ADDITIONAL ASSIGNMENT OF THE HUMAN 5S RIBOSOMAL-RNA GENES TO CHROMOSOME REGION 1Q31

A major fraction of the human 5S rRNA genes has previously been assign ed to chromosome region 1q42.11 --> q42.13 (Sorensen et al., 1991). Th rough in situ hybridization of different tritiated probes to metaphase spreads, we have demonstrated that a minor fraction of the 5S rRNA ge nes is localized at band 1q31. This fraction amounts to 25-30% of the genes found in the region 1q42.11 --> q42.13. Results obtained with th e chromosomes of a balanced translocation carrier involving this regio n indicate that the major cluster is localized in band 1q42.13.