ANEUPLOIDY IN SOMATIC-CELLS OF IN-UTERO EXPOSED A-BOMB SURVIVORS IN HIROSHIMA

Cytogenetic data on cultured lymphocytes of the in utero exposed A-bom b survivors in the RERF Adult Health Study cohort have been analyzed u sing the G-banding technique to determine the frequency of aneuploid c ells. The data consist of blood samples collected between 1985 and 198 7 from 264 Hiroshima individuals for whom DS86 maternal uterine dose e stimates are available: 124 proximally exposed (74 males and 50 female s) with an estimated dose of 0.005 Sv or more, and 140 distally expose d (76 males and 64 females) with a dose estimate of 0 Sv, assuming the neutron relative biological effectiveness (RBE) of 10. A main feature of aneuploidy was that aneuploid frequency in autosomes depended gene rally on chromosome length; aneuploidies were significantly more frequ ent in shorter chromosomes than in longer chromosomes. The frequency o f aneuploidies also depended on type, with chromosome loss approximate ly five times more frequent than chromosome gain. However, chromosome 21, as well as the sex chromosomes, were notable in that aneuploidy wa s much more frequent for these chromosomes than would be predicted fro m a simple relationship with length. X chromosome aneuploidies were si gnificantly more frequent in females than in males. There was no depen dence of aneuploid frequencies on dose when measured 40 years after th e exposure.