IN-SITU DETECTION OF TANDEM DNA REPEAT LENGTH

A simple method for scoring short tandem DNA repeats is presented. An oligonucleotide target, containing tandem repeats embedded in a unique sequence, was hybridized to a set of complementary probes, containing tandem repeals of known lengths. Single-stranded loop structures form ed on duplexes containing a mismatched (different) number of tandem re peals. No loop structure formed on duplexes containing a matched (iden tical) number of tandem repeats. The matched and mismatched loop struc tures were enzymatically distinguished and differentially labeled by t reatment with Sl nuclease and the Klenow fragment of DNA polymerase. C opyright (C) 1996 Elsevier Science B.V.