DPB1 typing with Null allele should be treated as homozygous during TCE group scoring

[zabeen]

Describe the bug Patient typing at DPB1 had a null allele (DPB1 *02:01, *64:01N) and the donors in their search results were not scored for DPB1 match grade, instead they all had the assignment of U.

To Reproduce Steps to reproduce the behavior:

1. Run a search request with DPB1 scoring enabled, with DPB1 excluded from aggregate scoring. DPB1 typing should contain one null-expressing allele (e.g., DPB1 *02:01, *64:01N) - the exact patient search HLA that triggered this ticket is available on request.
2. On completion of search, download the results file from blob storage.
3. Scroll down to a scoring result for a donor typed with DPB1, and you will see following:

   "Dpb1": {
                       "IsLocusMatchCountIncludedInTotal": false,
                       "MatchCategory": "Unknown",
                       "MatchCount": 0,
                       "IsLocusTyped": true,
                       "MismatchDirection": "NotApplicable"
                   }

4. AI Logs for search will also show the following message for each donor that had DPB1 typing: "Could not find patient TCE group pair: (3, ) in hardcoded DPB1 TCE group matching behaviour. Something has likely gone wrong, and the Unknown grade will be used until this is fixed."

Expected behaviour Expect for null-containing DPB1 typings to be treated as if the patient (or donor, where applicable) is homozygous for the expressing allele, and the TCE groups to be calculated accordingly.

Inputs/Outputs Patient HLA and original search results available on request.

Atlas Build & Runtime Info (please complete the following information):

• Runtime Environment - Anthony Nolan LIVE-ATLAS
• Atlas Version - 1.4.2
• GitHub commit ID of Atlas build - stable/1.4.2 tag

Additional context Link to DPB1 TCE group calculator that needs to be extended with null-handling logic

[zabeen]

Testing Notes

• Detailed testing of this fix can only really be done by a user experienced with DPB1 scoring, so that will have to wait until the fix has been released to AN UAT.
• However, @DmitriyShcherbina can do a simple test which is to re-run the same patient in AN dev (DPB1 scoring should be enabled, no need for match prediction) and just check that Dpb1.MatchCategory for matching donors typed with DPB1 do not say "Unknown". I will send the patient HLA via DM.

[DmitriyShcherbina]

@zabeen dev testing status: ok In my test result Dpb1.MatchCategoty has Mismatch value

[zabeen]

@DmitriyShcherbina fantastic, LGTM!