The protean presentations of XK disease (McLeod syndrome): a case series with new observations and updates on previously reported families.

XK disease is a very rare, multi-system disease, which can present with a wide spectrum of symptoms. This disorder can also be identified pre-symptomatically with the incidental detection of serological abnormalities when typing erythrocytes in peripheral blood, or on other routine laboratory testing. Increasing awareness of this disorder and improved access to genetic testing are resulting in increasing identification of affected patients and families.

Genotyped RhD+ red cells for D-positive patients with sickle cell disease with conventional RHD and unexpected anti-D.

Anti-D can occur in D-positive patients who inherit RHD genetic variants encoding partial D antigen expression, but unexpected anti-D is also found in the plasma of patients with sickle cell disease who have conventional RHD gene(s) and are transfused with units from Black donors. These anti-D are likely stimulated by variant Rh expressed on donor cells; however, patients with anti-D, regardless of cause, are transfused for a lifetime with D-negative (Rh-negative) blood. This results in significant increased use of Rh-negative units, especially for those requiring chronic transfusion, which can strain Rh-negative blood inventories.

Blood group genotype matching for transfusion.

The last decade has seen significant growth in the application of DNA-based methods for extended antigen typing, and the use of gene sequencing to consider variation in blood group genes to guide clinical care. The challenge for the field now lies in educating professionals, expanding accessibility and standardizing the use of genotyping for routine patient care. Here we discuss applications of genotyping when transfusion is not straightforward including when compatibility cannot be demonstrated by routine methods, when Rh type is unclear, when allo- and auto-antibodies are encountered in stem cell and organ transplantation, for prenatal testing to determine maternal and foetal risk for complications, and Group A subtyping for kidney and platelet donors.

Three novel Er blood group system alleles and insights from protein modeling.

Background: The Er blood group system was recently shown to be defined by PIEZO1. The system consists of high prevalence antigens Er, Er3, ERSA, and ERAMA; and low prevalence antigen Er. Er/Er are antithetical with Er(a-b+) defined by the ER*B allele [c.

Machine learning to optimize automated RH genotyping using whole-exome sequencing data.

Rh phenotype matching reduces but does not eliminate alloimmunization in patients with sickle cell disease (SCD) due to RH genetic diversity that is not distinguishable by serological typing. RH genotype matching can potentially mitigate Rh alloimmunization but comprehensive and accessible genotyping methods are needed. We developed RHtyper as an automated algorithm to predict RH genotypes using whole-genome sequencing (WGS) data with high accuracy.

BMI1 regulates human erythroid self-renewal through both gene repression and gene activation.

The limited proliferative capacity of erythroid precursors is a major obstacle to generate sufficient numbers of in vitro-derived red blood cells (RBC) for clinical purposes. We and others have determined that BMI1, a member of the polycomb repressive complex 1 (PRC1), is both necessary and sufficient to drive extensive proliferation of self-renewing erythroblasts (SREs). However, the mechanisms of BMI1 action remain poorly understood.

RH genotypes and red cell alloimmunization rates in chronically transfused patients with sickle cell disease: A multisite study in the USA.

Background: Red cell alloimmunization remains a challenge for individuals with sickle cell disease (SCD) and contributes to increased risk of hemolytic transfusion reactions and associated comorbidities. Despite prophylactic serological matching for ABO, Rh, and K, red cell alloimmunization persists, in part, due to a high frequency of variant RH alleles in patients with SCD and Black blood donors.

Study Design And Methods: We compared RH genotypes and rates of alloimmunization in 342 pediatric and young adult patients with SCD on chronic transfusion therapy exposed to >90,000 red cell units at five sites across the USA.

Variant RHD alleles and Rh immunization in patients with sickle cell disease.

RH diversity among patients and donors contributes to Rh immunization despite serologic Rh-matched red cell transfusions. Anti-D can occur in D+ patients with RHD variants that encode partial D antigens. Anti-D has also been reported in patients with conventional RHD transfused primarily with units from Black donors who frequently have variant RHD.

A novel high-prevalence antigen in the Lutheran system, LUGA (LU24), and an updated, full-length 3D BCAM model.

Background: The basal cell adhesion molecule (BCAM) carries the antigens of the Lutheran (LU, ISBT005) system. We report a novel Lutheran antigen and propose an updated, full-length 3D model of BCAM.

Study Design And Methods: Red blood cell testing, antibody identification, and BCAM genomic DNA sequencing were done by standard methods.

ABO Genotyping finds more A to B kidney transplant opportunities than lectin-based subtyping.

ABO compatibility is important for kidney transplantation, with longer waitlist times for blood group B kidney transplant candidates. However, kidneys from non-A (eg, A) subtype donors, which express less A antigen, can be safely transplanted into group B recipients. ABO subtyping is routinely performed using anti-A lectin, but DNA-based genotyping is also possible.

Two new Scianna variants causing loss of high prevalence antigens: ERMAP model and 3D analysis of the antigens.

Background: Scianna (Sc) antigens, seven high and two of low prevalence, are expressed on erythrocyte membrane-associated protein (ERMAP). We investigated SC (ERMAP) in individuals who made antibodies to high prevalence Scianna antigens, and propose a 3D model for ERMAP to precisely localize the residues associated with the known antigens.

Methods: Serological testing and DNA sequencing was performed by standard methods.

The use of pluripotent stem cells to generate diagnostic tools for transfusion medicine.

Red blood cell (RBC) transfusion is one of the most common medical treatments, with more than 10 million units transfused per year in the United States alone. Alloimmunization to foreign Rh proteins (RhD and RhCE) on donor RBCs remains a challenge for transfusion effectiveness and safety. Alloantibody production disproportionately affects patients with sickle cell disease who frequently receive blood transfusions and exhibit high genetic diversity in the Rh blood group system.

YTGT: A new high-prevalence antigen in the Yt blood group system in two unrelated Native Americans and transfusion management.

Background: The Yt system consists of five antigens: antithetical Yt /Yt and the high-prevalence antigens YTEG, YTLI, and YTOT. We investigated a sample from a Native American (NA) female with post-operative anemia and an unidentified antibody who developed rigors, tachycardia, and hypotension on transfusion of incompatible RBCs.

Methods And Materials: Serologic testing methods included LISS, PEG, and IgG gel.

Red Cell Antigens and Antibodies.

Autoimmune hemolytic anemia (AIHA) is caused by the production of "warm-" or "cold-" reactive autoantibodies directed against RBC antigens that may be of undefined specificity, reacting with all RBCs tested or may have an apparent specificity. Autoantibodies may be of IgG, IgM, or rarely IgA isotypes and their production can be triggered by disease, viral infection, or drugs; from breakdown in immune system tolerance to self-antigens; or from exposure to foreign antigens that induce antibodies that cross-react with self-RBC antigens. Increasingly, AIHA is being reported in patients following allogeneic hematopoietic stem cell transplantation and treatment with anti-cancer checkpoint inhibitors.

Accurate long-read sequencing allows assembly of the duplicated RHD and RHCE genes harboring variants relevant to blood transfusion.

Next-generation sequencing (NGS) technologies have transformed medical genetics. However, short-read lengths pose a limitation on identification of structural variants, sequencing repetitive regions, phasing of distant nucleotide changes, and distinguishing highly homologous genomic regions. Long-read sequencing technologies may offer improvements in the characterization of genes that are currently difficult to assess.