I have a splicing mutation in my candidate gene XX. To find out what is the alternative splicing caused by this mutation, I designed two forward primers (F1 and F2) and one reverse primer (R1) flanking the splicing mutation. F1R1 product is expected 450 bp, and F2R1 product is supposed to be 340 bp. I used F1R1 to check the cDNA of the two parents but both got products around 350 bp, which made me suspect that the F1 primer was actually F2 primer. I sent the PCR product for sequencing and the result confirmed my doubt. It turned out that my helper made a mistake when making the working solution. To avoid this kind of mistakes again, I asked her to number all the primer stock solutions and write the number on each tube of the working solution. Using numbers is much clearer than using primer real names when there are multiple primers with similar names.