I have design a pair of primers for ACTN1 that amplify a fragment of 188bp. During a year, in all the PCR I have performed I obtained a 188bp fragment but the last time I use them the fragment was about 150bp. Thinking about a problem with the primers I prepare new aliquots but I still obtain a band of 150bp. Any idea about what can happen? I thought about different transcripts but in primer Blast I only found amplification for 188bp.
Thanks you very much for your help in advance.