INTERLABORATORY COMPARISON OF AUTORADIOGRAPHIC DNA PROFILING MEASUREMENTS - PRECISION AND CONCORDANCE

Knowledge of the expected uncertainty in restriction fragment length p olymorphism (RFLP) measurements is required for confident exchange of such data among different laboratories. The total measurement uncertai nty among all Technical Working Group for DNA Analysis Methods laborat ories has previously been characterized and found to be acceptably sma ll. Casework cell line control measurements provided by six Royal Cana dian Mounted Police (RCMP) and 30 U.S. commercial, local, state, and F ederal forensic laboratories enable quantitative determination of the within-laboratory precision and among-laboratory concordance component s of measurement uncertainty typical of both sets of laboratories. Mea surement precision is the same in the two countries for DNA fragments of size 1000 base pairs (bp) to 10,000 bp. However, the measurement co ncordance among the RCMP laboratories is clearly superior to that with in the U.S. forensic community. This result is attributable to the use of a single analytical protocol in all RCMP laboratories. Concordance among U.S. laboratories cannot be improved through simple mathematica l adjustments. Community-wide efforts focused on improved concordance may be the most efficient mechanism for further reduction of among-lab oratory RFLP measurement uncertainty, should the resources required to fully evaluate potential cross-jurisdictional matches become burdenso me as the number of RFLP profiles on record increases.