Regional mapping of human genes for hexosaminidase B and diphtheria toxin sensitivity on chromosome 5 using mouse X human hybrid cells.

Mouse 3T3 (TK-) cells were fused to human leukocytes containing a balanced translocation [ins(3;5) (q27;q13q15)] in which part of the long arm of a chromosome 5 has been inserted into the long arm of a chromosome 3. Two independent, primary hybrid clones (XVI-10C;XVI-18A) retained the deleted chromosome 5 [del(5) (q13q15)] translocation product and were informative for regional mapping on chromosome 5 of genes involved in expression of hexosaminidase B (HEXB) and diphtheria toxin sensitivity (DTS). Both XVI-10C and XVI-18A clones were sensitive to diphtheria toxin. Toxin-resistant derivatives of these clones (XVI-10C DTR; XVI-18A DTR) were analyzed for chromosome content and expression of Hex B activity, as were XVI-10C and XVI-18A cells which had not been exposed to diphtheria toxin. The results of this study provide evidence for localization of DTS to region 5q15 leads to 5 qter on the long arm of chromosome 5, and localization of HEXB to region 5pter leads to 5q13.