3.3. Specificity of the dipstick assay
In order to confirmthat each extended primer hybridizes only to the
corresponding capture probe on the membrane and not to any other
immobilized probes, we performed the following experiment: two
samples, one normal and the second synthetic mutant for allmutations,
were subjected to two PEXT reactions, one in the presence of normal
primers and the second in the presence of mutant primers. The synthetic
sample was prepared bymixing equal amounts of PCR products from
samples that contained at least one of the mutations. Therefore, the
synthetic sample represented a heterozygous template for all primers.
An example of specificity results is shown in Fig. 3A. Normal primers
are extended in the presence of both samples while mutant primers
are not extended in the presence of normal sample. Themutant primers
are extended and give signal only in the presence of mutant sample.