I am working on Amyotrophic lateral sclerosis and try to amplify the GGGGCC hexanucleotide repeat expansion on Chromosome 9 (C9ORF72). I amplified it with FAM labelled primers by repeat primed PCR and ran the product on sequencer, but I did not get exactly six nucleotide differences between peaks. I also have done normal PCR with outer primers and got smaller sized products. Please help me out if anyone is working with repeat primed PCR Thanks.