The pattern of radiation-induced transmissible aberrations in a human cell culture.

The G-band pattern in 445 metaphases obtained seven weeks after irradiation (600 rad gamma-ray) was analysed. Approximately 37% of these cells had one or more structural aberrations. The majority of the aberrant events was reciprocal translocation followed by inversion and deletion in the proportion of 9:1:1 respectively. Statistical analyses (Chi-square tests) on the distribution of breakpoints among chromosomes showed an excess number of breaks in chromosomes 1, 7, and 12. Chromosomes 1 and 12 were particularly involved in cells carrying multiple aberrations while chromosome 7 was preferentially involved in deletion. Within chromosomes a significantly large number of breaks were located in (a) the light bands and (b) the terminal segments. The significance of these findings is discussed.