• Rh serologic phenotype-matched transfusions from minority donors do not prevent all Rh alloimmunization in patients with SCD.• Variant RH genes are common in patients with SCD and contribute to Rh alloimmunization and transfusion reactions.Red blood cell (RBC) transfusion is a key treatment of patients with sickle cell disease (SCD) but remains complicated by RBC immunization. In the present study, we evaluated the effects of antigen matching for Rh D, C, and E, and K and transfusion from African American donors in 182 patients with SCD. Overall, 71 (58%) chronic and 9 (15%) episodically transfused patients were alloimmunized. Fifty-five (45%) chronic and 7 (12%) episodically transfused patients were Rh immunized. Of 146 antibodies identified, 91 were unexplained Rh antibodies, one-third of which were associated with laboratory evidence of delayed transfusion reactions. Fifty-six antibodies occurred in patients whose RBCs were phenotypically positive for the corresponding Rh antigen and 35 in patients whose RBCs lacked the antigen and were transfused with Rh-matched RBCs. High-resolution RH genotyping revealed variant alleles in 87% of individuals. These data describe the prevalence of Rh alloimmunization in patients with SCD transfused with phenotypic Rh-matched African American RBCs. Our results suggest that altered RH alleles in both the patients and in the donors contributed to Rh alloimmunization in this study. Whether RH genotyping of patients and minority donors will reduce Rh alloimmunization in SCD needs to be examined. (Blood. 2013;122 (6):1062-1071

DNA-based RBC typing provided improved accuracy and expanded information on RBC antigens compared to hemagglutination methods, leading to its implementation as the primary method for extended RBC typing for patients with SCD at our institution.

Sickle cell disease (SCD) is a disorder known to impact the respiratory system. We sought to identify respiratory muscle force and lung volume relationships in a paediatric SCD population. Thirty-four SCD-SS subjects underwent pulmonary function testing. Height, weight, age, and gender-adjusted percent predicted maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) values were compared to spirometry and lung volumes. Statistical analyses were performed using Pearson’s correlation coefficient and paired two-tailed t-test. The mean ±standard deviation (SD) MIP and MEP was 69.6 ±31.6 cm H2O and 66.9 ±22.9 cm H2O, respectively, and mean ±SD percent predicted MIP (101.3 ±45.9) exceeded MEP (72.1 ±26.0) (p = 0.002). MIP correlated with forced vital capacity (FVC; r = 0.51, p = 0.001) and TLC (r = 0.54, p < 0.0001). MEP also correlated with FVC (r = 0.43, p = 0.011) and total lung capacity (TLC; r = 0.42, p = 0.013). Pearson’s correlation coefficient testing yielded relationships between MIP and MEP (r = 0.64, p < 0.0001). SCD-SS patients showed correlations between respiratory muscle force and lung volume, and reduced percent predicted expiratory muscle force compared to inspiratory muscle force. Respiratory muscle strength may affect lung volumes in these patients, and expiratory muscles may be more susceptible than the diaphragm to SCD-induced vaso-occlusive damage.

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Background Sickle cell disease (SCD) is an autosomal recessive hemoglobinopathy associated with morbidity and mortality. We sought to understand family planning intentions of parents of young children with SCD including the awareness of three reproductive options (adoption, in vitro fertilization with egg/sperm donation [IVFD], in vitro fertilization [IVF] with preimplantation genetic testing [IVF/PGT]) to decrease the risk of having a child with SCD. Procedure Qualitative, semistructured, one‐on‐one interviews with 18 female parents of young children with SCD at an urban, tertiary care pediatric hospital. Results Half of the parents knew their hemoglobinopathy status or their partner's status before pregnancy. Eight parents chose to have no further children because of fear of SCD in another child. Awareness of reproductive options prior to study enrollment was limited. After brief introduction, 7 parents would consider adoption, 2 IVFD, and 10 IVF/PGT. Desire for a biological child, fear of parental jealousy, ethical or religious considerations, and cost affected the acceptability of these options. Participants universally wanted information about reproductive options available to others prior to pregnancy. Conclusions There is limited awareness and variable acceptability of alternative reproductive options available to decrease the risk of a future child having SCD. Participants universally endorsed the need for education regarding hemoglobinopathy status, SCD, and reproductive options prior to pregnancy because for many participants having a child with SCD affected their reproductive intentions. Educational interventions to ensure informed reproductive decision making should be sensitive to desires for a biological child, and ethical and financial considerations.

BACKGROUND: Sickle Cell Disease (SCD) is an autosomal recessive hemoglobinopathy affecting 90-100,000 persons in the US and is associated with considerable morbidity and early mortality. Little is known regarding how having a child with SCD affects parents’ future reproductive decisions or acceptability of alternative family planning options. METHODS: We conducted semi-structured one-on-one interviews with parents of young children with SCD who are patients at The Children’s Hospital of Philadelphia. Interviews included open-ended questions regarding SCD, thoughts about their child’s SCD, family planning, attitudes about alternative reproductive options to decrease the risk of a future child having SCD (adoption, invitro fertilization with egg/sperm donations (IVFD), or IVF with preimplantation genetic diagnosis (IVF/PGD)), and advice to others. Inclusion criteria included being the biologic parent of a child with SCD, having 1 or 2 children younger than 6 years, and not being pregnant. We chose this time frame since parents may be more likely to be actively deciding on future children. Interviews were digitally recorded, transcribed, and analyzed by 2 reviewers. Interviews were conducted until thematic saturation of content was achieved. Analysis was based on a modified grounded theory. RESULTS: Twenty parents completed the interview, 18 were female. Twelve had children with SCD 2 years or younger. Fourteen had children with SS-type SCD, with the remaining having SC-type. The mean age of parents was 26.4 years (SD 6.4 years). Thirteen had educational attainment beyond high school. Nine held private medical insurance. Nineteen identified at black or African American. One half (n=10) knew their hemoglobinopathy status prior to pregnancy though only two knew their partner’s status. Four believed it was possible for them to have a child with SCD prior to having children. Regarding family planning, almost all describe SCD as genetic or inherited. Eight described actively decreasing the number of total children desired and eliminating future planned pregnancies, sighting fear of SCD as the main reason. In general, parents have positive and negative feelings regarding the possibility of SCD in a future child. Positive attributes to having a future child with SCD included the older sibling being a role model or support system and feeling more prepared. Negative attributes included anticipating a sense of regret or irresponsibility. Knowledge of alternative reproductive options to decrease the risk of SCD in a future child was limited with 5 parents responding with an option in open ended questioning. When asked about specific options, half of parents would consider using adoption, 2 for IVFD, and 11 for IVF/PGD. The most common themes in not considering these options were the desire for a biologic child (adoption, IVFD), fear of parental jealously (IVFD), and ethical and religious concerns (IVF/PGD). Other prominent themes that emerged included anxiety and hope regarding the future, the normalcy of their child, desire for information prior to pregnancy for others (general SCD information, personal, and partner status), and regret in lack of information known prior to pregnancy. CONCLUSIONS: This study expands our understanding of how having a child with SCD affects parents’ reproductive considerations. In general, there was a lack of knowledge of personal or partner SCD status prior to pregnancy. Many parents expressed a duality of emotion often combining regret for not knowing their status earlier and hope for their child. We noted variable knowledge and acceptance of three alternative reproductive options that could be used to decrease the risk of future children having SCD despite a relatively high number of parents reportedly altering their reproductive plans because of SCD. Parents endorsed the desire for others to gain information earlier to attain fully informed decisions, as for some, this would have altered their prior decisions. Ultimately, families should be able to make informed reproductive decisions and have access to reproductive options, if desired. Future directions include study of parental desires outside of our limited study population and informing opportunities for SCD education, dissemination of newborn screening results, and access to preconception counseling including individual/partner testing, genetic counseling, and alternative reproductive options. Disclosures No relevant conflicts of interest to declare.

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3239 Red blood cell (RBC) transfusion is a key treatment for patients with sickle cell disease (SCD), but remains complicated by the high incidence of RBC immunization. Despite provision of phenotypic Rh D, C, and E antigen-matched donor RBCs, patients continue to develop Rh antibodies. In many cases, these antibodies are considered autoantibodies with specificities for D, C, and e antigens because the patient's own RBCs type serologically positive for the corresponding antigen. Recent evidence is emerging that Rh alloimmunization within populations of African origin is complicated by the genetic diversity of this locus. Individuals of African ancestry often carry RH alleles that differ from those defined as conventional alleles that are common in Europeans and other ethnic groups. These “variant” alleles encode Rh proteins, often with multiple amino acid changes, that either lack common epitopes or produce novel immunogenic epitopes. The clinical significance of Rh alloimmunization in patients with SCD with variant RH genes is largely unknown. In the present study, we performed RH genotyping in 212 patients with SCD to determine prevalence of RH variants, the association with Rh alloimmunization, and the clinical significance measured by changes in hematologic parameters at time of antibody detection. RH genotyping was performed by polymerase chain reaction (PCR) amplification using RHD-specific and RHCE-specific primers designed in the flanking intronic regions and analyzed by direct sequencing of exons, and/or a combination of multiple PCR-restriction fragment length polymorphism (RFLP) assays and by RHD and RHCE BeadChip arrays. We identified variant RH alleles in 88.7% (188/212) of patients with SCD. Twelve different RHD and 13 RHCE alleles encoding variant Rh D, C, and e antigens were represented in this cohort of patients. In 172 patients with >1 RBC transfusion (median 125 units), 55 antibodies were identified with Rh specificity despite antigen-positive status (28 anti-D, 16 anti-e, 9 anti-C, and 2 anti-E). RH genotypes revealed 47.3% of these antibodies developed in patients who lacked the corresponding conventional RH allele, and would be considered Rh alloantibodies. In 43.6%, RH genotypes predicted expression of the conventional antigen to which the antibody was directed, suggesting these were potentially autoantibodies. However, these patients had at least one other RH allele that was altered. This may suggest that the presence of one variant protein potentially changes the Rh complex in the membrane, and carrying at least one conventional RH allele is not necessarily protective against production of Rh specific antibodies. In the remaining 9.1%, we detected no variant RHD or RHCE alleles, and complete gene sequencing is in progress to confirm the absence of novel mutations. Importantly, to determine clinical significance, we evaluated whether Rh antibodies in patients carrying variant alleles caused decreased transfused RBC survival by comparing the patient's hematologic parameters at the time of antibody detection with the baseline pre-transfusion parameters. In all but 4 cases, Rh antibodies in antigen-positive patients occurred in chronically transfused patients. Therefore, baseline values were determined from the average pre-transfusion hemoglobin, hematocrit and % hemoglobin S level for the 6–12 months preceding antibody detection. Compromised transfused RBC survival was determined by a lower hemoglobin/hematocrit or higher % hemoglobin S level at time of antibody formation compared to the patient's baseline. Forty percent of antibodies were associated with delayed hemolytic transfusion reactions or decreased transfused RBC survival. Our data suggest that the high prevalence of variant RH alleles in patients with SCD is associated with clinically significant immunization. Discrimination of allo- versus auto- antibodies in this chronically transfused patient population presents a significant technical challenge and suggests a role for RH genotyping in the clinical evaluation of Rh antibodies and to improve RBC matching. Importantly, in this study Rh antibodies in patients with variant RH often compromised transfused RBC survival and, therefore, were clinically significant and may be targets for prevention strategies analogous to standard phenotype matching for C, E, and K. Disclosures: No relevant conflicts of interest to declare.