Chromosomal aberrations in irradiated Down's syndrome fibroblasts.

We have compared the frequencies of chromosomal aberrations in skin fibroblasts from persons with Down's syndrome (trisomy 21) with those from normal diploid controls exposed to 60Co gamma-radiation in vitro. No difference between the chromosomal radiosensitivities of the two groups was observed, nor did the two groups differ in the background frequency of spontaneous aberrations. These data support the hypothesis that the increased in vitro chromosomal radiosensitivity of lymphocytes reported to be associated with trisomy 21 is not typical of all tissues.