Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0013080 (Down syndrome)
 14,180 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human ETS2 and ERG genes are members of the ETS gene family, with sequence homology to the viral ets gene of the avian erythroblastosis retrovirus, E26. These genes are located on chromosome 21 and molecular genetic analysis of Down syndrome (DS) patients with partial trisomy 21 suggested that ETS2 may be a gene within the minimal DS genetic region. We have, in fact, been able to confirm the presence of the ETS2 gene dosage in triplicate occurring in occult human 21 chromosome abnormalities. It is known that ERG and ETS2 gene translocations occur in certain specific leukemias associated with defined chromosome rearrangements [e.g., t(8;21)]. Moreover, it is known that DS individuals are at greater risk for leukemic disease than their normal familial cohorts, implying that trisomy of that region of human chromosome 21 may play a role in the development of this type of neoplasia. The human ETS genes, first identified in our laboratory, are highly conserved, being found from lower organisms, like Drosophila and sea urchin, to humans. In mammals, the ETS genes are structurally distinct, located on separate chromosomes; they are transcriptionally active and differentially regulated. The ETS2 protein is phosphorylated and turns over with a half-life of approximately 20 min. After activation with the tumor promoter, TPA, the level of ETS2 elevates 5- to 20-fold. The properties of the ETS2 protein, such as nuclear localization, phosphorylation, rapid turnover, and response to protein kinase C, indicate that this protein belongs to a group of oncogene proteins thought to have regulatory functions in the nucleus. In the mouse thymus ets-1 and ets-2 are 8-10-fold higher, respectively, in the CD4+ subset than in other subsets examined, suggesting a role in T-cell development for these genes. Cells transfected with the cellular ets-2 gene, expressing higher levels of ets-2 products, showed a stimulated proliferation response, abolished their serum requirement and formed colonies in soft agar that could induce tumors in nude mice. Collectively, these data suggest that this family of genes might play a role in controlling specific steps of the signaling transduction pathway. Thus, the ETS genes, as other genes with homology to viral oncogenes, might be instrumental in regulating cellular growth and differentiation, as well as organismal development.
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PMID:ETS family of genes in leukemia and Down syndrome. 214 58

We describe a patient with an asymmetric double ring 21 in mosaic form, 45,XX, -21/46, XX, -21, +r(21), who has limited manifestations of Down syndrome and who developed acute myelofibrosis and megakaryocytic leukemia (AMKL), FAB M7, a hematologic disorder particularly common in Down syndrome patients. In situ hybridization studies, gene dosage, and DNA polymorphism analysis showed that the ring chromosome carries a duplicated region which extends from D21S406 on the centromeric side and includes marker D21S3 on the telomeric side. FISH studies indicate two sizes of ring 21 in the patient. The origin of the supernumerary chromosome 21 in the proband was paternal; furthermore, the r(21) probably was formed postzygotically. Included in the duplicated segment are the candidate genes for leukemia AML-1, ETS, and ERG. The potential significance of disomic homozygosity of loci on 21q in M7 megakaryocytic leukemia is discussed.
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PMID:Cytogenetic and molecular analysis of a ring (21) in a patient with partial trisomy 21 and megakaryocytic leukemia. 757 23

The triplication of a region of chromosome 21 around D21S55 in 21q22.2-22.3 has been involved in the main features of Down syndrome including mental retardation (Down syndrome chromosome region: DCR). To improve the physical map of this region, we screened yeast artificial chromosome (YAC) libraries with ETS2 and ERG sequences. Five selected clones were analyzed by AluPCR, pulsed-field gel electrophoresis, and in situ hybridization. A 1.2-Mg contig, encompassing the protooncogenes ETS2 and ERG, was identified, its restriction map established and compared to the genomic map. ERG is distal to D21S55 and proximal to ETS2. ERG and ETS2 genes are 400 kb apart and in opposite orientations. The contig contains the distal boundary and part of the DCR. Three putative HTF islands were identified.
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PMID:Mapping the Down syndrome chromosome region. Establishment of a YAC contig spanning 1.2 megabases. 806 51

Acute leukemia (AL) is a relatively uncommon, but dreaded, complication occurring with increased frequency in individuals with Down syndrome (DS). This selective update includes aspects of AL in DS in which a change or advancement in our understanding of this disease has occurred. Despite previous reports describing a worse outcome for these individuals, more recent studies have suggested an improved response to current treatment strategies (including high-dose AraC) equaling, or even surpassing, the survival of non-DS individuals with AL. An increased toxicity to methotrexate in DS patients has also been recognized. While the leukemia of DS infants has been described as megakaryoblastic, the spectrum of in vitro differentiation is much broader including (in addition to megakaryocytic colonies) various myeloid, macrophage, and even erythroid colonies. Although the cause(s) of DS-AL remains unknown, potential candidate genes include those encoded on chromosome 21 that play a role in other defined leukemias in non-DS individuals. The AML1/PEBP2alpha gene maps to the DS critical region and is characteristically associated with two leukemia-associated chromosomal translocations: 1) the 8;21 translocation involving an AML1/ETO fusion transcript commonly seen in acute myelogenous leukemia (AML) and; 2) a 3;21 translocation identified in certain chemotherapy-related myelodysplasias/leukemias and occasionally in the blast crisis of chronic myelogenous leukemia cells. Similarly, the ETS-related gene, ERG, involved in the AML 16;21 maps to the q22 region of chromosome 21. Lastly, a familial platelet disorder with a propensity to develop myeloid leukemia has been linked to 21q22.1-22.2 and conceivably might involve AML1, ERG or yet another gene.
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PMID:Down syndrome and leukemia, an update. 854 49

The Down syndrome (DS) region on chromosome 21, which is responsible for the main features of DS such as characteristic facial features, a congenital heart defect, and mental retardation, has been defined by molecular analysis of DS patients with partial trisomy 21. The 2. 5-Mb region around the marker D21S55 between D21S17 and ERG in 21q22 is thought to be important, although contributions of other regions cannot be excluded. In this region, we focused on a 1.6-Mb region between a NotI site, LA68 (D21S396, which is mapped distal to D21S17) and ERG, because analysis of a Japanese DS family with partial trisomy 21 revealed that the proximal border of its triplicated region was distal to LA68. We constructed P1 contigs with 46 P1 clones covering more than 95% of the 1.6-Mb region. A high-resolution restriction map using BamHI was also constructed for more detailed analysis. Our P1 contig map supplements other physical maps previously reported and provides useful materials for further analysis including gene isolation and sequencing of the DS region.
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PMID:A 1.6-Mb P1-based physical map of the Down syndrome region on chromosome 21. 861 11

Down syndrome (DS) is caused in most cases by the presence of an extra chromosome 21. It has been shown that the DS phenotype is produced by duplication of only a small part of the long arm of chromosome 21, the 21q22 region, including and distal to locus D21S55. We present molecular investigations on a woman with clinically typical DS but apparently normal chromosomes. Her parents were consanguineous and she had a sister with a DS phenotype, who died at the age of 15 days. Repeated cytogenetic investigations (G-banding and high resolution banding) on the patient and her parents showed apparently normal chromosomes. Autoradiographs of quantitative Southern blots of DNAs from the patient, her parents, trisomy 21 patients, and normal controls were analyzed after hybridization with unique DNA sequences regionally mapped on chromosome 21. Sequences D21S59, D21S1, D21S11, D21S8, D21S17, D21S55, ERG, D21S15, D21S112, and COL6A1 were all found in two copies. Fluorescent in situ hybridization with a chromosome 21-specific genomic library showed no abnormalities and only two copies of chromosome 21 were detected. Nineteen markers from the critical region studied with polymerase chain reaction amplification of di- and tetranucleotide repeats did not indicate any partial trisomy 21. From this study we conclude that the patient does not have any partial submicroscopic trisomy for any segment of chromosome 21. It seems reasonable to assume that she suffers from an autosomal recessive disorder which is phenotypically indistinguishable from DS.
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PMID:Molecular analysis of chromosome 21 in a patient with a phenotype of Down syndrome and apparently normal karyotype. 882 36

Exon trapping was used to identify fragments of genes on human chromosome 21. One trapped sequence, hmc 18h10 (GenBank no. X88329), showed homology to a sequence (GenBank no. S65225) that includes the first three codons of the rat PEP-19 gene and 5' untranslated leader region. We have cloned the corresponding cDNA for a human homolog of the rat PEP-19 gene and mapped it to the region between markers ERG and D21S56 of chromosome 21q22.2-q22.3. Rat PEP-19 is a neuron-specific polypeptide expressed in several regions of the central nervous system. It serves as a cell-specific marker in Purkinje cells and its expression is developmentally regulated in the cerebellum, but its precise function is unknown. It is also presently unknown whether overexpression of the PEP-19 gene is involved in certain phenotypes of Down syndrome.
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PMID:Cloning of the cDNA for a human homolog of the rat PEP-19 gene and mapping to chromosome 21q22.2-q22.3. 893 98

To identify genes that map on human chromosome 21 (HC21) and that may contribute to the phenotype of Down syndrome (DS), exon trapping was applied to cosmid DNA from an HC21-specific library LL21NCO2-Q. More than 550 potential exons were cloned and partially characterized. One of these, hmc23b04 (GenBank X88270) showed strong homology to the Drosophila Enhancer of zeste protein (GenBank U00180) from amino acid 665 to 694 (p = 7.6 x 10(-11). We have cloned the full-length cDNA for this human homolog of the Drosophila E(z) gene (termed EZH2) and mapped it to within YACs 64f11 and 809b11 between markers D21S65 and ERG on human chromosome 21q22.2. Sequence analysis indicates that EZH2 encodes a 746-amino-acid polypeptide that shows 60.5% identity to the Drosophila E(z) protein and contains a trithorax-like domain and a DNA-binding motif. Northern blot analysis revealed that EZH2 is expressed in several tissues. Alternatively spliced mRNA species have been observed. The Drosophila E(z) protein is a member of the polycomb group genes that maintain homeotic gene repression and are thought to control gene expression by regulating chromatin. The strong sequence conservation suggests a possible function of EZH2 in regulation of gene transcription and chromatin structure; it may therefore contribute to certain phenotypes of Down syndrome by altered regulation of its target genes.
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PMID:Cloning of a human homolog of the Drosophila enhancer of zeste gene (EZH2) that maps to chromosome 21q22.2. 895 76

The Down syndrome (DS) region has been defined by analyses of partial trisomy 21. The 2.5-Mb region between D21S17 and ERG is reportedly responsible for the main features of DS. Within this 2.5-Mb region, we focused previously on a distal 1.6-Mb region from an analysis of Japanese DS patients with partial trisomy 21. Previously we also performed exon-trapping and direct cDNA library screening of a fetal brain cDNA library and identified a novel gene TPRD. Further screening of a fetal heart cDNA library was performed and a total of 44 possible exons and 97 cDNA clones were obtained and mapped on a BamH1 map. By rescreening other cDNA libraries and a RACE reaction, we isolated nearly full-length cDNAs of three additional genes [holocarboxylase synthetase (HCS), G protein-coupled inward rectifier potassium channel 2 (GIRK2), and a human homolog of Drosophila minibrain gene (MNB)] and a coding sequence of a novel inward rectifier potassium channel-like gene (IRKK). The gene distribution and direction of transcription were determined by mapping both ends of the cDNA sequences. We found that these genes, except IRKK, are expressed ubiquitously and are relatively large, extending from 100 kb to 300 kb on the genome. These nearly full-length cDNA sequences should facilitate understanding of the detailed genome structure of the DS region and help to elucidate their role in the etiology of DS.
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PMID:Gene identification in 1.6-Mb region of the Down syndrome region on chromosome 21. 903 1

Exon trapping was used to identify portions of human chromosome 21-encoded genes. More than 600 potential exons on the chromosome have been cloned and characterised to date. A BLAST search of databases revealed that three of these trapped "exons", hmc18a08, hmc18f10 and hmc27g09, showed strong homology to different regions of the Drosophila mnb (Genbank X70794) and rat Dyrk (Genbank X79769) genes, indicating that these three exons may be portions of a human homologue of these genes (we termed this gene MNB for minibrain). With amplification by the polymerase chain reaction and hybridisation analysis we have mapped the human MNB gene on overlapping yeast artificial chromosomes 336G11 and 806A11 of chromosome 21q22.2 between markers D21S65 and ERG. The Drosophila mnb (minibrain) gene, which encodes a member of the protein kinase family, is involved in postembryonic neurogenesis. The Dyrk gene, which encodes a dual specificity protein kinase, is a rat homologue of the Drosophila mnb gene. The kinase activity is dependent on tyrosine residues in the catalytic domain, and it has been speculated that the protein is involved in control of the cell cycle. Altered expression of the human MNB gene may be involved in the pathogenesis of certain phenotypes of Down syndrome, including mental retardation.
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PMID:Localisation of a human homologue of the Drosophila mnb and rat Dyrk genes to chromosome 21q22.2. 904 32


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