Abstract: BACKGROUND AND AIM: In 1990, 2 severe and 3 moderate degree acute radiation syndrome (ARS) victims in Shanghai “6.25” 60Co accident were cured. To investigate late effects of ARS, 14 years continuous follow-up study of chromosomal aberrations in these 5 victims was performed to accumulate valuable data on late effect of radiation. MATERIALS AND METHODS: Conventional chromosome aberration, G-banding automatic karyotype analysis and whole chromosome probe painting FISH technique were used simultaneously to examine unstable and stable chromosome aberrations and compare the results over 14 years. RESULTS: Unstable aberrations declined to approximately 20％ of initial level 3.5 years after exposure and was totally lost after 14 years. Stable aberrations such as reciprocal translocations were found predominantly. The results of G-banding karyotype analysis and FISH were very similar. The frequencies of Cs and complicated aberrations showed a dose-response relationship and remained at a relatively stable level 6－14 years after exposure. The break frequencies of each chromosome distributed randomly. The recovery speed of chromosome aberrations and degree of late effect related not only to exposure dose but also to the victims＇ health condition. CONCLUSION: Stable chromosome aberrations were fairly ideal in the assessment of radiation late effects. It is important to make long-term follow-up study for the victims exposed to accidental irradiation.

Key words: chromosomal aberrations, G-banded karyotype analysis, FISH, radiation late effects