Direct cloning of human transcripts with HnRNA from hybrid cell lines.

A library of human-derived complementary DNA from a human-hamster hybrid cell line containing the Xq24-qter region has been constructed. Complementary DNA synthesis was primed from heterogeneous nuclear (hn) RNA by oligonucleotides derived from conserved regions of human Alu repeats. At least 80% of these cloned sequences were of human origin, providing an enrichment of at least two orders of magnitude. Two clones, one containing a fragment of the primary transcript of the human hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene at Xq26 and another recognizing a family of human genes mapping to two regions of Xq24-qter, were characterized. Additional hncDNA clones mapped to a variety of sites in the Xq24-qter region, demonstrating the isolation of many transcriptionally active loci. These clones provide probes for identification of genetic loci on the terminal region of the X chromosome long arm, which is the location of a number of inherited disorders.