Isolation of a polymorphic DNA segment unique to human chromosome 7 by molecular cloning of hybrid cell DNA

DNA isolated from a rodent-human hybrid cell line containing human chromosomes 3, 7, 9, 10, 14 and 22 was cloned in the plasmid vector pAT153. Recombinant plasmids containing inserts of human origin were identified by colony hybridization to 32P-labelled human DNA under conditions in which only repetitive sequences interact. Single- and low-copy sequences were liberated from these plasmids by restriction endonuclease digestion and used as hybridization probes against human DNA and DNA isolated from a panel of Chinese hamster-human hybrids. One single-copy probe was shown to react with a genomic sequence unique to human chromosome 7 and to recognize an apparent restriction fragment size polymorphism in human DNA.