QuantiBlot Test

The QuantiBlot test is used to determine how much primate DNA is in a sample. It looks for a specific sequence that is repeated over and over again in the centromeres of primate DNA. The point of the QuantiBlot is that it’s a quantitative test, which should give a mass, in nanograms, for how much primate DNA is in the sample. The test is usually done to determine whether there is enough DNA for an RFLP test, or if a PCR test is more suitable. It is designed to be run with controls of known concentrations of human DNA, usually 0.15ng, 0.3ng, 0.6ng, 1.2ng, 2.5ng and 5ng. The test results are then compared to each of these bands so you can tell what range they fall into. However, the report does not give any numbers and says only that a “very low concentration” was obtained. This likely means that it was fainter than the 0.15ng control band. This is further supported by the fact that 0.1ng-0.2ng is about the limit where PCR STR analysis becomes unreliable, and the report states that the quantity detected was “insufficient” for this test.

Quantiblot results for single plucked human hairs range from 0.28ng to 1.64ng. So we are talking about a very small quantity of DNA, even less than would be found in the root of a single human hair. This is almost certainly the result of contamination. There a variety of possible sources of contamination in the story of this sample, including:

• Skin cells from the priest handling the wafer before blessing it.
• Cells from the individual who received the wafer (hand or tongue?)
• Human skin cells in the dust in the candlestick.
• Cells from the communion assistant handling the wafer to put it in the bowl.
• Cells from any of the various people staring into the bowl, photographing the sample, transferring the contents into the test tube, or taking the sample for the lab.

If anyone doubts that contamination by a single hair would be possible, all you have to do is look closely at the pictures.

If all of that red tissue was human, or if the numerous cell nuclei observed on the microscope slides were human, this test would have yielded a much higher concentration of human DNA.

There is nothing about this result that is surprising for an ordinary wafer that has been handled by multiple human individuals.