[Incidence of the qh+ varients in the karyotype of subjects occupationally exposed to ionizing radiations].

The "qh+" variants in the human karyotype are generally held to be inherited and devoid of phenotypical effects, although more frequent in families with cases of chromosomal aberrations. The finding of an even higher frequency of apparent mosaicism for 9qh+ in the karyotype of individuals professionally exposed to radiation supports the hypothesis that the variant may be mutagen-induced, possibly reflecting a "first hit" in chromosomal damage. Further studies are under way to verify the hypothesis, in view of a possible use as an indicator of radiation damage and/or risk factor in genetic counseling.