(b) RT-PCR analysis using the blue primer set (left) and green primer set (right) from a. Whereas control cDNA samples showed a single product corresponding to the wild-type allele (WT), an apparently longer product was observed in subjects 1, 2 and 5, indicating that only the transcripts from the mutant allele were expressed. In subject 3, both wild-type and mutant alleles were expressed. Template without reverse transcriptase was used as a negative control, RT(-). 