aDNA and Primer Contamination

The largest issue in ancient DNA analysis is the contamination of the sample by exogenous DNA. This article describes many of the common sources of DNA contamination as well as the methods commonly used now to avoid it -- from contaminants during sample excavation to contaminants during DNA analysis in the lab. Researchers conduct a study in which highly identified remains are excavated by a small team of known researchers, employing all known methods for reducing contamination during sample extraction. They conclude that if proper extraction protocols are followed, sample contamination before arrival at a lab can be almost completely eliminated. However, they also discover that samples can become contaminated with exogenous human DNA in dedicated aDNA lab setting by primers -- a previously unexplored source of contamination. Primers, though synthesized in a lab, are handled by humans. This article identifies a specific primer manufacturer but also concludes that primer contamination is common.

See the original article here.