Large deletions partially external to the human hprt gene result in chimeric transcripts.

We postulated that gene fusions sometimes occur in normal cells as a result of gene rearrangements as have been observed involving oncogene loci in tumours. To test this, we searched for fusion-gene transcripts in selected human T-lymphocyte large deletion mutations of the hypoxanthine-guanine phosphoribosyltransferase (hprt) gene using the 3' rapid amplification of cDNA ends (RACE) technique. Aberrant hprt-containing transcripts were observed in seven out of 19 mutants (approximately 36%) indicating that a surprising number of these rearrangements code for processed mRNAs. RNA splicing and polyadenylation occurred downstream of the non-deleted hprt sequence in chimeric transcripts and the majority resulted from mutants with fusions of hprt into regions containing a repetitive element (Alu, LINE or microsatellite).