A Method for the Incremental Expansion of Polyglutamine Repeats in Recombinant Proteins

The polyglutamine diseases are caused by the expansion of CAG repeats. A key step in understanding the disease mechanisms, at the DNA and protein level, is the ability to produce recombinant proteins with specific length glutamine tracts which is a time-consuming first step in setting up in vitro systems to study the effects of polyglutamine expansion. Described here is a PCR-based method for the amplification of CAG repeats, which we used to incrementally extend CAG length by 3–5 repeats per cycle. This method could be translated into various contexts where amplification of repeating elements is necessary.