diseases.

Animals↗