PCR-based human leukocyte antigen (HLA) DQ alpha typing of blood stained light and dark blue denim fabric.

Obtaining typable PCR products from DNA purified from blood stained blue denim has been difficult since inhibitors of PCR in blue denim apparently co-purify with the DNA. Organic and chelex extraction methods were tested for their ability to purify typable DNA from either light or dark blue denim fabric both stained with blood. DNA purified from the light blue denim using either method was successfully used in obtaining correct HLA-DQ alpha typing results. The chelex, but not the organic, procedure was able to yield typable DNA when the dark blue denim was the substrate. Therefore, the chelex method may be more effective than the organic method in preventing compounds that inhibit PCR from co-purifying with the DNA.