Most DKMS donors are typed in HLA-A, -B, -C, -DRB1- DQB1 in high resolution, allowing easy identification of 10/10 matches. In case donors do not fulfill these requirements or if additional information is needed before confirmatory typing to identify the best matching donor, extended typing can be requested.
The range of results being requested varies between the whole set of HLA genes (HLA-A, -B, -C, -E, -DRB1, -DRB3/4/5, -DQA1, -DQB1, -DPA1, -DPB1), as well as KIR, CCR5 and MICA/B. It is also possible to request only single genes, e.g. in search of a permissive/non-permissive mismatch of HLA-DPB1, a request only for HLA-DPB1 is possible.
Included in a typing tequest is:
In case of a pre-selection of multiple potentially matching donors, it might be helpful to know the infectious disease markers or the CMV status to determine the best matching donor(s). IDM requests can be filed in parallel to a typing request, but can also be requested separately. Besides our standard set of IDMs, it is also possible to request individual markers separately.
Included in an IDM request is:
As most DKMS donors are typed at high resolution for HLA-A, -B, -C, -DRB1, -DQB1, and -DPB1 by NGS, the error rate is very low (see Baier, D.M., Hofmann, J.A., Fischer, H. et al. Very low error rates of NGS-based HLA typing at stem cell donor recruitment question the need for a standard confirmatory typing step before donor workup. Bone Marrow Transplant 54, 928–930 (2019)). Therefore, identification of a fully matched donor is often possible at the start of a search. Further, some of our donors already have confirmed typing results from previous requests. However, the availability of the donor and medical information might not be up-to-date. DKMS offers transplant centers the possibility to request a HAC instead of CT, in order to speed up donor screening and proceed faster to workup as HLA verification typing is only performed on the donor selected for workup. The typing will then be performed during workup from blood collected with the pre-collection samples, taken from the donor on the day of physical examination. The HLA verification typing results must be provided before the donor’s clearance and thus before the donor starts with G-CSF application or before patient conditioning is initiated.
The following criteria need to be fulfilled to request a HAC:
Included in a HAC request is:
Important note: A HAC can be performed instead of, but not in advance of, a CT request. It is not allowed that the transplant center request a CT shortly after a completed HAC. The information session and Health History Questionnaire included in a HAC are the same as performed during a CT request. If the transplant center requires the donor's IDM testing results for donor selection, a CT must be requested directly as the initial request.
HLA verification typing of donor and recipient is always required before a recipient can receive a stem cell product from an unrelated DKMS donor and must be performed either before or during workup. HLA verification typing must be performed from a fresh sample of the potential donor.
When Confirmatory Typing is requested and processed before workup, it includes the following elements:
The maximum amount of blood to be drawn at CT must not exceed 50 ml.
Research studies to support donor selection may be important for the transplant outcome of the patient. DKMS generally supports studies if they can result in a benefit for patient care or increase safety of donors and the additional burden on the donor is acceptable.
About 1% of the Northern European population carries the 32 mutation of the CCR5 gene homozygously. Homozygous carriers of this mutation are resistant to M-tropic strains of HIV-1. Therefore, CCR5 testing can be performed for patients with a hematological disease who are also HIV-1 positive. DKMS has performed CCR5 tests for all donors at donor recruitment since 2014.