Synthesis of long trinucleotide repeats in vitro.

More than a dozen diseases have been associated with the expansion of trinucleotide repeats. Most of these expanding repeats are GC-rich (CGG/CCG or CTG/CAG), but it is difficult to amplify GC-rich repeat DNA from patient samples by the polymerase chain reaction. We invented a pair of methods to synthesize long trinucleotide repeats in vitro by polymerase extension utilizing a thermal cycler. A combination of the two methods, termed the non-template PCR method and SLIP (Synthesis of Long Iterative Polynucleotide) method, produced (CTG/CAG)190 repeat DNA. We expect that these two methods will contribute to studies of all diseases associated with tri-nucleotide repeat expansion, since they can be applied to any type of repeat DNA.