3 and 4 mismatch searches have now been implemented for Cord searches. Here are some things you need to know: 


Future improvements

As mentioned above, since 3 and 4 mismatch CBU search results do not have any match probabilities calculated, the results are currently sorted within their match class (e.g. 5/8, 4/8) only by TNC or CD34. The Hap-E algorithm in the new Search & Match service returns more potential CBUs than the legacy system. Many of these “extra” CBUs tend to be low probability CBUs that have low resolution or missing typing. This is not actually “wrong” because they are a potential match, but many of these tend to not be good candidate CBUs. 

This means that a poorly matched CBUs with high cell dose are at the top of the list and potentially better CBUs with a high enough cell dose are lower. This has always been the case in legacy Search & Match as well, but because of the increased number of valid potential matches, it is a bit harder to find suitable CBUs than the legacy Search & Match. 

In an effort to improve the search coordinator's experience when performing 3 and 4 mismatch searches we are currently developing several features that should improve the efficiency of finding suitable CBUs. These are:

Score based sorting of 3 & 4 mismatch search results

In general it is true that the more highly typed a CBU/ donor on a match list is, the higher the probability of a match. As we are currently not able to provide match probabilities and it will take a few months to fully develop, we will use a score based approach. This works in the following way

Match probabilities