One potential source of inaccurate genomic data is sample contamination. We define contamination as the accidental mixture of DNA or RNA from two or more individuals from the same species. Contamination between different species is also possible. Anytime samples are pipetted (e.g. during collection, storage, or extraction) there is an opportunity for contamination. Improper shipment of samples in well plates from a repository to a processing center may also result in contamination.
Those sequence contaminations are a serious concern to the quality of the data used for downstream analysis, causing misassembly of sequence contigs and erroneous conclusions. Therefore, the detection and removal of sequence contaminants is a necessary and required step for all sequencing projects.