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.

Multiple regions of chromosome 6q affected by loss of heterozygosity in primary human breast carcinomas.

Abstract: A total of 80 primary human breast carcinoma DNAs were analysed for loss of heterozygosity (LOH) on the long arm of chromosome 6, using microsatellite markers whose location has been defined physically and by linkage analysis. Loss of heterozygosity was observed in 38 of 80 (48%) tumours that were informative for at least one locus. The analysis revealed partial or interstitial deletions of chromosome 6q. Detailed mapping of chromosome 6q in these tumour DNAs identified two and perhaps three commonly deleted regions. One of these is located between markers D6S251 and D6S252 (6q14-q16.2), another between D6S268 and D6S261 (6q16.3-q23) and a third between D6S287 and D6S270 (6q22.3-q23.1).

Physical localization of the flocculation gene FLO1 on chromosome I of Saccharomyces cerevisiae.

Abstract: The genetics of flocculation in the yeast Saccharomyces cerevisiae are poorly understood despite the importance of this property for strains used in industry. To be able to study the regulation of flocculation in yeast, one of the genes involved, FLO1, has been partially cloned. The identity of the gene was confirmed by the non-flocculent phenotype of cells in which the C-terminal part of the gene had been replaced by the URA3 gene. Southern blots and genetic crosses showed that the URA3 gene had integrated at the expected position on chromosome I. A region of approximately 2 kb in the middle of the FLO1 gene was consistently deleted during propagation in Escherichia coli and could not be isolated. Plasmids containing the incomplete gene, however, were still able to cause weak flocculation in a non-flocculent strain. The 3' end of the FLO1 gene was localized at approximately 24 kb from the right end of chromosome I, 20 kb centromere-proximal to PHO11. Most of the newly isolated chromosome I sequences also hybridized to chromosome VIII DNA, thus extending the homology between the right end of chromosome I and chromosome VIII to approximately 28 kb.

Differentially amplified chromosome 12 sequences in low- and high-grade osteosarcoma.

Abstract: Most osteosarcomas are highly aggressive malignancies characterized by a complex pattern of chromosome abnormalities. However, a subgroup of low-grade, parosteal tumors exhibits a relatively simple aberration pattern dominated by ring chromosomes carrying amplified material from chromosome 12. To assess whether sequences from this chromosome were differentially amplified in low- and high-grade osteosarcomas, copy numbers of the CCND2, ETV6, KRAS2, and D12S85 regions in 12p and the MDM2 region in 12q were evaluated by interphase or metaphase fluorescence in situ hybridization (FISH) in 24 osteosarcomas. Amplification of MDM2 was detected in all five low-grade and four high-grade osteosarcomas, all of which showed ring chromosomes. An overrepresentation of 12p sequences was found in 1/5 low-grade and in 9/19 high-grade tumors. Multicolor single-copy FISH analysis of metaphase cells from six high-grade tumors showed that extra 12p material either occurred together with MDM2 in ring chromosomes or was scattered over the genome as a result of complex structural rearrangements. Most tumors (8/10) not containing amplification of the assessed chromosome 12 loci exhibited a nondiploid pattern at evaluation with probes for centromeric alpha satellite sequences. These findings indicate that gain of sequences from the short arm of chromosome 12 could be a possible genetic pathway in the development of aggressive osteosarcoma.

Isolation, characterization, and chromosomal localization of human brain cDNA clones coding for the precursor of the amyloid of brain in Alzheimer's disease, Down's syndrome and aging.

Abstract: Four clones have been isolated from the adult human brain cDNA library using an oligonucleotide probe corresponding to the first 20 amino acids of the brain amyloid polypeptide. The open reading frame of the sequenced clone coded for the known full amino acid sequence of the brain amyloid polypeptide. The 3 kb messenger RNA has been detected in a variety of tissues from human and many nonhuman species. The gene is highly conserved in evolution and has been mapped on human chromosome 21.