SEQUENCE-ANALYSIS AND CHARACTERIZATION OF STUTTER PRODUCTS AT THE TETRANUCLEOTIDE REPEAT LOCUS VWA

The PCR amplification of tetranucleotide short tandem repeat (STR) loc i typically produces a minor product band 4 bp shorter than the corres ponding main allele band; this is referred to as the stutter band, Seq uence analysis of the main and stutter bands for two sample alleles of the STR locus vWA reveals that the stutter band lacks one repeat unit relative to the main allele, Sequencing results also indicate that th e number and location of the different 4 bp repeat units vary between samples containing a typical verses low proportion of stutter product. The results also suggest that the proportion of stutter product relat ive to the main allele increases as the number of uninterrupted core r epeat units increases. The sequence analysis and results obtained usin g various DNA polymerases appear to support the slipped strand displac ement model as a potential explanation for how these stutter products are generated.