title: Relative involvement of chromosome #21 in radiation induced exchange aberrations in lymphocytes of Down syndrome patients.
abstract: It is not yet resolved as to what type of DNA double strand break repair operates in G0 lymphocytes. We have employed Down syndrome (DS) lymphocytes with three copies of chromosome #21 to answer the question whether the presence of three copies reduces the frequency of exchange aberrations involving this chromosome in comparison to normal cells with two copies of #21. Peripheral blood lymphocytes from three DS patients and two normal individuals were X-irradiated with 1 and 3 Gy. The frequencies of unstable aberrations were found to be higher in DS lymphocytes than normal lymphocytes after 3 Gy of X-rays. FISH studies employing chromosome specific DNA libraries for chromosomes #21 and #22 indicated that the frequencies of exchange aberrations per chromosome are similar in both disomic and trisomic condition. This indicates that the presence of an extra copy of chromosome #21 does not alter the yield, suggesting that homologous recombination does not play a major role in the repair of DNA strand breaks in human G0 lymphocytes.
authors.affiliation: Department of Radiation Genetics and Chemical Mutagenesis, Leiden University, Wassenaarseweg 72, 2333 AL Leiden, Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Grigorova
authors.forename: A T
authors.initials: AT
authors.lastname: Natarajan
mesh_terms: D002869:Chromosome Aberrations / Q000235:genetics; D002875:Chromosomes / Q000528:radiation effects; D002891:Chromosomes, Human, Pair 21 / Q000528:radiation effects*; D015342:DNA Probes / Q000235:genetics; D004260:DNA Repair / Q000235:genetics; D004314:Down Syndrome / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007399:Interphase / Q000502:physiology; D008214:Lymphocytes / Q000528:radiation effects*; D011995:Recombination, Genetic / Q000235:genetics; D014965:X-Rays
chemical_list: D015342:DNA Probes