I am designing primers for ChIP qPCR. One of the genomic region has high AT content. I am not getting any primers for amplicon length of 75-160bp. I even tried getting primers with low Tm. How do I go about it?
Did you try adding some GC bases (3-4) to 5' end of the primer just before your sequence of interest? This could be useful to obtain a lower Tm without affecting specificity to recognize the sequence.