title: Distribution of radiation-induced exchange aberrations in human chromosomes 1, 2 and 4.
abstract: OBJECTIVE
  To examine the distribution of radiation-induced breakpoints in chromosomes 1, 2 and 4 both in relation to their DNA content and by localization of the breaks along each chromosome.
  
  
  METHODS
  The work consisted of two studies, one with chromosomal aberrations found in persons after accidental exposure in Estonia in 1994 and another involving aberrations seen in in vitro-irradiated lymphocytes. Localization of breakpoints in painted chromosomes involved in complete exchange-type aberrations was conducted by applying a computerized measuring system on stored image-files.
  
  
  CONCLUSIONS
  The yield of exchanges in chromosomes 1, 2 and 4 in both studies was equal to that expected from their DNA content. In contrast, the breakpoint location of complete exchanges within these chromosomes was not random. Chromosomes 1 and 4 contained more breaks in the middle parts of the p and q arms, whereas breaks were observed more uniformly along chromosome 2. Complete exchanges, however, were very rare in the terminal regions of all three chromosomes, most probably resulting from limitations in the resolution of small painted pieces.
authors.affiliation: Research and Environment, Radiation and Nuclear Safety Authority (STUK), Helsinki, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Luomahaara
authors.forename: C
authors.initials: C
authors.lastname: Lindholm
authors.forename: R
authors.initials: R
authors.lastname: Mustonen
authors.forename: S
authors.initials: S
authors.lastname: Salomaa
mesh_terms: D018929:Cell Culture Techniques; D002869:Chromosome Aberrations; D019457:Chromosome Breakage; D020223:Chromosome Painting; D002877:Chromosomes, Human / Q000528:radiation effects*; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics / Q000528:radiation effects; D002889:Chromosomes, Human, Pair 2 / Q000235:genetics / Q000528:radiation effects; D002894:Chromosomes, Human, Pair 4 / Q000235:genetics / Q000528:radiation effects; D004247:DNA / Q000235:genetics / Q000528:radiation effects; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008214:Lymphocytes / Q000528:radiation effects / Q000648:ultrastructure; D008677:Metaphase; D018788:Radioactive Hazard Release
chemical_list: D004247:DNA