Comparison of type and frequency of chromosome aberrations by conventional and G-staining methods in Hiroshima atomic bomb survivors.

Abstract

Somatic chromosomes derived from lymphocytes of 23 Hiroshima A-bomb survivors were analyzed to determine the type and frequency of radiation-induced chromosome aberrations, using the ordinary staining method (O-method) and the trypsin G-banding method (G-method). Of 896 cells examined, 342 had aberrations, including 31 unidentifiable cells even by the G-method. The number of aberrations detected was 376 in 311 cells. The majority of them were intra- or inter-chromosomal symmetric exchanges, while only 24 were asymmetric exchanges (dicentrics, rings and interstitial deletions). Aberrations included acentric fragments and terminal deletions, and the remaining 36 were complex intra- and inter-chromosomal exchanges showing insertions and double translocations. An analysis of the same metaphases examined by sequential O- and G-methods was carried out independently on 361 aberrations. It was found that 78 were detectable only by the G-method; among these were 14 paracentric inversions, 48 reciprocal interchanges of chromosome segments with equal or unequal length, 14 minor deletions and 2 complex rearrangements, all of which were judged as the normal variation by the O-method. Aberrations (25) detected by the O-method showed normal banding patterns by the G-method.