Help reading chromatogram A genetic variation is found in this chromatogram: ![]( It says that the "reference sequence" is the top line and that I can use the general genetic code to find the reading frame. I can see that there are two N's instead of a G and a C. However I don't know what this means. I'm also not sure how I'd find the reading frame? I suppose I could look for a start and stop codon but I could read them both ways? Last question: Is this change likely pathogenic? I'm not sure how to classify a variation as pathogenic or not.

So the two Ns that you see are not necessarily variants, but rather likely just poor quality reads. Essentially when you sequence DNA and the sequencer can't make a call as to what the base is, it will just designate it N meaning that the base could be any of the four DNA bases.

As for finding the reading from, if you know this sequence contains a stop codon, that helps, and just look for any of the stop sequences. If not, look for bases that match codon sequences and if you get a full strand of sequence that codes for amino acids you will likely be correct.

For reference here is a link to a codon chart that will help you decipher the reading frame.

Does that help?