A method for the purification and recovery of genomic DNA from an HLA DQA1 amplification product and its subsequent amplification and typing with the AmpliType PM PCR Amplification and Typing Kit.

DNA from plucked single hairs from ten individuals was extracted by two different methods and subsequently amplified and typed using the AmpliType HLA DQ alpha Forensic DNA Amplification and Typing Kit. The remaining untyped portions of the DQA1 amplification products were stored refrigerated or frozen for two weeks and subsequently purified using Centricon 100 microconcentrators. Genomic DNA was recovered from the DQA1 amplification PCR and used again as a template for a subsequent multiplex PCR. Twenty microL of each retentate were amplified and typed with the AmpliType PM PCR Amplification and Typing Kit. All typing results were consistent with DQA1 and PM results of control hairs and reference blood samples from the donors and all results were consistent with those obtained when the samples were typed solely for PM. The DQA1-Centricon 100-PM approach is useful when the genomic DNA from an evidentiary sample has been used completely for HLA-DQA1 typing, so that only the amplified product is remaining. The typing of five more genetic markers can be achieved from a HLA-DQA1 sample, so additional information for identification purposes could be provided. However, genomic DNA as well as the DQA1 product are recovered and the latter will also serve as a template in the subsequent PM amplifications. Therefore there will be more DQA1 product after the PM amplification than would be expected when only genomic DNA was used as a template. Thus certain practices should be considered when reading the types from PM probe strips if this DQA1-Centricon 100-PM approach is used.