Where the mutation is identified after submission by an expert laboratory, this is noted under remarks which also provide the method of analysis. Additional information for other chromosomes in these hybrids may have been obtained incidentally as a consequence of the way blots were constructed for the analyses. In 1994, the Repository began using PCR analysis with locus-specific primers in lieu of Southern blot hybridization analysis for characterizations. The number of primer pairs used has increased significantly since the offering of regional mapping panels in 1994. Negative controls are also included.
Chromosomal analysis supports the molecular quality control of DNA preparations.
Cytogenetic analysis assures that the human chromosome that is critical to the use of the hybrid as a mapping reagent is intact and is present in a high percentage of cells. These cells are sampled from the inoculum of the last passage prior to harvest and a second sample is obtained at the time of harvest. Twenty-five cells are analyzed for each sample. In cases where G-band ascertainment of the critical chromosome is difficult, FISH analysis using whole chromosome paints, centromere probes, or probes to specific loci are included to resolve any ambiguities. Feedback from DNA recipients including utilization surveys and publications citing the use of Repository DNA samples are also reviewed for consistency with the description.