Mitochondrial DNA testing should only be performed by laboratories with considerable experience in handling the unusually difficult samples that require this form of testing. The primary reason for this is that experienced labs can extract minimal amounts of mtDNA from difficult samples. In the event of a sample failure, an inexperienced lab would never know whether their extractions and PCRs were simply not sensitive enough, or whether the sample lacked non-degraded DNA altogether. In addition, contamination controls are heightened in a mitochondrial DNA laboratory, where working at the limits of sensitivity is standard operating procedure.