Topic
Chromosome 21
About: Chromosome 21 is a research topic. Over the lifetime, 4736 publications have been published within this topic receiving 206655 citations. The topic is also known as: chr21 & Homo sapiens chromosome 21.
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TL;DR: It is suggested, that CISS hybridization can be expected to become an indispensable tool in comparative chromosome and gene mapping and will help clarify chromosomal phylogenies with speed and accuracy.
Abstract: We established chromosomal homologies between all chromosomes of the human karyotype and that of an old world monkey (Macaca fuscata) by chromosomal in situ suppression (CISS) hybridization with human chromosome specific DNA libraries. Except for the human chromosome 2 library and limited cross-hybridization of X and Y chromosome libraries all human DNA libraries hybridized to single GTG-banded macaque chromosomes. Only three macaque chromosomes (2, 7, 13) were each hybridized by two separate human libraries (7 and 21, 14 and 15, 20 and 22 respectively). Thus, an unequivocally high degree of synteny between human and macaque chromosomes has been maintained for more than 20 million years. As previously suggested, both Papionini (macaques, baboons, mandrills and cercocebus monkeys, all of which have nearly identical karyotypes) and humans are chromosomally conservative. The results suggest, that CISS hybridization can be expected to become an indispensable tool in comparative chromosome and gene mapping and will help clarify chromosomal phylogenies with speed and accuracy.
183 citations
TL;DR: A few examples of how trisomy for specific genes affects the development of the cortex and cerebellum are provided to illustrate how gene dosage effects might contribute to divergence between the trisomic and euploid brains.
183 citations
TL;DR: Given the results, which in some patients were in disagreement with their cytogenetic descriptions, trisomy for locus D21S13 through locusD21S58 is excluded from significant contribution to many Down syndrome features, the minimal chromosome region necessary in triplicate to result in the Down syndrome phenotypes in the patients characterized.
182 citations
01 Jan 1996
TL;DR: It is found that two myeloid leukemia cell lines with the t(8;21) translocation, Kasumi and SKNO-1, have elevated levels of BCL-2 protein compared with other myeloids cell lines, and a consensus AML1 binding site is identified in the B CL-2 promoter.
Abstract: The AML1 gene, located on chromosome 21, is involved in several distinct chromosomal translocations in human leukemia. In t(8;21) acute myelogenous leukemia (AML),theAML1geneisjuxtaposedtotheETOgenelocated on chromosome 8, generating an AML1yETO fusion protein. BothAML1yETOandtheAML1proteinsrecognizethesame consensus DNA-binding motif (TGTyCGGT), which is found in the promoters of several genes involved in hematopoiesis. Wefoundthattwomyeloidleukemiacelllineswiththet(8;21) translocation, Kasumi and SKNO-1, have elevated levels of BCL-2 protein compared with other myeloid cell lines. In addition, we identified a consensus AML1 binding site in the BCL-2 promoter. Thus far, AML1yETO has been shown to dominantly repress its target genes; however, we found that AML1yETOactivatestranscriptionoftheBCL-2geneinU937 cells. This activation requires the presence of both the runt homologydomain(rhd)andtheC-terminalportionofAML1y ETO. We demonstrated sequence specific binding of both AML1A and AML1yETO to the TGTGGT sequence in the BCL-2 promoter and showed that the AML1 binding site is required for responsiveness to AML1yETO. Interestingly, AML1AandAML1BdonotmodulatetheactivityoftheBCL-2 promoter. The elevated levels of BCL-2 in cells that express AML1yETOmayprolongtheirlifespanandcontributetothe development of t(8;21) leukemia.
182 citations
TL;DR: Using a comparative genomic approach, this work has been able to locate precisely the translocation breakpoint in these two models and took advantage of this finding to derive a new and more efficient Ts65Dn genotyping strategy.
Abstract: Down syndrome (DS) is the most frequent genetic disorder leading to intellectual disabilities and is caused by three copies of human chromosome 21. Mouse models are widely used to better understand the physiopathology in DS or to test new therapeutic approaches. The older and the most widely used mouse models are the trisomic Ts65Dn and the Ts1Cje mice. They display deficits similar to those observed in DS people, such as those in behavior and cognition or in neuronal abnormalities. The Ts65Dn model is currently used for further therapeutic assessment of candidate drugs. In both models, the trisomy was induced by reciprocal chromosomal translocations that were not further characterized. Using a comparative genomic approach, we have been able to locate precisely the translocation breakpoint in these two models and we took advantage of this finding to derive a new and more efficient Ts65Dn genotyping strategy. Furthermore, we found that the translocations introduce additional aneuploidy in both models, with a monosomy of seven genes in the most telomeric part of mouse chromosome 12 in the Ts1Cje and a trisomy of 60 centromeric genes on mouse chromosome 17 in the Ts65Dn. Finally, we report here the overexpression of the newly found aneuploid genes in the Ts65Dn heart and we discuss their potential impact on the validity of the DS model.
181 citations