抄録
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 both the ordinary staining method (0-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 found to be asymmetric exchanges (dicentrics, rings and interstitial deletions). Further, 28 aberrations included acentric fragments and terminal deletions, and the remaining 36 were complex intraand inter-chromosomal exchanges showing insertions and double translocations.
An analysis of the same metaphases examined by sequential 0 and G-methods was carried out independently on 361 aberrations. It was found that 78 were detectable only by the Gmethod; among these were 14 paracentric inversions, 48 reciprocal interchanges of chromosome segments with either equal or unequal length, 14 minor deletions and 2 complex rearrangements, all of which were judged as the normal variation by the O-method. In contrast, 25 aberrations detected by the 0-method were found to show normal banding patterns by the G-method.
