Genotyping in Sickle Cell Disease Patients: The French Strategy

Background: The provision of compatible blood products to patients is the most essential task of transfusion medicine. Besides ABO and Rh, a number of additional blood group antigens often have to be considered for the blood supply of immunized or chronically transfused patients. It also applies for platelet antigens (HPA) and neutrophil antigens (HNA) for patients receiving platelet or granulocyte concentrates. Here, we describe the molecular screening for a number of blood group, HPA, and HNA alleles. Based on the screening results we are building up a regional blood donor registry to provide extended matched blood products on demand. Methods: We developed and validated TaqMan™ PCR and PCR-SSP methods for genetic markers defining 37 clinically relevant blood group antigens (beyond ABO and Rh), 10 HPA, and 11 HNA. Furthermore, we describe a feasible method for fast molecular screening of the HNA-2^null phenotype. All data were statistically evaluated regarding genotype distribution. Allele frequencies were compared to ExAC data from non-Finnish Europeans. Results: Up to now more than 2,000 non-selected regular blood donors in south-west Germany have been screened for blood group, HPA, and HNA alleles. The screening results were confirmed by serology and PCR-SSP methods for selected numbers of samples. The allele frequencies were similar to non-finnish Europeans in the ExAC database except for the alleles encoding the S, HPA-3b and HNA-4b antigens, with significantly lower prevalence in our cohort, as well as the LU14 and the HNA-3b antigens, with a higher frequency compared to the ExAC data. We identified 71 donors with rare blood groups such as Lu(a+b-), Kp(a+b-), Fy(a-b-) and Vel-, and 169 donors with less prevalent HPA or HNA types. Conclusion: Molecular screening for blood group alleles by using TaqMan™ PCR is an effective and reliable high-throughput method for establishing a rare donor registry.

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“…Similar concepts for the extended matched blood supply are established in different countries worldwide [34,35,36,37]. …”

Section: Discussionmentioning

confidence: 99%

Towards a Regional Registry of Extended Typed Blood Donors: Molecular Typing for Blood Group, Platelet and Granulocyte Antigens

Portegys

Rink

Bloos

et al. 2018

Transfus Med Hemother

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“…No anti-D have ever been reported in carriers of RHD*DAU13 or RHD*DUC3, and the parallel c.48C>G substitution present in many African RHCE alleles is considered by some authors to be benign. 70,90 On the contrary, for the controversial RHD* weak partial D 4.0, 2, 43-45 many interactions differ from wild-type RhD (14 different interactions involving four residues and two protein domains), which would predict the risk of anti-D production. Compared to its high prevalence in individuals of North African descent, very few cases of anti-D production have been described for this variant, mostly not consistent with alloanti-D, 27,43,45 and autoadsorption studies are lacking.…”

Section: Discussionmentioning

confidence: 99%

“…The association of c.48G>C and c.1136C>T (p.W16C and p.T379M) found in the RHD*DAU13 allele is probably not associated with the risk of anti‐D production either and does not warrant transfusion with D– RBC units. No anti‐D have ever been reported in carriers of RHD*DAU13 or RHD*DUC3 , and the parallel c.48C>G substitution present in many African RHCE alleles is considered by some authors to be benign 70, 90 …”

Section: Discussionmentioning

confidence: 99%

Insights intoanti‐Dformation in carriers ofRhDvariants through studies of3Dintraprotein interactions

et al. 2021

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Background Many RhD variants associated with anti‐D formation (partial D) in carriers exposed to the conventional D antigen carry mutations affecting extracellular loop residues. Surprisingly, some carry mutations affecting transmembrane or intracellular domains, positions not thought likely to have a major impact on D epitopes. Study Design and Methods A wild‐type Rh trimer (RhD1RhAG2) was modeled by comparative modeling with the human RhCG structure. Taking trimer conformation, residue accessibility, and position relative to the lipid bilayer into account, we redefine the domains of the RhD protein. We generated models for RhD variants carrying one or two amino acid substitutions associated with anti‐D formation in published articles (25 variants) or abstracts (12 variants) and for RHD*weak D type 38. We determined the extracellular substitutions and compared the interactions of the variants with those of the standard RhD. Results The findings of the three‐dimensional (3D) analysis were correlated with anti‐D formation for 76% of RhD variants: 15 substitutions associated with anti‐D formation concerned extracellular residues, and structural differences in intraprotein interactions relative to standard RhD were observed in the others. We discuss the mechanisms by which D epitopes may be modified in variants in which the extracellular residues are identical to those of standard RhD and provide arguments for the benignity of p.T379M (RHD*DAU0) and p.G278D (RHD*weak D type 38) in transfusion medicine. Conclusion The study of RhD intraprotein interactions and the precise redefinition of residue accessibility provide insight into the mechanisms through which RhD point mutations may lead to anti‐D formation in carriers.

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“…We have observed that when the molecular report does not provide an interpretation and recommendation, clinical practictioners not experienced in blood group genetics hesitate to interpret RHD genotyping results as D+ or D−. For the purposes of RhIG adminstration and transfusion, interpretation of an RHD genotype requires not only pertinent experience but also knowledge of the history 2,5 as well as the current evolving data [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] and literature reports 15,16,[23][24][25][26] of the risks for alloimmunization associated with specific RHD genotypes. 27 Hospital computer systems may require updating to accomodate new requirements, such as the ability to change a prior serologic D typing result, when it is overridden by a different D type based on RHD genotyping results.…”

mentioning

confidence: 99%

It's time to phase out “serologic weak D phenotype” and resolve D types with RHD genotyping including weak D type 4

et al. 2020

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Genotyping in Sickle Cell Disease Patients: The French Strategy

Cited by 19 publications

References 45 publications

Towards a Regional Registry of Extended Typed Blood Donors: Molecular Typing for Blood Group, Platelet and Granulocyte Antigens

Towards a Regional Registry of Extended Typed Blood Donors: Molecular Typing for Blood Group, Platelet and Granulocyte Antigens

Insights intoanti‐Dformation in carriers ofRhDvariants through studies of3Dintraprotein interactions

It's time to phase out “serologic weak D phenotype” and resolve D types with RHD genotyping including weak D type 4

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