Genes Associated with Alloimmunization to Blood Group Antigens in Sickle Cell Disease

Abstract BACKGROUND: Alloimmunization to minor blood group antigens is more common in sickle cell disease (SCD) than in the general population. Causes include the high frequency of transfusion as well as phenotypic differences between the largely African-American SCD population and mostly Caucasian blood donors. Alloimmunization, as well as the risk of alloimmunization, results in higher costs as well as reduced availability of and delays in obtaining antigen-matched blood to meet clinical needs. We used a candidate gene approach to determine if specific genetic signatures were associated with alloimmunization and thus could identify patients at high risk for alloimmunization and therefore requiring prospective antigen matching for transfusion. METHODS: Patient data were previously collected through a multicenter study to identify genetic factors associated with SCD complications (Duke and UNC; DU) and through the Cooperative Study of SCD (CSSCD). All subjects were adults with HbSS genotype (DU mean yrs 34.9 ± 12.1, CSSCD mean yrs 29.1 ± 9.5, p < .0001). The DU data set was 43.7% male while the CSSCD data set was 37.1% male (p = .18). A genome-wide association study (GWAS) was conducted with the Illumina 610 BeadChips for 390 individuals (215 DU, 175 CSSCD). Quality control processing of these data was published previously (Solovieff et al, 2010). Additionally, imputation of the DU data set was conducted using IMPUTE2 (Howie et al, 2009) and a global reference panel from 1000 Genomes in order to have consistent genotypes across both studies. Based on previous literature, we studied 255 SNPs in the HLA locus as well as 684 SNPs in 53 genes previously associated with immune responses, totaling 939 SNPs. Additive logistic regression was performed separately for the DU and CSSCD data sets with PLINK (Purcell et al, 2008), controlling for age at enrollment. Results from the two data sets were combined by meta-analysis, using the invariance weight method in METAL (Willer et al, 2010). False discovery rate (FDR) q-values were generated using PROC MULTTEST in SAS v9.4 (SAS Systems). Contingency tables were produced using SAS and association between candidate SNPs and specific antibodies was tested using PLINK. RESULTS: Alloimmunization rates were different in the DU and CSSCD cohorts (30.7% vs. 18.9%, respectively; p = .0075) but were not associated with age or number of transfusions > 0 in either cohort. The most significant genetic associations with alloimmunization (FDR q = .28) occurred for 46 SNPs in the HLA locus and 10 other genes (Table 1). Two of these SNPs were missense mutations in GZMB (granzyme B (granzyme 2, cytotoxic T-lymphocyte-associated serine esterase 1)), one of which (rs8192917) has previously been associated with acute kidney transplant rejection and acute GVHD after stem cell transplant. A missense mutation in TRIM31 (E3 ubiquitin-protein ligase) was also associated with alloimmunization (p = .01). TRIM31 regulates Src-induced anchorage-independent cell growth and has been implicated in antiretroviral defense, cancer and ADHD. Within the DU cohort, we conducted a sub-analysis among only antigen-negative individuals, in whom immunization rates were 15.8%, 14%, 4.5%, 10.2%, 11%, and 8.3% to E, C, K, S, Jkb and Fya, respectively. Regression analysis of all 939 SNPs identified nominally significant associations predicting specific antibody alloimmunization. A missense mutation in PRKCQ (rs2236379) was associated with both anti-E and –C alloimmunization. Additional missense mutations were identified as follows: in TGFBR3 and GZMB with anti-C; in CFH, andTLR6 with anti-K, and in TLR10 with anti-Jkb. CONCLUSIONS: We have identified several immune response genes that are also associated with increased risk of alloimmunization in SCD (nominal p ≤ .006, FDR q = .28). Some associations may arise from the prevalence of alloimmunization to specific antigens. For example, PRKCQ was associated with development of alloantibodies to both E and C antigens, which reside on the same nonglycosylated RH protein. Expanded studies may identify those patients who would benefit from intensive or specific antigen-matching transfusion protocols. TableGenes Associated with AlloimmunizationGene or Locus (ordered by descending p value)SNPs with FDR q = 0.28 SNPs with p ≤ .006GZMB3 (2 missense)3TGFBR242TLR311HLA locus262TGFBR332PRKCQ3CD801VAV21TRIM312 (1 missense)RNF391ZNRD11 Disclosures No relevant conflicts of interest to declare.

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Implementation of a Standard Order Set at a Sickle Cell Acute Care Observation Unit

Blood ◽

10.1182/blood-2019-130877 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3396-3396

Author(s):

Renee Cheng ◽

Rishi Patel ◽

Sandra Kang ◽

Frances Tian ◽

Xu Zhang ◽

...

Keyword(s):

Pain Management ◽

Sickle Cell Disease ◽

Length Of Stay ◽

Acute Care ◽

Sickle Cell ◽

Research Funding ◽

Mixed Effects ◽

Data Sets ◽

Cell Disease ◽

Data Set

I NTRODUCTION: Acute painful vaso-occlusive crises (VOC) in sickle cell disease (SCD) are the leading cause of emergency department (ED) encounters and frequent hospital admissions. For patients presenting with an uncomplicated VOC, acute care observation units (ACOU) have previously been shown to reduce admission rates and length of stay. We wished to evaluate if implementing a standardized acute care order set (ACOS) at the University of Illinois Hospital Sickle Cell ACOU would decrease the time to first dose of analgesic medication, inpatient hospital stays, and subsequent admissions to the ACOU. METHODS: The ACOS includes standard orders for laboratory tests to monitor severity of sickle cell hemolysis, intravenous fluids, and analgesic medications including opioids. We conducted a retrospective analysis to evaluate if the ACOS enhanced workflow and improved the timeliness of treatment in patients experiencing a VOC. The ACOS was created in April 2017 and we compiled data from the three months before (January-March 2017) and after (May-July 2017) ACOS creation. We collected data on the time it took to administer the first opioid dose, admission rate, length of stay, number of acute care visits, ED visits, and inpatient hospitalizations in a three-month span, and demographics including variations in age, gender, and sickle cell disease genotype. Patient data was collected from a pharmacy-generated list of patients who received narcotics in the ACOU during the aforementioned time period. We analyzed the effect of the ACOS on the aforementioned variables. A mixed effects linear model was used to compare time to first dose of opioids and length of stay between data sets. A mixed effects logistic model was used for binary outcomes. Covariates of age (years), gender, and severity of sickle cell hemoglobin genotype (severe: HbSS, HbS beta0 thalassemia; mild: HbSC, HbS beta+ thalassemia) were included in the models. Statistical analyses were carried out in R version 3.4.3. DISCUSSION: The pre-ACOS data set contains 291 patient encounters for 76 patients with a median age of 37 years (interquartile range [IQR], 30-47 years), 66% female, and 71% with severe genotypes. The post-ACOS data set contained 289 patient encounters for 80 patients with a median age of 32 years (IQR, 27-45 years), 80% female, and 73% with severe genotypes. Implementation of an ACOS was associated with decreased time to pain management by 3.7 minutes (p=0.077) in patients presenting with uncomplicated VOC and with fewer repeat visits to the ACOU in the studied 3-month period [OR 0.35 (95% CI 0.13-1.00), p=0.049]. The median number of opiate doses received by patients in both data sets was 3. Using 3 as a cutoff, the implementation of the ACOS was also associated with more patients receiving >3 doses of opiates [OR=1.84 (95% CI 1.05-3.19), p = 0.033]. We demonstrate that in SCD patients experiencing VOC, a standardized ACOS was associated with a trend to reducing time to receiving pain management, with increased total opioid doses during the ACOU admission (suggesting better pain control), and subsequently with a statistically significant reduction in the number of repeat ACOU visits in the studied 3-month period. We have shown that a standardized ACOS that streamlines workflow in an ACOU may play an important role in delivering timely and quality care to patients with SCD. Disclosures Gordeuk: Pfizer: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Global Blood Therapeutics: Consultancy, Honoraria, Research Funding; Modus Therapeutics: Consultancy, Honoraria; Ironwood: Research Funding; CSL Behring: Consultancy, Honoraria, Research Funding; Imara: Research Funding; Inctye: Research Funding; Inctye: Research Funding; Pfizer: Research Funding; Emmaus: Consultancy, Honoraria; CSL Behring: Consultancy, Honoraria, Research Funding; Ironwood: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Imara: Research Funding; Modus Therapeutics: Consultancy, Honoraria.

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Potential Benefits of Extended Genotype Matching to Chronically Transfused Patients with Sickle Cell Disease

Blood ◽

10.1182/blood.v118.21.2144.2144 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2144-2144 ◽

Cited By ~ 1

Author(s):

Ricardo Helman ◽

Rodolfo Cancado ◽

Mariza A Mota ◽

Marcia R Dezan ◽

Jose Mauro Kutner ◽

...

Keyword(s):

Sickle Cell Disease ◽

Blood Group ◽

Sickle Cell ◽

Conflicts Of Interest ◽

Blood Group Antigens ◽

Cell Disease ◽

True Blood ◽

Erythrocyte Antigen ◽

Antibody Specificities

Abstract Abstract 2144 Background: Management of RBC alloimmunization in Sickle Cell Disease (SCD) patients has been the subject of much debate, and currently there is no standard approach. Many programs transfuse SCD patients with RBCs that are phenotype-matched for D, C, c, E, e and K. Although these approaches reduce the incidence of alloantibody production, patients still become alloimmunized. Based on this we aimed to identify the rates of alloimmunization in chronically transfused SCD patients and compare the phenotyping with genotyping methods to find a better way to match RBC units to those patients. Methods: We selected 45 SCD patients (homozygous for hemoglobin S) with multiple transfusions, previously phenotyped for ABO, Rh (D, C, c, E, e) and K1. Phenotypes were determined by hemagglutination using gel cards (Diamed® ). Genotypes were determined by a DNA array using the Human Erythrocyte Antigen BeadChip (“HEA”) from Bioarray Solutions. All SCD patients included in this study were in chronical transfusion program; receiving multiple transfusions. The median age was 24y; there were 28(62%) females and 17(37.8%) males. The median of transfusions were 53 (5–78) and 40 (88.9%) patients received more than 20 phenotype-matched units for Rh (D, C, c, E, e) and K1. Results: Of the 45 SCD patients selected, 11 (24.4%) had alloantibodies. The antibody specificities found in these patients were anti-D, -C, -CW, -E, -Jka, -Jkb, -Fya, -Dia, -s. Although the patients were receiving Rh and K phenotype-matched units 8 (17%) of them became alloimmunized to Rh antigens and on those patients we found discrepancies between the previous phenotype and genotype-derived phenotype. Our results showed that the risk of immunization increases in patients over 40 years old (p= 0.05) and with the number of transfusion events. Patients with more than 20 RBC transfusions have a tendency for alloimmunization (p=0.65). We also observed that genotyping was more effective than hemagglutination in determining patient's correct phenotype. Conclusion: Our data show that even with the implementation of Rh and K phenotype-matching in chronically transfused patients with SCD, they still become alloimmunized to other antigens with high immunization risk and also to Rh antigens due to the limitations of the hemagglutination. The relevance of genotype determination of blood groups for the management of multiple transfused patients with SCD has been demonstrated by allowing the determination of the true blood group genotype, by assisting in the identification of suspected alloantibodies and in the selection of antigen-negative. As donor genotyping for the most clinically relevant blood group antigens by automated DNA techniques are becoming available, extended genotype matching should be considered in this group of patients. Disclosures: No relevant conflicts of interest to declare.

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Use of Genomics for Transfusion Therapy Management in Patients with Sickle Cell Disease

Blood ◽

10.1182/blood.v118.21.2324.2324 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2324-2324

Author(s):

Connie M Westhoff ◽

Stella T Chou ◽

Kim Smith-Whitley ◽

David Friedman

Keyword(s):

Sickle Cell Disease ◽

Blood Group ◽

Sickle Cell ◽

Conflicts Of Interest ◽

Hla Typing ◽

Blood Group Antigens ◽

Dna Testing ◽

Cell Disease ◽

Transfusion Therapy ◽

Clinically Significant

Abstract Abstract 2324 A genomic approach to blood group typing is now possible and high-throughput automated platforms have been developed to test for numerous blood group antigens in a single assay. These methods are reproducible and highly correlated with RBC serologic phenotype. We routinely perform a complete RBC phenotype for clinically significant minor red cell antigens on pre-transfusion samples from patients with sickle cell disease, and we antigen match patients for C, E, and K for transfusion. In this study we compared the historic serologic typing with that predicted from DNA testing for clinically significant antigens in 114 samples from chronically transfused patients with SCD to determine concordance and to evaluate the clinical utility of genotyping for the management of transfusion therapy. Serologic typing was performed by standard methods with licensed commercial reagents. DNA was isolated from WBCs, and minor antigen genotyping was performed with HEA (human erythrocyte antigen) BeadChip (BioArray, Inc). RH genotyping was by a combination of methods including PCR-RFLP, AS-PCR, exon-specific amplification and sequencing, and, for some, Rh-cDNA amplification and sequencing. Comparison of serologic typing with DNA-based testing for thirteen blood group antigens, CcEe, Fya/b, K, Jka/b, MN and Ss, in 114 samples found 8 discrepancies in 1,482 antigens analyzed, for 99.5 % concordance. Discrepancies were in several systems (C, Fy, Ss, and M), and at least one has been confirmed to be a serologic recording error. All are under investigation. DNA-based testing for RH found 54 of 114 patients inherited variant RHD alleles; many also had conventional RHD in trans. Sixteen patients had made anti-D, despite typing as D+. Ten of 35 patients (∼30%) whose RBCs typed as C+ had a hybrid allele encoding variant C antigen. Five had made anti-C, which prompted us to change our protocol so patients with variant C by DNA testing are transfused on a C- protocol. DNA testing found a large amount of diversity in ce-alleles in this population. Seventy-two of 114 patients carried at least one of nine different variant ce-alleles. Ten patients had made anti-e, despite typing as e+, and were homozygous for variant ce-alleles. In total, 49/114 patients with SCD were homozygous for variant RH alleles and were not truly Rh matched for D, C and e antigens by serology. Similar to the way in which HLA typing by DNA has revolutionized bone marrow transplantation by providing a superior alternative to serological testing, we find that minor blood group antigen typing by DNA improves efficiency, reduces cost, and expands antigen matching, especially in the Rh system. Continuing studies are needed to identify more precisely which variant alleles are associated with clinically significant antibody production to improve antigen matching for patients with sickle cell disease. Disclosures: No relevant conflicts of interest to declare.

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High-Throughput DNA Analysis for Red Blood Cell Antigens Facilitates the Transfusion Support with Antigen-Matched Blood in Sickle Cell Disease Patients.

Blood ◽

10.1182/blood.v106.11.555.555 ◽

2005 ◽

Vol 106 (11) ◽

pp. 555-555

Author(s):

Lilian Castilho ◽

Ghazala Hashmi ◽

Marion E. Reid ◽

Tasmia Shariff ◽

Michael Seul ◽

...

Keyword(s):

Sickle Cell Disease ◽

Blood Group ◽

Sickle Cell ◽

High Throughput ◽

Dna Analysis ◽

Blood Type ◽

Blood Group Antigens ◽

Nucleotide Polymorphisms ◽

Cell Disease ◽

Fast Procedure

Abstract Background: Transfusion dependent patients as those with Sickle Cell Disease (SCD) patients become alloimmunized and have the potential to form additional antibodies with such frequency that antigen-negative blood is preferred to prevent further alloimmunization. Blood group genotyping is playing a supporting role in the routine blood banks, especially for provision of antigen-matched blood for these patients. However, current techniques for genomic typing are all labor-intensive and require manual set up and analysis by gel electrophoresis. As a result, DNA microarrays are being developed for the single nucleotide polymorphisms (SNPs) detection in the blood group genes to provide a fast procedure and an automated analysis of numerous blood group polymorphisms. We evaluated the usefulness of DNA microarray to provide a means to precisely match donor blood to the antigen-negative type of SCD patients. Method: A total of 12 DNA samples from patients with SCD (homozygous for HbS) and 84 DNA samples from blood donors, were analyzed by the HEA Beadchip (Hashmi et al, 2005) containing a total of 18 SNPs (FYA/B, FY-GATA, FY265, DOA/B (nt 378, 624, 793), COA/B, LWA/B, DIA/B, SC1/SC2, M/N, S/s, LUA/B, KEL1/2, JKA/B, DO323, DO350, HgbS) in a single reaction. Results: A genotype result was obtained for all SNPs tested on 96 samples within 4 hours of the start of testing. Results obtained by Beadchip analysis in donors were used to provide antigen-matched blood for FYA/B, FY-GATA, FY265, DOA/B, M/N, S/s KEL1/2, JKA/B, for all 12 SCD patients. This technology provided a fast procedure and facilitated the transfusion support with antigen-matched blood in SCD patients allowing the reduction of alloimunization to blood group antigens. Conclusion: This high-throughput DNA analysis has the potential not only to increase the inventory of antigen-negative blood but also to facilitate the matching of RBC component to the recipient’s blood type. It also contributes to the management of transfusions in SCD patients by allowing a more accurate selection of donor units. The application of microarray technology in transfusion medicine may have a tremendous impact on further improvement of the safety of blood transfusion.

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Characterization and statistical modeling of glycosylation changes in sickle cell disease

Blood Advances ◽

10.1182/bloodadvances.2020003376 ◽

2021 ◽

Vol 5 (5) ◽

pp. 1463-1473

Author(s):

Heather E. Ashwood ◽

Christopher Ashwood ◽

Anna P. Schmidt ◽

Rebekah L. Gundry ◽

Karin M. Hoffmeister ◽

...

Keyword(s):

Mass Spectrometry ◽

Sickle Cell Disease ◽

Blood Cell ◽

Red Blood Cells ◽

Blood Group ◽

Sickle Cell ◽

Red Blood Cell ◽

Blood Cells ◽

Blood Group Antigens ◽

Cell Disease

AbstractSickle cell disease is an inherited genetic disorder that causes anemia, pain crises, organ infarction, and infections in 13 million people worldwide. Previous studies have revealed changes in sialic acid levels associated with red blood cell sickling and showed that stressed red blood cells bare surface-exposed clustered terminal mannose structures mediating hemolysis, but detailed glycan structures and anti-glycan antibodies in sickle cell disease remain understudied. Here, we compiled results obtained through lectin arrays, glycan arrays, and mass spectrometry to interrogate red blood cell glycoproteins and glycan-binding proteins found in the plasma of healthy individuals and patients with sickle cell disease and sickle cell trait. Lectin arrays and mass spectrometry revealed an increase in α2,6 sialylation and a decrease in α2,3 sialylation and blood group antigens displayed on red blood cells. Increased binding of proteins to immunogenic asialo and sialyl core 1, Lewis A, and Lewis Y structures was observed in plasma from patients with sickle cell disease, suggesting a heightened anti-glycan immune response. Data modeling affirmed glycan expression and plasma protein binding changes in sickle cell disease but additionally revealed further changes in ABO blood group expression. Our data provide detailed insights into glycan changes associated with sickle cell disease and refer glycans as potential therapeutic targets.

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ECMO Therapy in Acute Chest Syndrome for Patients with Sickle Cell Disease: a Case Report and Literature Review

SN Comprehensive Clinical Medicine ◽

10.1007/s42399-021-00987-0 ◽

2021 ◽

Author(s):

Soi Avgeridou ◽

Ilija Djordjevic ◽

Anton Sabashnikov ◽

Kaveh Eghbalzadeh ◽

Laura Suhr ◽

...

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Scientific Data ◽

Acute Chest Syndrome ◽

Data Sets ◽

Limited Data ◽

Cell Disease ◽

Life Saving ◽

Institutional Experience ◽

Ecmo Therapy

AbstractExtracorporeal membrane oxygenation (ECMO) plays an important role as a life-saving tool for patients with therapy-refractory cardio-respiratory failure. Especially, for rare and infrequent indications, scientific data is scarce. The conducted paper focuses primarily on our institutional experience with a 19-year-old patient suffering an acute chest syndrome, a pathognomonic pulmonary condition presented by patients with sickle cell disease. After implementation of awake ECMO therapy, the patient was successfully weaned off support and discharged home 22 days after initiation of the extracorporeal circulation. In addition to limited data and current literature, further and larger data sets are necessary to determine the outcome after ECMO therapy for this rare indication.

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RH genotyping in a sickle cell disease patient contributing to hematopoietic stem cell transplantation donor selection and management

Blood ◽

10.1182/blood-2010-04-279372 ◽

2010 ◽

Vol 116 (15) ◽

pp. 2836-2838 ◽

Cited By ~ 26

Author(s):

Ross M. Fasano ◽

Alessandro Monaco ◽

Emily Riehm Meier ◽

Philippe Pary ◽

A. Hallie Lee-Stroka ◽

...

Keyword(s):

Stem Cell ◽

Sickle Cell Disease ◽

Stem Cell Transplantation ◽

Cell Transplantation ◽

Blood Group ◽

Sickle Cell ◽

Disease Patient ◽

Nucleotide Sequencing ◽

Cell Disease ◽

Hematopoietic Stem

Abstract African individuals harbor molecular RH variants, which permit alloantibody formation to high-prevalence Rh antigens after transfusions. Genotyping identifies such RH variants, which are often missed by serologic blood group typing. Comprehensive molecular blood group analysis using 3 genotyping platforms, nucleotide sequencing, and serologic evaluation was performed on a 7-year-old African male with sickle cell disease who developed an “e-like” antibody shortly after initiating monthly red blood cell (RBC) transfusions for silent stroke. Genotyping of the RH variant predicted a severe shortage of compatible RBCs for long-term transfusion support, which contributed to the decision for hematopoetic stem cell transplantation. RH genotyping confirmed the RH variant in the human leukocyte antigen–matched sibling donor. The patient's (C)ces type 1 haplotype occurs in up to 11% of African American sickle cell disease patients; however, haplotype-matched RBCs were serologically incompatible. This case documents that blood unit selection should be based on genotype rather than one matching haplotype.

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RH Gene Polymorphisms Are Risk Factor for Alloimmunization in Patients with Sickle Cell Disease.

Blood ◽

10.1182/blood.v110.11.455.455 ◽

2007 ◽

Vol 110 (11) ◽

pp. 455-455 ◽

Cited By ~ 1

Author(s):

Connie M. Westhoff ◽

Sunitha Vege

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Cost Effective ◽

Blood Group Antigens ◽

Cell Disease ◽

Negative Effects ◽

Transfusion Therapy ◽

Risk Patients ◽

Patient Groups ◽

Red Cell Transfusion

Abstract Transfusion therapy for treatment of sickle cell disease (SCD) is predicted to increase, following the significant benefit of chronic red cell transfusion demonstrated by the stroke prevention trial (STOP). Despite progress in mitigating negative effects of transfusion therapy with the use of iron chelating agents, alloimmunization remains a significant problem. Patients with SCD have a higher incidence of antibody production compared to other patient groups undergoing chronic transfusion. To limit alloimmunization, many programs transfuse SCD patients with RBCs that are phenotype-matched for the most immunogenic blood groups, Rh and K, and some programs also supply RBCs from African-American (AA) donors. Although this approach reduces the incidence of alloantibody production, it is resource- and cost-prohibitive for many programs, and, importantly, some patients (∼5%) still become alloimmunized. The development of high-throughput genotyping for blood group antigens will make antigen-matching cost effective; therefore, it is important to determine why some patients become alloimmunized despite antigen-matching. We investigated the antibody specificity and sequenced the RH genes in 46 SCD patients who were alloimmunized, despite having received Rh and K matched units. The antibodies identified included anti-D, or -C, or -e, and/or antibodies to high-prevalence antigens. None had anti-E. RH gene sequencing revealed that 20 patients had a RHD-CE(3–7)-D hybrid gene in which RHD exons 3 through 7 are replaced with reciprocal exons from RHCE. The resulting Rh protein encodes an altered C antigen. This D-CE-D gene was also linked to an RHce allele encoding altered e antigen. These patients had anti-C and/or anti-e in their serum (i.e.-hrB). We screened healthy AA donors and found that the prevalence of the hybrid RHD-CE(3–7)-D gene in this population is 5–8%. The remaining 26 patients were homozygous for mutations in RHce and had produced anti-e, and some also had mutations in RHD and had produced anti-D. These results suggest that inheritance of a RHD-CE-D gene or altered RHce, with or without altered RHD, underlies Rh alloimmunization in SCD. The altered Rh proteins are not distinguished with current serologic typing reagents. Therefore, these patients are not truly Rh antigen matched. The development of RH genotyping platforms offers a potential solution to prevent alloimmunization by identifying SCD patients who are homozygous for variant alleles and at risk for production of alloantibodies to Rh antigens. The 5–8% of donor units with the same RH genotype could be directed to these high risk patients.

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Polymorphisms in TNFα Are Associated with Cerebrovascular Events in Sickle Cell Disease.

Blood ◽

10.1182/blood.v114.22.1540.1540 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1540-1540 ◽

Cited By ~ 1

Author(s):

Latorya A Barber ◽

Allison E Ashley-Koch ◽

Melanie E. Garrett ◽

Karen L Soldano ◽

Marilyn J. Telen

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Conflicts Of Interest ◽

Umbilical Vein ◽

Acute Chest Syndrome ◽

Cell Disease ◽

Data Set ◽

Clinical Complications ◽

Cerebrovascular Events ◽

Increased Risk

Abstract Abstract 1540 Poster Board I-563 Tumor necrosis factor alpha (TNFα) is a pro-inflammatory cytokine that stimulates phagocytosis, neutrophil recruitment, and expression of adhesion molecule VCAM-1. Plasma levels of TNFα have been found to be increased in sickle cell disease (SCD), and in vitro studies show that TNFα causes increased adherence of sickle red blood cells to human umbilical vein endothelial cells. A polymorphism in the promoter region of the TNFα gene has previously been associated with stroke in children with SCD (Hoppe et al., 2007). The current study was designed to identify associations of additional TNFα single nucleotide polymorphisms (SNPs) with SCD clinical complications. We analyzed five SNPs in the TNFα gene in 509 DNA samples of SCD patients from Duke University, University of North Carolina at Chapel Hill, and Emory University. In our data set, cerebrovascular events (CVEs), including overt stroke, seizures, and transient ischemic attacks, occurred in 133 out of 509 SCD patients (26.1%). SNP genotyping was performed using Taqman genotyping assays from Applied Biosystems. Due to low minor allele frequencies (<0.05) for all the SNPs examined, genetic associations with SCD clinical complications were examined by using allele tests. After controlling for age, gender, and use of hydroxyurea, two of the five TNFα SNPs, rs2228088 and rs3093665, were significantly associated with CVEs (p=0.013 and 0.029, respectively). The odds that SCD patients with a G allele at rs2228088 suffered from CVEs were 0.485 times that for patients with the T allele, suggesting that the G allele had a protective effect. The odds of having the A allele at rs3093665 and suffering from CVEs was also reduced, at 0.45 compared to the C allele. Neither SNP was found to be in linkage disequilibrium (LD) with any of the other SNPs analyzed (r2≤0.002). There was also strong association of SNP rs2228088 with acute chest syndrome (ACS; p=0.003), occurring in 382 out of 509 SCD patients (75%). However, in this analysis, the G allele was associated with increased risk for ACS (OR=2.313). In addition to the association with CVEs, the SNP rs3093665 was also significantly associated with priapism (p=0.03), reported by 86 of 223 male SCD patients (38.6%). In this analysis, the A allele was protective, as had been observed for CVE (OR=0.188). Additionally, we found no difference in steady state plasma TNFα levels between genotypes for the two SNPs. The functional significance of these SNPs is presently unknown. SNP rs2228088 is a synonymous SNP located in the coding region, and rs3093665 is located in the 3' untranslated region of the TNFα gene. While the G to T change at SNP rs2228088 does not translate to a change in amino acid sequence, the A to C change at SNP rs3093665 may affect mRNA stability due to its location. It is also possible that one or both of these SNPs is in LD with another functionally relevant SNP. Our findings thus support previous data implicating TNFα polymorphisms in risk for central nervous system events. Interestingly, ACS has been previously associated with seizures, stroke and altered mental status in adults and children with SCD (Vinchinsky et al., 2000) and with silent cerebral infarcts and reversible posterior leukoencephalopathy syndrome in children with SCD (Henderson et al., 2003). However, in our dataset, ACS and the occurrence of CVEs were not associated (p=0.24). Further studies are required to elucidate these and other factors that potentially correlate with SCD clinical complications. Disclosures No relevant conflicts of interest to declare.

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Genetic Variation In MYH9 Is Associated with Sickle Cell Disease Nephropathy

Blood ◽

10.1182/blood.v116.21.1648.1648 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1648-1648

Author(s):

Emmanuel Okocha ◽

Melanie Garrett ◽

Karen Soldano ◽

Laura M. De Castro ◽

Jude Jonassaint ◽

...

Keyword(s):

High Risk ◽

African Americans ◽

Sickle Cell Disease ◽

Renal Dysfunction ◽

Sickle Cell ◽

Heavy Chain ◽

Multiple Testing ◽

Risk Haplotype ◽

Cell Disease ◽

Data Set

Abstract Abstract 1648 Background: Renal failure occurs in 5–18% of sickle cell disease (SCD) patients and is a major risk factor for early mortality. However, there is no established method of identifying SCD patients that are at high risk of developing this outcome prior to the appearance of proteinuria, and its pathobiology is not well understood. The non-muscle myosin heavy chain ll-A (MYH9) gene, which encodes the heavy chain of myosin II-A in the podocyte cytoskeleton, has been identified as driving the high risk of focal segmental glomerulosclerosis (FSGS) and end-stage renal disease in African Americans. Methods: We genotyped 26 single nucleotide polymorphisms (SNPs) in the MYH9 gene in 521 unrelated adult (18 – 83 years) SCD patients who had been screened for proteinuria. Logistic regression was used to determine if the SNPs predicted risk for proteinuria among the patients. Results: Of 521 adult SCD patients studied, 140 had proteinuria, while 381 did not. On average, subjects with proteinuria were 6 years older than subjects without proteinuria (p<0.0001). The odds of having proteinuria increased by 1.04 (4.2%) for every one year increase in age, starting at age 18. We found association with proteinuria for 8 SNPs in MYH9, with nominal p values ranging from 0.025 to 0.0001. Two of these SNPs (rs5756129 and rs1005570) had been previously associated with FSGS in African-Americans without SCD (Kopp et al., 2008). Five SNPs remained significant after correcting for multiple testing (p < 0.003) using the method described by Li and Ji (2005), and a risk haplotype significantly associated with proteinuria (p=0.001) was identified. The frequency of proteinuria among individuals who were homozygous for the risk genotype ranged from 40–50% for each of the five SNPs remaining significant after adjusting for multiple testing, while the risk of proteinuria for individuals who did not have that genotype ranged from 20–30%. Glomerular filtration rate was negatively correlated with proteinuria (r = -0.25, p < 0.0001) but was not itself associated with MYH9 SNPs. Although we tested for association of proteinuria with the two most significant BMPR1B SNPs found by Nolan et al. (2007), neither were associated with proteinuria or GFR in age-adjusted analysis of our cohort, although we did observe nominal evidence for association of a different BMPR1B SNP with proteinuria in our data set (rs1434536, p=0.004, age adjusted). To further investigate a possible connection between BMPR1B and MYH9, we performed regression analyses including BMPR1B SNPs (rs1434536, rs2240036 and rs4145993) and the MYH9 haplotype in the models and controlled for age. In these analyses, the MYH9 risk haplotype remained a significant predictor of proteinuria and was only borderline associated with GFR. None of the BMPR1B SNPs were associated with proteinuria or GFR when the MYH9 haplotype was included in the model, suggesting that MYH9 is likely the more important contributor to these processes in our data set. Conclusion: Our data provide additional support for the role of MYH9 in renal dysfunction among African Americans. A specific haplotype appears to be associated with increased risk for proteinuria among patients with SCD. The association of MYH9 with renal dysfunction in SCD provides insight into the pathophysiology of this process and may lead to early identification of patients at risk and, ultimately, to new modes of therapeutic intervention. Disclosures: De Castro: GlycoMimetics: . Telen:GlycoMimetics: Consultancy, clinical trial sponsorship.

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