Cytogenetic studies on bone marrow cells of the atomic bomb survivors in Nagasaki

A study was made of chromosomes of bone marrow cells in 30 atomic bomb survivors, consisting of 9 cases exposed to atomic bomb within 1000 m from the bombed area in Group I, 11 cases exposed at a distance of 1001-2500 m from that place in Group II, and 10 cases exposed more than 2500 from that place in Group III. They ranged in age from 47 to 92 years (average age 74.5 years). Chromosome count was 46 in all cases. The average of modality percentage was 92.5% in Group I, 94.2% in Group 2, and 91.6% in Group 3, showing that there was no significant difference among these groups. From the standpoint of frequency of chromosome aberation, no hyperdiploid cells of the aneuploid cells were observed in any case, but hypodiploid cells were observed in about 6% of each group. Therefore, there was no significant difference among them. Among 82 hypodiploid cells, 44 abnormal chromosomes were observed in G or Y. This abnormality was obtained in 2 cases of Group 1, and 1 case of Group 3. All cases were old males aged 77, 82 and 92 years, respectively. Although the loss of chromosomes in C was seen in 1 female in Group 2, the chromosometic type was unknown. In other chromosome abnormalities, unstable abnormal cells were observed in one case of Group III, and stable abnormal cells in 2 cases of Group I. Each abnormality was seen in only one cell. There was no case in which more than two cells having the same stable chromosome abnormality were observed in one case. These results showed that the frequency of chromosome abnormality was low in all cases, showing that there was no significant difference among them. (Kanao, N.)