Next step - genotyping!
We’ve run our second round of extractions on our current batch of samples to increase the chances of success for our customers. In one case, we firstly tested an envelope flap from 1941, and found minute amounts of DNA, insufficient for further progression. We then tested the stamp and found a workable amount of DNA to enable us to prepare this sample for genotyping.
Our preference is to test the flap of an envelope before a stamp, unless there is a problem with the flap, or the customer requests otherwise. This is based on the likelihood of a letter writer being the person who sealed their item, whereas a stamp may or may not have been fixed by the writer. Of course, any variation is possible. The writer may have sealed both, or neither. This is a risk we highlight to our customers prior to them using our service. In the case of the 1941 sample above, we let our customer know that we had a poor result when testing the flap, and that the stamp is our best option.
Our final results then for this 25-sample batch is that no useable DNA was found in five samples. In five further samples, we found borderline-acceptable amounts of DNA but will attempt to progress these to enable genotyping. That leaves us with 15 samples that meet the recommended DNA quantity for progression.
That means we have 20% of samples that we cannot progress further, or 80% that we can. We will publish the results of our genotyping over the next few weeks.
Our view is that every individual case for which we get a positive result is a fantastic outcome for our customers.
We know we will never be able to have a 100% success rate - that is simply not possible - but we are thrilled with the results we are achieving and are working to improve our outcomes at every step!