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Questions are divided into the following subjects:


 I forgot my username/ password. What should I do now?
Your username will be your registered email address, however, if you have forgotten it please contact the WMDA office by email  If you have forgotten your password, click on the 'Forgot Your Password' link, enter your email address and click on 'Send Password Reset Link'.  You will then receive an email with a link to follow - click on the link and reset your password. Please notice you must use the link within 30 mins, otherwise, you will trigger an error page "Sorry, an error has occurred".
 How can I get access to the WMDA Search & Match Service?

Requesting authorization:

The donor/CBU search service is only available for registry staff members and staff members of organisations assisting in searches for unrelated transplants. Find below the procedure to get access for the different types of users. You can register on the WMDA website

 What are the different services WMDA provides as part of its support services?

WMDA provides search advise for difficult cases. You can request a search advise at the bottom of the Update patient screen and the HLA experts will then help you to determine the best search strategy for your patient.

 What to do when I see the page "Sorry, an error has occurred"

If you see this error, there can be several reasons that cause this error:
1. Your browser cache for search results may cause the issue. Please clear your browser cache and try again.
2. Can you open the login page ( If you can, and after you fill in your credential you see this error, then that is because you provided a wrong email address or password. Please double check your credentials.
3. If you cannot remember your credentials and try to reset the password, but click the password reset link more than 30 minutes after it was generated, you can see this error page. Please use the password reset link in 30 mins.


 How can I quickly access the details of a patient within WMDA?

Patient information can be accessed from the 'Patient List' by selecting the "Patient ID'. The patient information can also be accessed from the Patient's Match Result List by opening the 'Patient Details' box and selecting the 'Edit Patient' button.

 Why can I not find a particular patient?

If you cannot find your patient within the default Active list remember to search the Inactive list as well. 

Users will have access to patients registered by other users at their organisation as well, which is also split into 'Active Patients' and 'Inactive patients' 

 I have a large list of patients. How can I easily find my patient?

There are different tools in the patient list to search or sort your list which will make it easier to find your patient:

  • Use the Search by patient ID box when you know the patient ID or part of it.
  • You can sort the list on every column (except from the results column), so you can for example sort on birth date and then find your patient.
  • When you are looking for a patient not entered by yourself, you can sort on username at the view with all patients from your organisation.
 Does De-activating a patient record delete it from the system?

No. De-activating a patient will just remove it from the OptiMatch server and the 'Active patients' list and place it in the 'Inactive patients' list.

 Can I Re-activate a patient record?

If you need to re-activate a patient, from the Patient List section open the 'Inactive patients' list, search for the relevant patient and open the patient record.  At the bottom of the page select or de-select the appropriate search type you wish to run and click on the red 'Reactivate patient' button. This will automatically trigger a re-run of the searches that were performed before and move the patient to the active list.

 I cannot change any details from my inactive patient before reactivation. Is this correct?

When you open a patient record from your inactive patients, the details cannot be edited. If you need to change details like weight, you first have to reactivate the patient. When the record is placed in the Active patient list again, you can update the details of your patient.

 How is the patient list sorted by default?

The patients in the patient list are default sorted on the date of last viewed. The records that have not been viewed at all are placed at the top, followed by the most recently viewed record.

 When I switch between views (just my patient vs all patients from my organisation) at the Inactive patient list, I am referred back to the Active patient list. How can I switch between views in the Inactive patient list?

The easiest way is to change the view first in your Active patient list and then go to the Inactive patient list.

 Does the system auto correct HLA?

No, the system does not auto correct HLA information, but may give you error warnings as applicable.

 What is the difference between urgent and non urgent patients?

Urgent and Non-Urgent indicators on patients are a tool for you to use to prioritise your patient searches. At this time, the Search and Match Service does not use this information and will not affect the speed of your match run.


 What is asynchronous matching?

Asynchronous matching is a process of running searches in parallel. It allows you to enter a patient and start the search run, and proceed with other activities within the application like entering another patient or reviewing another match list while the search runs in the background. The user does not have to wait for the current search to finish before proceeding with other activities.

 Why do some search requests take long to retrieve?

Many factors can impact how long it takes to retrieve search results. The most likely reasons that your search is taking some time is that it is a difficult search or the HLA of your patient is very common and will retrieve many records. We initially only run a 10/10, 8/8 or 6/6 search to make sure we retrieve you results as quickly as possible. Mismatch searches can take longer since there are many more options to assess before providing the results.

 Can I cancel a search if it’s taking too long?
 It is not necessary to cancel a search. We recommend logging out of the application and returning at a later time to review your results.
 Which match types are used for the initial donor/cord match run?

The system by default runs for donors a 10/10 match run using the haplotype frequency algorithm if all 5 loci (A,B,C,DRB1,DQB1) are available for the patient. If only 3 or 4 loci are available, the system will scale down to respectively a 6/6 or 8/8 match run. 10/10, 8/8 and 6/6 are all considered as zero mismatch runs and will not include mismatch donors in the results.

The system by default runs for cords a ≥8/10 match run at allele level using the haplotype frequency algorithm.

 What does Run Mismatch search mean?

By default, the Search & Match Service only provides 10/10, 8/8 or 6/6 matches initially. Selecting the 'Run Mismatch' search button allows you to request a mismatch search to review e.g. 9/10 or 7/8 match results. Once those results return, you will be able to review them by specific loci mismatches or any loci.

 Is it possible to run a mismatch run at the first initial match run?

No, at this moment you can only run a zero mismatch donor and/or ≥8/10 cords run as a first match run. You have to requested the mismatch donor run after you retrieved the zero mismatch run results.

 What is the difference between Allele and Haplotype frequencies?

Allele frequencies give the proportions of individual alleles. Haplotype frequencies give the proportions of specific haplotypes i.e. several alleles in phase and therefore preserve linkage information.

 What Haplotype Frequencies will be used for the probability matching?
The Search & Match Service uses a Global Frequency set determined from the comprehensive donor file. Read more on the following page.
 Can I switch off the Predictive Search and run it just like the old system?
 You can switch to use allele frequencies instead of haplotype frequencies, which is the matching approach/method that the old system used. However, all matching algorithms vary slightly so the new search powered by OptiMatch may not match results from the old system, even with allele frequencies in use.
 How can I request a Search Advise for a Patient?

If you are experiencing difficulties in your selection of a donor/cord for your patient, you can request a search advice from the WMDA HLA experts. To request an advise, go to your patient list, click on the patient ID and at the bottom of the Update patient form you will find a button with 'Request Search Advisory'. An email message will then open with the patient information and some additional fields with requirements. Please fill out as much as possible and send the email. You will receive the advice also by email.

 What is the difference between setting filters and heading/on-screen filters within the search results report?

Setting the filters in the 'Search Settings' on the Search results page prompts a new search request with those parameters. These filters will also not influence the number of results you will retrieve and will be saved in your search results.

The heading/ on-screen filters on the match results table will filter and reduce the results list that is already available. Donors and cords will retain their row number from the original list without any on-screen filters applied. The on-screen filters will not be saved to your search results and when you leave the search results page the on-screen filters will no longer be there when you come back.

 Are changes to the search report settings reset by the system?

Only changes applied from the search setting box will be saved to your search results. Any other on-screen filters or flags won't be saved and are reset by the system when you leave the search results page.

 It seems like the search results are automatically ordered on age for adults and TNC for cords. Is that correct?

The default sorting criteria from OptiMatch for donors are: 

1. HLA

2. probability in 10% intervals

3. donor age in 5 year intervals for adults

The default sorting criteria from OptiMatch for cords are: 

1. HLA (6/6, 5/6, 4/6 categories)

2. Number of total nucleated cells (TNC) for cords within HLA match category

 What are the DBP1 TC3 evaluvation conditions

DPB1 TCE3 evaluation is performed only for A-B-DR(B1) typed donors under the following conditions: 

  • Patient DPB1 values must be present. Typing ambiguities in the form of multiple alleles codes, G-codes, etc. are allowed.
  • Donor DPB1 values must be present. Typing ambiguities in the form of multiple alleles codes, G-codes, etc. are allowed.
  • The donor must be in the group of potential "9/10" and "10/10" identical donors. Therefore, it is implicitly assumed that a 5-locus search report is retrieved and can be accessed. In case of a 4- or 3-locus search reports or deactivation of the grouping by allele differences, there will be no TCE3 grading.

As part of the DPB1 TC3 grading filter, you can filter the results by the following options: Permissive, Non-permissive in HvG direction, Non-permissive in GvH direction, Ambiguous, Unknown.

Although the DPB1 TC3 filter is available for cords, the results haven't been validated so it shouldn't be used.

 What sequence do donors appear in on the reports? Are any types of donors given precedence?

The default sorting criteria from OptiMatch are:

1. HLA

2. probability in 10% intervals

3. donor age in 5 year intervals

 The cords results in the former BMDW were displayed according 6/6, 5/6, 4/6 or less. Is that also in this system?

Yes, all cords are sorted based on out of 6 HLA matching and TNC. So on top of your results you will find potential 6/6 matched cords with the largest unit (based on TNC) one on top of the page, followed by the 5/6 cords and 4/6 cords (depending on the match type you selected).

 I would like to sort a haplotype frequency-based search report according to HLA-C. Is that possible?

 It is not possible to sort the search results in the match results table. You do have the ability to use many filters and to use different match types.

 Why are there sometimes probabilities missing?

These donors don't have haplotype probabilities. This is usually the case when the phenotype could not be explained with the haplotypes given in the frequency set (inexplicable donor). Without haplotypical context, the programme gives only allele frequencies for the tested loci.

 Why is, for example, a donor with B*15:BPXE not shown as a potential match for a patient with B*15:03? And why was such a donor shown in the “old BMDW”?

Part 1: Since B*15:BPXE = B*15:03/61/74/103 a donor with this codes is a potential allele match for the patient. According to the official WMDA serology/DNA correspondence table, B*15:61 and B*15:74 have a serology of B15/B70 while B*15:03 is B72 and B*15:103 is B70. As a consequence a serology of B15 rules out B*15:03 and this donor is no longer potentially identical (on the allele level). Another explanation could be the limited length of donor lists.

Part 2: In the old BMDW serology was ignored when DNA typing was available so B*15:03 was not excluded. The new system does not modify or ignore donor data and respects and relies on the responsibility of the providing registry for its data.

Background: Unfortunately, for many donors serology was derived from DNA (by using the first field for the serological assignment) and vice versa (by appending “:XX” to the serological assignment) and often eventually both values are reported. In the case discussed, B*15:BPXE probably was translated back into B15 which is most likely wrong. This is a typical and (with certain registries) frequent case but there are many more unexpected DNA-serology correspondences that can give rise to exactly the same situation.

 Why is a male donor listed after a female donor of the same age and HLA? Why is a donor with an identical CMV status listed after one with a missing or different CMV status?

OptiMatch does not consider binary attributes like gender or CMV for  sorting at all. If you see a rich donor list and prefer, for example,  male donors you should use the filtering capability of OptiMatch.

Rationale: There is no agreed concept for weighing secondary match  criteria like age, gender or CMV against each other. The approach to sort by probability in blocks and then by age plus ad hoc filtering gives the user maximum control of the appearance of the list.

 Why is a matching donor who is typed at higher resolution listed after donors typed at lower resolution?

This can happen only if the difference in resolution is not  considered sufficiently relevant in the given context by OptiMatch. Below are some possible (not mutually exclusive) reasons:

  1. The allele designations encode for the identical ARD (antigen  recognition domain) and OptiMatch only matches for the ARD part of the HLA protein complex. For example B*07:ANVB stands for B*07:02/07:61 which both encode for the same ARD (here: exon 2 and 3). Hence OptiMatch is regarding the codes B*07:02, B*07:61 and B*07:ANVB all as allele matches for each other but might give different matching probabilities for phenotypes containing each of those three codes since haplotypes  involving B*07:02 and B*07:61 are having individual frequencies.
  2. The resolution only looks higher but, in fact, is lower (e.g.  B*15:12 currently is only a single allele while B*15:12:01G covers three), identical (e.g. A*80:01, A*80:01:01 and A*80:01:01G cover exactly the same alleles) or not directly comparable since each code is containing some alleles not covered by the other (e.g. comparing  B*07:TDVB and B*07:02:01G the former also covers a lot more variants of  B*07:02 like  B*07:02:02 to B*07:02:05 while it is excluding other alleles like B*07:44 and B*07:49N).
  3. The broader code only contains additional alleles which have never  been observed in the population whose haplotype frequencies are used - at least not in a relevant haplotypical context. Their frequency could  also be so low that it is disregarded due to rounding or the 10%  probability grouping explained elsewhere. This applies, in particular,  to all null variants of expressed alleles with identical first two field  designations.
 Why do I see two alleles in bold on a locus in the one mismatch(9/10) category?

In rare cases the match program cannot decide which of two B locus results are a mismatch, in those cases both  are given in bold. For example, the patient is B*27:05, 44:03; the donor is B*44:ABYM, 44*AFFK. In this case both multiple allele codes include 44:03 therefore the match program cannot choose between them. See example image below where donor 12 on the search report is being marked as having two HLA-B mismatches, when actually it is only a single mismatch.


 Why, despite complete patient HLA, can only a 6/6 but not a 10/10 search report based on haplotype frequency be generated?

The patient's 5 locus phenotype (10/10) cannot be explained by the haplotypes used for probability matching. The algorithm tries to fall back to 4 locus phenotypes (8/8) and 3 locus phenotypes (6/6).

 By default the system should run a 10/10 matched donor run. Why do I get only 8/8 or 6/6 results?
  • The patient's 5 locus phenotype (10/10) cannot be explained by the haplotypes used for probability matching. The algorithm tries to fall back to 4 locus phenotypes (8/8) and 3 locus phenotypes (6/6).
  • If the HLA of the patient does not contain information for all 5 loci, the system will automatically scale the match run down to 8/8 or 6/6 depending on the available HLA information of the patient.
 Why is no probability stated for a highly suitable donor in the haplotype frequency-based search report?

Most likely, the donor's phenotype cannot be explained by the haplotypes used for probabilistic matching.

 Why does a DQ mismatch donor not show for my patient under the 8/8 donor list?

Currently, 10/10, 8/8 and 6/6 lists are reserved for donors that have no known mismatches. Donors that have known mismatches for your patients will only be returned when you select "Run a Mismatch Search" and then select to view a 9/10 or 7/8 match type results list.

 How does WMDA handle A*02:01 vs *02:03. Antigen =\ or allele =\. Another example is B* 15:01 vs 15:03.

A*02:01 (2) vs. 02:03 (203) is an allele mismatch because A203 is an associated antigen to A2.

B*15:01 (62) vs. B15:03 (72) is an antigen mismatch.

 I performed a cords match run with match type ≥4/6 with class I at antigen level and class II at allele level. Are the probabilities then also determined on this particular match type?

The probabilities shown in your match results table are based on allele level matching and do not correspond with this particular match type.

 If I have a patient with a certain heterozygous locus, how can I ensure that HvG-identical homozygous donors are listed as high up the donor list as possible?

Currently this feature is not implemented. However, this could be a feature for upcoming versions of the matching program.

Educational newsletters

No 1: The Sorting order within a donor search report

No 2: Printing of search reports

No 3: New feature added: DPB1 TCE3 model

No 3b: DPB1 TCE3 model update and revised information

No 4: New features added

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