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: Comparative genomics is beginning to identify the functional components of the chromosome and that in turn will set the stage for the functional characterization of the sequences.
Abstract: The sequence of chromosome 21 was a turning point for the understanding of Down syndrome. Comparative genomics is beginning to identify the functional components of the chromosome and that in turn will set the stage for the functional characterization of the sequences. Animal models combined with genome-wide analytical methods have proved indispensable for unravelling the mysteries of gene dosage imbalance.
613 citations
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TL;DR: This study shows that flow sorting of aberrant chromosomes and chromosome painting can be used as a rapid aid to cytogenetic analysis, particularly in cases of difficult karyotypes, such as tumours.
Abstract: A novel polymerase chain reaction (PCR) technique has been combined with chromosome flow sorting to characterise two lymphoblastoid cell lines and one medullary thyroid carcinoma cell line carrying translocations close to the locus for multiple endocrine neoplasia type 2A (MEN 2A). Five hundred copies of the derivative chromosome(s) were flow sorted from each cell line and amplified by degenerate oligonucleotide-primed-polymerase chain reaction (DOP-PCR). This generated pools of DNA sequences corresponding to the abnormal chromosomes, which were then used as probes in fluorescence in situ hybridisation (FISH) experiments on normal metaphase cells. The resultant chromosome paints revealed the portions of the normal chromosomes related to those involved in the translocations. By this technique, translocation breakpoints in bands p15, q11.2, and q21 of chromosome 10 were defined in the above cell lines, in two cases refining previous cytogenetic data. This study shows that flow sorting of aberrant chromosomes and chromosome painting can be used as a rapid aid to cytogenetic analysis, particularly in cases of difficult karyotypes, such as tumours. Furthermore, the DOP-PCR technique described here will have applications to other areas of genome analysis, such as cloning of new markers; its design will allow a general and representative amplification to occur from any starting DNA in any species.
584 citations
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TL;DR: This finding links genome organization with chromosome structure and function with the exception of some telomeric regions, and the chromosomal regions of simple sequence DNA, Alu and L1 are precisely inversely distributed, suggesting an inverse functional relationship.
563 citations
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TL;DR: Recent work with yeast, Xenopus, and other model systems has provided new information about the proteins that control chromosome segregation during cell division and how the activities of these proteins are coordinated with the cell cycle.
Abstract: During cell division, each daughter cell inherits one copy of every chromosome. Accurate transmission of chromosomes requires that the sister DNA molecules created during DNA replication are disentangled and then pulled to opposite poles of the cell before division. Defects in chromosome segregation produce cells that are aneuploid (containing an abnormal number of chromosomes)-a situation that can have dire consequences. Aneuploidy is a leading cause of spontaneous miscarriages in humans and is also a hallmark of many human cancer cells. Recent work with yeast, Xenopus, and other model systems has provided new information about the proteins that control chromosome segregation during cell division and how the activities of these proteins are coordinated with the cell cycle.
560 citations
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TL;DR: This work demonstrates the use of digital PCR to determine the allelic imbalance of a SNP on PLAC4 mRNA, a placenta-expressed transcript on chromosome 21, in the maternal plasma of women bearing trisomy 21 fetuses, and developed a nonpolymorphism-based method for the noninvasive prenatal detection of trisome 21.
Abstract: Trisomy 21 is the most common reason that women opt for prenatal diagnosis. Conventional prenatal diagnostic methods involve the sampling of fetal materials by invasive procedures such as amniocentesis. Screening by ultrasonography and biochemical markers have been used to risk-stratify pregnant women before definitive invasive diagnostic procedures. However, these screening methods generally target epiphenomena, such as nuchal translucency, associated with trisomy 21. It would be ideal if noninvasive genetic methods were available for the direct detection of the core pathology of trisomy 21. Here we outline an approach using digital PCR for the noninvasive detection of fetal trisomy 21 by analysis of fetal nucleic acids in maternal plasma. First, we demonstrate the use of digital PCR to determine the allelic imbalance of a SNP on PLAC4 mRNA, a placenta-expressed transcript on chromosome 21, in the maternal plasma of women bearing trisomy 21 fetuses. We named this the digital RNA SNP strategy. Second, we developed a nonpolymorphism-based method for the noninvasive prenatal detection of trisomy 21. We named this the digital relative chromosome dosage (RCD) method. Digital RCD involves the direct assessment of whether the total copy number of chromosome 21 in a sample containing fetal DNA is overrepresented with respect to a reference chromosome. Even without elaborate instrumentation, digital RCD allows the detection of trisomy 21 in samples containing 25% fetal DNA. We applied the sequential probability ratio test to interpret the digital PCR data. Computer simulation and empirical validation confirmed the high accuracy of the disease classification algorithm.
558 citations