PubMed Health⌕ Search

Biomedical subjects

M Baens

Publications and source records attributed to M Baens.

34 records · Page 2Linked to original sources
PubMed1996

Biallelic alterations of both ETV6 and CDKN1B genes in a t(12;21) childhood acute lymphoblastic leukemia case.

Recently, a new recurrent t(12;21)(pl3;q22) has been identified in a B-cell lineage childhood acute lymphoblastic leukemia (ALL). The translocation results in a fusion of two known genes, ETV6/TEL (12p13) and AML1 (21q22), previously shown to be involved in the pathogenesis of myeloid disorders. We report results of cytogenetic fluorescence in situ hybridization and molecular studies of a B-cell childhood common ALL with a cryptic 12;21 translocation. Aberrations identified in this case involve both chromosomes 12 and include not only the ETV6-AML1 gene fusion and two different microdeletions of ETV6 but also the hemizygous loss of CDKN1B, D12S119, and KRAS2 loci and a putative rearrangement of the second CDKN1B allele as a result of an inv(12)(p13q24). Moreover, it was shown that the AML1-ETV6 reciprocal chimeric transcript was not present in the malignant cells, and hence may not play a major role in leukemogenesis. In addition, the putative loss of wild-type function of CDKN1B and ETV6 could indicate a synergistic effect of both genes in the pathogenesis of this leukemia case.

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

Genomic organization of TEL: the human ETS-variant gene 6.

We have constructed a detailed map of the genomic region containing the ETS-variant gene 6 (ETV6), involved in translocations and deletions associated with hematologic malignancies. Thirty-eight cosmids were characterized belonging to two contigs spanning 340 kb, and an EcoRl restriction map was developed. The gap between the two contigs, 2 kb in size, was closed by PCR. The contigs contain the complete coding sequence and the 5' and 3' UTRs of ETV6. Eight exons accounting for the ETV6 cDNA sequence were identified. The helix-loop-helix (HLH) motif is coded by exons 3 and 4, whereas exons 6-8 code for the ETS DNA-binding domain. All introns show consensus 5' donor and 3' acceptor splice sites. Introns 1 and 2 span 100 and 82 kb, respectively, and introns 3-7 range from 15 to 1.3 kb. An alternative exon 1 (exon 1B) is localized in intron 2. The 5' end of the ETV6 gene is associated with a CpG island characterized by the presence of four Notl, four Sacll, and three BssHll recognition sites and several SP1- and AP2-binding motifs. Alternative polyadenylation at the 3' end of the ETV6 gene generates the three transcripts of 6200, 4300, and 2400 nucleotides, respectively. The ETV6 gene spans 240 kb and is flanked at its 5' and 3' end by D12S1697 and D12S98, respectively. The markers D12S1095 and D12S89 are located in the first intron. Two new DNA polymorphisms were identified in the ETV6 gene, which will be useful for the analysis of loss of heterozygosity reported for the ETV6 gene in leukemia.

Base Sequence↗
PubMed1996

ETV6 gene rearrangements in hematopoietic malignant disorders.

Chromosomal abnormalities involving the short arm of chromosome 12 have been frequently observed in a broad spectrum of hematological malignancies. Recently, a gene located in this chromosomal region and implicated in leukemogenesis was identified. The gene, called ETV6 (previously known as TEL) is a new member of the ETS family, a group of genes thought to act as transcriptional activators. The gene spans 240 kb and consists of eight exons coding for a helix-loop-helix (HLH) and a DNA-binding domain. ETV6 was originally identified in a t(5;12)(q33;p13) occurring in a chronic myelomonocytic leukemia (CMML). Recent reports, however, show its involvement in a growing number of translocations associated with myeloid as well as lymphoid leukemias. At the molecular level fusions of ETV6 with PDGFRB (5q33), ABL (9q34), MNI(22q11) and AML1(21q22) have already been identified. Analysis of these chimeric proteins indicates that distinct domains of ETV6 can be involved in different fusion products, thus ETV6 can provide transcriptional and dimerization properties for partner genes, or the gene itself can act as an altered transcriptional factor. At least two clinico-pathological entities associated with ETV6 rearrangements have emerged as distinct disorders. The first one is a chronic myeloid malignancy characterized by t(5;12)(q33;p13), monocytosis and/or eosinophilia. The second entity is a type of childhood acute lymphoblastic leukemia (ALL) hallmarked by t(12;21)(p13;q22), and is shown to be the most frequent but cytogenetically largely undetectable chromosomal anomaly in childhood ALL.

Chromosome Mapping↗
PubMed1995

Isolation and regional assignment of human chromosome 12p cDNAs.

We have characterized 117 cDNAs isolated by direct cDNA selection using pools of human chromosome 12p cosmids. Sequencing revealed that 41 clones did overlap with other cDNAs. Of the remaining 76 cDNA sequences, 11 matched previously identified human chromosome 12p genes and 3 matched previously determined cDNA sequences, including the retinoblastoma binding protein 2 (RBBP2), the cyclin-dependent kinase inhibitor KIP1, and an expressed sequence tag. For each of the 76 cDNAs specific selection by a genomic cosmid clone was confirmed. STSs were developed for all cosmids, among them 3 polymorphic simple sequence repeats associated with, respectively, the TNFR related protein, CD27, and SCNN1. Regional assignment of the STSs by PCR analysis with somatic cell hybrids and fluorescence in situ hybridization showed that the majority of the loci map to chromosome 12p13, similar to the distribution of the known 12p genes. Evidence was found for the duplication on 12p of a region containing a polymorphic simple sequence repeat and sequences of two different cDNAs.

Base Sequence↗
PubMed1995

Mapping of an ordered set of 14 cosmids to human chromosome 12p by two-color in situ hybridization.

To map human chromosome 12p aberrations by fluorescence in situ hybridization (FISH), cosmids were isolated or obtained for 14 known 12p loci (D12S119, D12S158, D12S178, D12S370, D12S380E, A2M, CACNL1A1, FGF6, GAPD, KRAS2, PRB1, PZP, TPI1, and VWF). Using two-color FISH with three labeled probes to interphase nuclei, and to prometaphase chromosomes where possible, the order of these loci was sequentially determined to be pter-D12S158-D12S380E-CACNL1A1-FGF6- D12S370-VWF-GAPD-TPI1-A2M-PZP-PRB1-D12S 178-D12S119-KRAS2-cen. Two cell lines were analyzed with this set of cosmids. The EBV-transformed cell line TA carries a der(12) with a deletion of bands 12p13.1-->p11.2.D12S178, D12S119, and KRAS2 were absent in the der(12), whereas the other loci were present. The second cell line, GM01203A, exhibits a balanced t(4;12)(4q25; 12p13.3) with a breakpoint between FGF6 and D12S370.

Animals↗
PubMed1995

A physical map of the region spanning the chromosome 12 translocation breakpoint in a mesothelioma with a t(X;12)(q22;p13).

We have constructed a physical map of a 4.6-cM region of human chromosome band 12p13.3 that contains a translocation breakpoint from a mesothelioma with a t(X;12)(q22;p13). The map contains a contig of 22 yeast artificial chromosomes (YACs), onto which we have placed 18 sequence tagged site (STS) markers, including seven genes: D12S370, FGF6, KCAN1, KCNA5, KCNA6, NTF3, and VWF. A second YAC contig, comprised of 22 YAC clones, was located distal to the mesothelioma breakpoint and contained 12 STS markers, including four genes (CACNL1A1, D12S380E, D12S381E, and D12S382E). Based on STS content and fluorescence in situ hybridization experiments, two stable, nonchimeric YAC clones were found that span the mesothelioma breakpoint. A long-range restriction map of an 800-kb region was constructed and used to refine the mesothelioma breakpoint to a region of approximately 100 kb, flanked by the potassium channel genes KCNA1 and KCNA5. The latter was confirmed by direct visual hybridization (DIRVISH) experiments, using cosmids isolated for markers flanking the breakpoint as probes.

Animals↗
PubMed1994

Regional assignment of seven loci to 12p13.2-pter by PCR analysis of somatic cell hybrids containing the der(12) or the der(X) chromosome from a mesothelioma showing t(X;12)(q22;p13).

Two somatic cell hybrids containing the der(12) or the der(X) from a mesothelioma with a translocation t(X;12)(q22;p13) as the only chromosomal change were generated to characterize the region of 12p13 containing the translocation breakpoint. Fluorescence in situ hybridization analysis showed the breakpoint on chromosome 12 to occur between VWF and D12S158. On the linkage map developed by J. Weissenbach et al. (Nature, 1992, 359: 794-801), the breakpoints were located between D12S99 and D12S100 on chromosome 12 and between DXS1106 and DXS1001 on chromosome X. PCR analysis based on genomic sequences, with DNA from both somatic cell hybrids, enabled us to map CACNL1A1, FGF6, D12S370, D12S38OE, D12S381E, and D12S382E distally to the 12p13 breakpoint and to VWF.

Animals↗
PubMed1993

Construction and evaluation of a hncDNA library of human 12p transcribed sequences derived from a somatic cell hybrid.

An arrayed library of human heterogeneous nuclear complementary (hnc) DNA was constructed from a somatic cell hybrid (M28) containing an i(12p) marker as the sole human chromosome. Heterogeneous nuclear (hn) RNA of M28 was used to synthesize first-strand hncDNA with a primer (RT) containing a random hexanucleotide at its 3' end. Specific amplification of human sequences from this hncDNA was performed using Alu primers in combination with the RT primer. The products were directionally cloned and an arrayed library was constructed. Experiments indicated that all clones were derived from transcribed sequences. A number of randomly isolated clones were evaluated by Southern and Northern experiments, sequence analysis, and PCR. At least 80% of these clones were of human 12p origin. The number of independent clones in the library was estimated to be approximately 550. Using 60 hncDNA clones as probes, 6 showed positive signals on Northern blots. For 3 of these, the corresponding cDNAs were isolated: clone CD60A1 codes for the cation-dependent mannose 6-phosphate receptor, clone CC6 is a human homologue of the bovine 39-kDa nuclear-encoded NADH:ubiquinone oxidoreductase subunit, and CD18 belongs to the family of tumor necrosis factor receptor proteins. Southern experiments showed the 3 cDNAs to map to human chromosome 12p as expected. Taken together these results show that the generation of a hncDNA library is a useful tool for the isolation of unknown genes located on a human chromosome (fragment) present in a somatic cell hybrid.

Animals↗
PubMed1993

Rare HRAS1 alleles outside the VTR region in lymph nodes from patients with malignant lymphoma.

We found a new type of rare HRAS1 alleles arising de novo in the lymph node of lymphoma patients. Rare alleles of 6.2 kb (a0.1) and 7.3 kb (a2.3) are displayed in the presence of common alleles of 6.6 kb (a1) and 7.6 kb (a3), respectively. These rare alleles lack nucleotide sequences, present in the common alleles in the 5' part between the BamHI and XmaIII site. In addition, the rare alleles may have the classic A-G mutation in the intron at position 2719. In contrast to what is observed for rare constitutional alleles, the VTR region of these rare alleles has the same size as the common alleles. At present the significance of this new type of alleles is not clear.

Alleles↗
PubMed1993

Rapid DNA typing of class II HLA antigens using the polymerase chain reaction and reverse dot blot hybridization.

A nonisotopic oligotyping method using reverse dot blot hybridization was developed for HLA class II DQA1, DQB1, DPB1, DRB1, DRB3, DRB4, DRB5 alleles. The polymorphic second exon of the different genes was amplified by the polymerase chain reaction (PCR). For each gene the amplified DNA was hybridized at stringent conditions to membrane-bound sequence-specific oligonucleotides (SSOs) and visualization of positive signals was done by chemiluminescence. A combination of 11, 18, 23 and 31 SSOs was designed to identify 9/13 DQA1, 16/17 DQB1, 23/24 DPB1 and 50/55 DRB1, 4 DRB3, 1 DRB4, 3/4 DRB5 alleles respectively. For the DRB1 locus, an additional DRB1*04 group-specific PCR was developed to make discrimination between the DR4 alleles possible in different heterozygous combinations. The procedure described here provides rapid and nonisotopic genotyping of heterozygous samples from a variety of sources and can be applied for tissue typing, disease susceptibility studies and forensic medicine.

Alleles↗
PubMed1992

Simultaneous screening for 11 mutations in the cystic fibrosis transmembrane conductance regulator gene by multiplex amplification and reverse dot-blot.

An assay is described in which 11 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene can be screened simultaneously. Six different exons of the CFTR gene are amplified in a single multiplex amplification. Biotinylated dUTP is incorporated into the different fragments during the amplification process. A sample of this mixture is then hybridized to 21 different poly-dT tailed oligonucleotide probes which are bound to a nylon membrane. In order to screen the different mutations in a single step hybridization, the length of the different oligonucleotides and the amount used in the assay were optimized. The detection is performed by binding avidin-alkaline phosphatase to the biotin, followed by a chemiluminescent reaction. By means of this fast and sensitive assay, about 85% of all the cystic fibrosis mutations in the Belgian population can be detected.

Base Sequence↗
PubMed1991

Megakaryoblastic leukemia with an N-ras mutation and late acquisition of a Philadelphia chromosome.

A patient is described with de novo acute non-lymphocytic leukemia of megakaryoblastic lineage with tri-lineage myelodysplasia. This patient was studied cytogenetically and using molecular genetic techniques throughout her clinical course. She had an N-ras mutation at diagnosis which persisted despite a bone marrow transplant, and acquired a Philadelphia chromosome associated with a P190 BCR-ABL transcript at clinical relapse 3 months post-transplantation.

Adult↗