Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chromosome imbalance (aneusomy) is the leading known cause of both spontaneous abortion and mental retardation in human beings. The primary abnormality is thought to result from quantitative changes of transcription products from the unbalanced genetic material. To document this point, I compared chromosome 21-specific transcription in skin fibroblasts from subjects with monosomy 21, disomy 21 (normal), and trisomy 21 (Down syndrome). Polyadenylylated RNA [poly(A)-RNA], which is enriched in messenger and messenger-precursor RNA sequences, was isolated from the above fibroblast lines. Radioactive DNA (cDNA) complementary to these RNAs was synthesized with reverse transcriptase (RNA-dependent DNA polymerase). These cDNAs were hybridized with (i) DNA from a cell line with a mouse genome plus human chromosome 21 and (ii) mouse DNA. Subtraction of the amount of hybridization in experiment ii from that in experiment i yielded a measure of human chromosome 21-specific RNA sequences. The results were consistent with gene dosage at the transcriptional level; for monosomy 21-derived cDNA, 0.6% (of the total cDNA) hybridized specifically to human chromosome 21; for disomy 21-derived cDNA, 2% hybridized; and for trisomy 21-derived cDNA, 3% hybridized. Thus, for DNA sequences on chromosome 21 in human skin fibroblasts, transcription depends on DNA dosage. Characterization of the chromosome 21-specific RNA sequences quantitated in these experiments could help to elucidate the mechanisms by which abnormal karyotypes result in abnormal phenotypes.
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PMID:Down syndrome: gene dosage at the transcriptional level in skin fibroblasts. 15 66

Variants of the t(8;21)(q22;q22) involving chromosome 8, 21, and other chromosomes account for approximately 3% of all t(8;21)(q22;q22) found in patients with acute myeloid leukemia (AML). The clinicopathologic features of AML with the variant t(8;21) have not been well established. We report three cases of AML with variants of t(8;21) characterized, respectively, by derivative 8 with the interstitial inverted insertion of 21q and concurrent monosomy 21, t(8;18;21)(p22;q11.3;q22), and t(2;21;8)(q11.2;q22;q22). Fluorescence in situ hybridization or reverse transcriptase-polymerase chain reaction assay confirmed the presence of RUNX1-RUNX1T1 gene (previously AML1-ETO) rearrangements. Among these cases, three-way breakpoints 18p11.3 and 2q11.2 have not been previously reported. The present report deals with the results of hematologic, immunophenotypic, cytogenetic, fluorescence in situ hybridization, and molecular analyses of these variants. The possible role of the genes in this region in leukemogenesis, response to treatment, and clinical implications are discussed.
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PMID:Acute myeloid leukemia (AML-M2) associated with variant t(8;21): report of three cases. 2041 66