What does it mean when a sample fails QC?
The DNA, cDNA of every diagnostic sample is run with a standard housekeeping gene to ensure successful nucleic acid extraction. If the housekeeping gene is negative, or very weak (Cycle Threshold value greater than 30), we re-extract the nucleic acids from the back up sample, and run it through PCR a second time. If the housekeeping gene for the backup sample is also negative or weak, we consider the sample to “fail quality control”; that is, there are not enough cells in the sample to accurately test for the presence of a pathogen. You have the option of submitting another sample if the package is shipped correctly. Recently, our facility has introduced a new methodology to reduce these instances (see question 3 below).
