Post-transfusion biotin-labeled red blood cell survival studies in pediatric sickle cell disease with antibodies of uncertain significance.

BACKGROUND: Red blood cell (RBC) antibodies are common in multiply transfused patients with sickle cell disease (SCD). Unlike RBC alloantibodies, the potential of autoantibodies to cause post-transfusion hemolysis may be uncertain. Biotin-labeling provides a direct measurement of red cell survival (RCS) over time, thus can be used to assess the clinical significance of RBC antibodies. Antibodies to biotinylated RBC (B-RBC) occasionally are detected after exposure, which may impact B-RBC survival in subsequent RCS studies. STUDY DESIGN AND METHODS: Pediatric patients with SCD receiving monthly chronic transfusions underwent RCS studies, receiving aliquots of allogeneic RBC labeled at distinct densities of biotin (2-18 µg/mL). B-RBC survival was followed for 4 months post-transfusion, and B-RBC antibody screening for 6 months. Patients with warm autoantibodies (WAA) or B-RBC antibodies are reported here. RESULTS: RBC antibodies were detected during RCS in four patients: one with WAA, one with WAA followed by B-RBC-specific antibodies, and two with transient B-RBC antibodies within the first 5 weeks of exposure. B-RBC half-lives (T50) ranged 37.6-61.7 days (mean 47.8 days). There was no evidence of increased hemolysis or accelerated B-RBC clearance in the presence of WAA or B-RBC antibodies. DISCUSSION: Biotinylation of allogenic RBC can be used to assess the possible effects of RBC antibodies on transfusion survival in individual cases, particularly when it is uncertain if the detected antibodies may result in hemolysis. In the cases presented here, neither WAA nor B-RBC antibodies were associated with significant shortening of B-RBC survival in individuals with SCD.

Survival of transfused red blood cells from a donor with alpha-thalassemia trait in a recipient with sickle cell disease.

BACKGROUND: Post-transfusion survival of donor red blood cells (RBCs) is important for effective chronic transfusion therapy in conditions including sickle cell disease (SCD). Biotin labeling RBCs allows direct in vivo measurement of multiple donor RBC units simultaneously post-transfusion. STUDY DESIGN AND METHODS: In an observational trial of patients with SCD receiving monthly chronic transfusion therapy, aliquots of RBCs from one transfusion episode were biotin-labeled and infused along with the unlabeled RBC units. Serial blood samples were obtained to measure RBC survival. Donor units were tested for RBC indices, hemoglobin fractionation, and glucose-6-phosphate dehydrogenase (G6PD) enzyme activity. For microcytic donor RBCs (MCV < 70 fL), HBA1 and HBA2 genetic testing was performed on whole blood. RESULTS: We present one recipient, a pediatric patient with SCD and splenectomy who received two RBC units with aliquots from each unit labeled at distinct biotin densities (2 and 18 µg/mL biotin). One donor unit was identified to have microcytosis (MCV 68.5 fL after biotinylation); whole blood sample obtained at a subsequent donation showed 2-gene deletion alpha-thalassemia trait (ɑ-3.7kb/ɑ-3.7kb) and normal serum ferritin. G6PD activity was >60% of normal mean for both. The RBCs with alpha-thalassemia RBC had accelerated clearance and increased surface phosphatidylserine post-transfusion, as compared with the normocytic RBC (half life 65 vs. 86 days, respectively). DISCUSSION: Post-transfusion RBC survival may be lower for units from donors with alpha-thalassemia trait, although the impact of thalassemia trait donors on transfusion efficacy requires further study.

Procedural adverse events in pediatric patients with sickle cell disease undergoing chronic automated red cell exchange.

BACKGROUND: Chronic automated red cell exchange (RCE) is increasingly employed for sickle cell disease (SCD). There is a paucity of data on the incidence of RCE adverse events (AEs) and potential patient and procedural risk factors for AEs. METHODS: A retrospective review of pediatric SCD patients receiving chronic RCE over 3 years was performed to determine the frequency of AEs and identify procedural and patient AE risk factors. AE incidence, AE rate, incidence rate ratios (IRRs), and relative risks (RRs) were calculated based on various procedural and patient characteristics by univariable (UV) and multivariable (MV) analyses. RESULTS: In 38 patients receiving 760 procedures, there were 150 (19.7%) AEs, 36 (4.7%) were symptomatic AEs. AE rates were 20.2 [95% CI 17.2, 23.6] and 4.8 [95% CI 3.49, 6.70] per 100 person months for AEs and symptomatic AEs, respectively. AE incidences were: hypocalcemia (117; 15.4%), dizziness (22; 3.0%), hypotension (15; 2.0%), and nausea (14; 1.8%). Patients with baseline Hct ≥30% experienced more total AEs and symptomatic AEs. Patients with pre-procedure systolic BP <50th percentile, severe CNS vasculopathy, and non-SCA genotype (HbSC or Sß+ thalassemia) exhibited more total AEs. IHD depletion was not associated with an increased incidence of AEs or symptomatic AEs. CONCLUSION: SCD patients with Hct ≥30%, systolic BP <50th percentile, severe CNS vasculopathy, and possibly non-SCA genotype may be at higher risk for RCE-related AEs. The effect of IHD on AE risk is likely minimal. Individualized AE risk assessment should be performed in all SCD patients undergoing chronic automated RCE.

Glucose-6-phosphate dehydrogenase deficiency is more prevalent in Duffy-null red blood cell transfusion in sickle cell disease.

BACKGROUND: Resistance to malaria infection may be conferred by erythrocyte genetic variations including glucose-6-phosphate dehydrogenase (G6PD) deficiency and lack of Duffy antigens. In red blood cell (RBC) transfusion, G6PD deficiency may shorten transfusion survival. Because Duffy-null units are commonly transfused in sickle cell disease (SCD) due to antigen matching protocols, we examined whether Duffy-null donor RBC units have a higher prevalence of G6PD deficiency. MATERIALS AND METHODS: Pediatric patients with SCD on chronic transfusion therapy were followed prospectively for multiple transfusions. RBC unit segments were collected to measure G6PD activity and RBC genotyping. The decline in donor hemoglobin (ΔHbA) following transfusion was assessed from immediate posttransfusion estimates and HbA measurements approximately 1 month later. RESULTS: Of 564 evaluable RBC units, 59 (10.5%) were G6PD deficient (23 severe, 36 moderate deficiency); 202 (37.6%) units were Duffy-null. G6PD deficiency occurred in 40 (19.8%) Duffy-null units versus 15 (4.5%) Duffy-positive units (p < .0001). In univariate analysis, the fraction of Duffy-null RBC units per transfusion was associated with greater decline in HbA (p = .038); however, in multivariate analysis, severe G6PD deficiency (p = .0238) but not Duffy-null RBC (p = .0139) were associated with ΔHbA. CONCLUSION: Selection of Duffy-null RBC units may result in shorter in vivo survival of transfused RBCs due to a higher likelihood of transfusing units from G6PD deficient donors.

The burden of respiratory syncytial virus infections among children with sickle cell disease.

BACKGROUND: Although respiratory syncytial virus (RSV) is the leading cause of pediatric lower respiratory tract infections, the burden of RSV in children with sickle cell disease (SCD) is unknown. METHODS: We conducted a retrospective, nested, case-control study of children with SCD <18 years who had respiratory viral panels (RVPs) performed at Children's Healthcare of Atlanta from 2012 to 2019. We abstracted the medical records to describe the demographics, clinical features, and outcomes of children who tested positive for RSV (cases) versus children who tested negative (controls). We calculated the annual incidence of RSV and related hospitalization rates with 95% confidence intervals (CIs) and used multivariate logistic regression to evaluate associations. RESULTS: We identified 3676 RVP tests performed on 2636 patients over seven respiratory seasons resulting in 219/3676 (6.0%) RSV-positive tests among 160/2636 (6.1%) patients. The average annual incidence of laboratory-confirmed RSV infection among children with SCD was 34.3 (95% CI 18.7-49.8) and 3.8 (95% CI 0.5-7.0) cases per 1000 person-years for those <5 years and 5-18 years, respectively. The RSV-related hospitalization rate for children <5 years was 20.7 (95% CI 8.5-32.8) per 1000 person-years. RSV-positive cases were significantly younger than RSV-negative patients (3.8 years vs 7.6 years, P < .001). Of RSV-positive cases, 22 (13.8%) developed acute chest syndrome and nine (5.6%) required intensive care, which was not significantly different from RSV-negative children with SCD. CONCLUSION: RSV infections are common in children with SCD with higher burden in younger patients. RSV is associated with considerable morbidity, including higher rates of hospitalization compared to the general population.

Microbiology and radiographic features of osteomyelitis in children and adolescents with sickle cell disease.

BACKGROUND: Children with sickle cell disease (SCD) are at increased risk for bacterial infections including osteomyelitis (OM). Fever and bone pain, key presenting symptoms of OM, are common in SCD, thus complicating diagnosis. We reviewed presentation, imaging features, and microbiologic etiologies of children with SCD treated for OM. METHODS: The comprehensive SCD clinical database of children and adolescents with SCD followed at a single, large tertiary pediatric center were searched to identify all diagnostic coding for potential cases of osteomyelitis in children ages 6 months to 21 years from 2010 to 2019. Medical charts were reviewed to determine OM diagnostic probability based on radiographic and microbiologic findings and the duration of prescribed antibiotic treatment for OM. RESULTS: Review of 3553 patients (18 039 person-years) identified 20 episodes of probable OM in 19 children. Magnetic resonance imaging (MRI) findings to support OM were definitive in 4/19 (21%), probable in 10/19 (53%), suspected in 5/19 (26%), based on blinded radiologist review. Blood and/or operative cultures from bone and tissue debridement isolated Salmonella species in seven (35%) cases and methicillin-susceptible Staphylococcus aureus (MSSA) in two (10%). Six patients received antibiotic treatment prior to obtainment of cultures. Of culture-positive cases, MRI findings for OM were definitive or probable in six of nine (67%), suspected in three of nine (33%). CONCLUSIONS: Distinction between OM and sickle-related bone infarct or vasoocclusion is difficult based on imaging findings alone. Early attainment of blood and operative cultures increases the likelihood of identifying and adequately treating OM.

Influenza vaccine effectiveness and disease burden in children and adolescents with sickle cell disease: 2012-2017.

BACKGROUND: Data are limited on the burden of influenza and seasonal influenza vaccine effectiveness (VE) in children with sickle cell disease (SCD). METHODS: We used a prospectively collected clinical registry of SCD patients 6 months to 21 years of age to determine the influenza cases per 100 patient-years, vaccination rates, and a test-negative case-control study design to estimate influenza VE against medically attended laboratory-confirmed influenza infection. Influenza-positive cases were randomly matched to test-negative controls on age and influenza season in 1:1 ratio. We used adjusted logistic regression models to compare odds ratio (OR) of vaccination in cases to controls. We calculated VE as [100% × (1 - adjusted OR)] and computed 95% confidence intervals (CIs) around the estimate. RESULTS: There were 1037 children with SCD who were tested for influenza, 307 children (29.6%) had at least one influenza infection (338 infections, incidence rate 3.7 per 100 person-years; 95% CI, 3.4-4.1) and 56.2% of those tested received annual influenza vaccine. Overall VE pooled over five seasons was 22.3% (95% CI, -7.3% to 43.7%). Adjusted VE estimates ranged from 39.7% (95% CI, -70.1% to 78.6%) in 2015/2016 to -5.9% (95% CI, -88.4% to 40.4%) in the 2016/17 seasons. Influenza VE varied by age and was highest in children 1-5 years of age (66.6%; 95% CI, 30.3-84.0). Adjusted VE against acute chest syndrome during influenza infection was 39.4% (95% CI, -113.0 to 82.8%). CONCLUSIONS: Influenza VE in patients with SCD varies by season and age. Multicenter prospective studies are needed to better establish and monitor influenza VE among children with SCD.

Patient and family experience with chronic transfusion therapy for sickle cell disease: A qualitative study.

BACKGROUND: There is a limited understanding of the patient and family experience of Chronic Transfusion Therapy (CTT) for prevention of complications of Sickle Cell Disease (SCD). We sought to understand patient and family experience with CTT using qualitative methods. METHODS: Fifteen parents of children < 18 years old and nine children 12-18 years old with SCD who were receiving CTT for > 1 year were interviewed using a semi-structured interview format, and interviews were analyzed using open coding methods. RESULTS: Four themes created a narrative of the patient and family experience of CTT: 1) Burden of CTT, 2) Coping with CTT, 3) Perceived benefits and risks of CTT, and 4) Decision making regarding CTT. Participants reported substantial burden of CTT, including the impact of CTT on daily life and family, distress about venous access, burden of chelation therapy, and anxiety about CTT complications. Participants described how they coped with CTT. Participants reported increased energy, decreased pain, fewer hospitalizations, and stroke prevention with CTT, but also recognized complications of CTT, though awareness was limited in adolescents. Parents described sharing in the informed decision-making process with their healthcare provider about CTT, but adolescent patient participants reported that they were not involved in this process. CONCLUSIONS: CTT is associated with significant patient and family burden. Support from family, healthcare providers and school may help individuals cope with some of this burden. These findings provide the basis for future studies to identify strategies to mitigate the burden of CTT and improve the patient experience with this therapy. Future studies should also systematically assess patient knowledge about the key components of CTT and chelation using quantitative assessments.

Health literacy and knowledge of chronic transfusion therapy in adolescents with sickle cell disease and caregivers.

BACKGROUND: Patients with sickle cell disease (SCD) may require chronic transfusion therapy (CTT) for prevention of stroke or other complications. Limited health literacy (HL) is common and is associated with poor health-related knowledge and outcomes in chronic disease. We sought to assess HL and transfusion knowledge in patients with SCD on CTT and their caregivers. METHODS: A cross-sectional study of patients was conducted in outpatient hematology clinics. Forty-five pairs of adolescent patients and caregivers and 20 caregivers of pre-adolescent patients completed the Newest Vital Sign HL assessment and answered questions assessing SCD and transfusion knowledge. Community-level median income and unemployment rates were estimated from Census data. We computed the correlation of HL with knowledge and compared each to Census variables, payor status, educational attainment, and stroke. RESULTS: HL was inadequate in 22 (34%) caregivers and 31 (69%) adolescents. Adequate caregiver HL was associated with higher educational attainment but not community-level socioeconomics or payor status. Mean knowledge score was lower in adolescents than in caregivers and correlated with age in adolescents (r = 0.42, P = .004). HL correlated with knowledge (r = 0.46, P < .0001). There were no significant correlations of HL or knowledge between adolescents and their caregivers. Neither HL nor knowledge was associated with prior stroke. The greatest knowledge was demonstrated for iron overload and SCD genotype, whereas knowledge gaps existed in alloimmunization, indication for CTT, and SCD curative therapy. CONCLUSIONS: Enhanced educational resources in transfusion therapy, alloimmunization, and curative therapy are needed for patients with SCD and caregivers of all HL levels.

Incidence of invasive Haemophilus influenzae infections in children with sickle cell disease.

BACKGROUND: Children with sickle cell disease (SCD) are at increased risk for invasive infection with encapsulated bacteria. Antibiotic prophylaxis and immunizations against Streptococcus pneumoniae and Haemophilus influenzae type b (Hib) have decreased the overall incidence of invasive infections and have shifted distribution of serotypes causing disease toward those not covered by immunizations. We sought to determine the current incidence of invasive H. influenzae infections in children with SCD and to describe the clinical features and management of these infections. METHODS: Microbiology reports of a large pediatric tertiary care center were reviewed to identify all isolates of H. influenzae detected in sterile body fluid cultures from January 1, 2010 to December 31, 2017. Results were compared with the center's comprehensive clinical database of all children with SCD to identify all cases of children ages 0 to18 years with SCD with invasive H. influenzae disease for the same time period. RESULTS: We captured 2444 patients with SCD, with 14,336 person-years. There were eight episodes of H. influenzae bacteremia in seven children with SCD (five type f, two non-typable, one type a). Most episodes (7 of 8) were in children < 5 years. The incidence rate of invasive H. influenzae in SCD was 0.58/1000 person-years for ages 0 to 18 years and 1.60/1000 person-years for children age < 5 years. There were no deaths from H. influenzae infection. CONCLUSIONS: In the era of universal antibiotic prophylaxis and immunization against Hib, invasive H. influenzae disease due to nonvaccine serotypes remains a risk for children with SCD, particularly those under five years of age.

Kidney biopsy findings in children with sickle cell disease: a Midwest Pediatric Nephrology Consortium study.

BACKGROUND: Renal damage is a progressive complication of sickle cell disease (SCD). Microalbuminuria is common in children with SCD, while a smaller number of children have more severe renal manifestations necessitating kidney biopsy. There is limited information on renal biopsy findings in children with SCD and subsequent management and outcome. METHODS: This is a multicenter retrospective analysis of renal biopsy findings and clinical outcomes in children and adolescents with SCD. We included children and adolescents (age ≤ 20 years) with SCD who had a kidney biopsy performed at a pediatric nephrology unit. The clinical indication for biopsy, biopsy findings, subsequent treatments, and outcomes were analyzed. RESULTS: Thirty-six SCD patients (ages 4-19 years) were identified from 14 centers with a median follow-up of 2.6 years (0.4-10.4 years). The indications for biopsy were proteinuria (92%) and elevated creatinine (30%). All biopsies had abnormal findings, including mesangial hypercellularity (75%), focal segmental glomerulosclerosis (30%), membranoproliferative glomerulonephritis (16%), and thrombotic microangiopathy (2%). There was increased use of hydroxyurea, angiotensin-converting-enzyme inhibitors, and angiotensin receptor blockers following renal biopsy. At last follow-up, 3 patients were deceased, 2 developed insulin-dependent diabetes mellitus, 6 initiated chronic hemodialysis, 1 received a bone marrow transplant, and 1 received a kidney transplant. CONCLUSIONS: Renal biopsies, while not commonly performed in children with SCD, were universally abnormal. Outcomes were poor in this cohort of patients despite a variety of post-biopsy interventions. Effective early intervention to prevent chronic kidney disease (CKD) is needed to reduce morbidity and mortality in children with SCD.

Losartan therapy decreases albuminuria with stable glomerular filtration and permselectivity in sickle cell anemia.

Sickle cell nephropathy begins with hyperfiltration and microalbuminuria and may progress to renal failure. The aim of this study was to determine the effects of losartan on glomerular function and albumin excretion in sickle cell anemia (SCA). Individuals with SCA on hydroxyurea with persistent albuminuria were enrolled in a 1-year study of losartan. Glomerular filtration rate (GFR) measured by iohexol clearance, albumin excretion rate (AER), and fractional clearance of dextran were assessed at baseline, short-term (1-2month), and long-term (≥12month) intervals. Twelve subjects (6 microalbuminuria, 6 macroalbuminuria) completed short-term studies; 8 completed long-term studies. Baseline GFR was 112ml/min/1.73m2 (71-147ml/min/1.73m2). AER decreased significantly at the short-term (median decrease -134 mcg/min, p=0.0063). GFR was not significantly-different at short-term or long-term intervals. Dextran clearance improved for diameters smaller than albumin (<36Å) but not larger sizes. Losartan therapy for ≥1year in sickle nephropathy results in lower albumin excretion with stable GFR. Filtration of neutral molecules ≥36Å was not changed by losartan, suggesting that the effect of losartan is a mechanism other than alteration of glomerular filtration size-selectivity.

Hemoglobin A clearance in children with sickle cell anemia on chronic transfusion therapy.

BACKGROUND: Chronic transfusion therapy for sickle cell anemia reduces disease complications by diluting sickle-erythrocytes with hemoglobin A (HbA)-containing erythrocytes and suppressing erythropoiesis. Minor antigen mismatches may result in alloimmunization, but it is unknown if antigen mismatches or recipient characteristics influence HbA clearance posttransfusion. STUDY DESIGN AND METHODS: Children with sickle cell anemia on chronic transfusion therapy were followed prospectively for 12 months. All patients received units serologically matched for C/c, E/e, and K; patients with prior red blood cell (RBC) antibodies had additional matching for Fya , Jkb , and any previous alloantibodies. Patients' RBC antigen genotypes, determined by multiplexed molecular assays (PreciseType Human Erythrocyte Antigen, and RHCE and RHD BeadChip, Immucor) were compared to genotypes of transfused RBC units to assess for antigen mismatches. Decline in hbA (ΔHbA) from posttransfusion to the next transfusion was calculated for each transfusion episode. RESULTS: Sixty patients received 789 transfusions, 740 with ΔHbA estimations, and 630 with donor Human Erythrocyte Antigen genotyping. In univariate mixed-model analysis, ΔHbA was higher in patients with past RBC antibodies or splenomegaly and lower in patients with splenectomy. RBC antigen mismatches were not associated with ΔHbA. In multivariate linear mixed-effects modeling, ΔHbA was associated with RBC antibodies (2.70 vs. 2.45 g/dL/28 d, p = 0.0028), splenomegaly (2.87 vs. 2.28 g/dL/28 d, p = 0.019), and negatively associated with splenectomy (2.46 vs. 2.70 g/dL/28 d, p = 0.011). CONCLUSIONS: HbA decline was increased among patients with sickle cell anemia with prior immunologic response to RBC antigens and decreased among those with prior splenectomy, demonstrating that recipient immunologic characteristics influenced the clearance of transfused RBCs.

Glucose-6-phosphate-dehydrogenase deficient red blood cell units are associated with decreased posttransfusion red blood cell survival in children with sickle cell disease.

Chronic transfusion therapy (CTT) for sickle cell disease (SCD) reduces disease morbidity by suppressing the amount of circulating hemoglobin S (HbS)-containing red blood cells (RBC). The effectiveness of CTT depends on the rate of RBC clearance. Glucose-6-phosphate dehydrogenase (G6PD) deficient donor RBC may exhibit increased hemolysis, but it is unknown if transfusion of these units results in less effective transfusion outcomes in SCD. Children with SCD on CTT were followed prospectively for multiple transfusions. G6PD activity of transfused units was measured prior to expiration date. HbA clearance (ΔHbA) was calculated as the difference of estimated posttransfusion HbA to the pretransfusion HbA of the subsequent transfusion episode. Sixty-two patients received 388 transfusions. Of 755 RBC units, 687 (91%) had normal G6PD (>60% activity), 38 (5%) had moderately low G6PD (10-60% activity), and 30 (4%) had severely low G6PD (<10% activity). Of 358 evaluable transfusions, 54 (15%) included ≥1 G6PD deficient units, and 22 (6%) had ≥1 severely deficient units. The proportion of the transfusion episode consisting of G6PD deficient units was associated with increased ΔHbA for all G6PD deficient units (P = .05) and for severely G6PD deficient units (P = .0070). In multivariate mixed effects modeling, ΔHbA was positively associated with severely G6PD deficient units (P = .0074) and RBC alloimmunization (P = .03) and negatively associated with recipient splenectomy (P = .015). Higher ΔHbA was associated with higher HbS and reticulocyte counts at the subsequent transfusion episode. In conclusion, G6PD deficient RBC transfusions may have shorter in vivo survival and adversely affect the suppression of sickle erythropoiesis.

Red blood cell minor antigen mismatches during chronic transfusion therapy for sickle cell anemia.

BACKGROUND: Red blood cell (RBC) alloimmunization occurs at a high frequency in sickle cell anemia (SCA) despite serologic matching for Rh (C/c, E/e) and K antigens. RBC minor antigen genotyping allows for prediction of antigens and RH variants that may lead to alloimmunization. STUDY DESIGN AND METHODS: RBC antigen genotyping was performed on chronically transfused pediatric SCA patients, using PreciseType human erythrocyte antigen (HEA), RHCE, and RHD BeadChip arrays. All patients received C/c, E/e, and K serologically matched units (Category 1); patients with prior RBC antibodies were also matched for Fya , Jkb , and any antibodies (Category 2). The RBC genotypes of all leukoreduced (LR) units transfused over a 12-month period were determined by the prototype HEA-LR BeadChip assay. RESULTS: There were 2320 RBC units transfused to 90 patients in 1135 transfusion episodes. Thirty-five (38.9%) patients had homozygous or compound heterozygous RH variants. Seven new alloantibodies were detected, with alloantibody incidence of 0.706 in 100 units for Category 2 transfusions and 0.068 in 100 units for Category 1 (p = 0.02). Three patients on Category 2 transfusions formed new anti-Jsa and had a higher rate of exposure to Jsa than those who did not form anti-Jsa (20.4 vs. 8.33 exposures/100 units, p = 0.02). The most frequent mismatches were S (43.9%), Doa (43.9%), Fya (29.2%), M (28.4%), and Jkb (28.1%). CONCLUSIONS: Alloimmunization incidence was higher in those with prior RBC antibodies, suggesting that past immunologic responders are at higher risk for future alloimmunization and therefore may benefit from more extensive antigen matching beyond C/c, E/e, K, Fya , and Jkb .

Changes in urine albumin to creatinine ratio with the initiation of hydroxyurea therapy among children and adolescents with sickle cell disease.

BACKGROUND: Renal damage is a progressive complication of sickle cell disease (SCD) that begins in childhood and may progress to renal failure and early mortality in 12% of adults with hemoglobin SS (HbSS) SCD. Early sickle nephropathy is characterized by hyperfiltration and microalbuminuria; therefore, urine albumin to creatinine ratio (ACR) is an effective screening tool for its detection. PROCEDURE: This study investigated the effect of hydroxyurea (HU) therapy on urine ACR levels among children with SCD. A retrospective review was conducted to identify all patients with HbSS or HbSß0 thalassemia of age 7-18 years who began HU therapy in 2011-2013; a control group of patients not on HU were matched by age and baseline hemoglobin. All urine ACR measurements ≤24 months prior to and ≥24 months after HU initiation were recorded. RESULTS: There were 63 eligible patients on HU and 13 (25%) with albuminuria prior to HU initiation. Among those with baseline albuminuria, the median ACR was 96 mg/g prior to HU, 39 mg/g at 1 year (P = 0.02), and 25 mg/g at 2 years (P = 0.03). Albuminuria normalized in 37.5% (6/16) after 1 year and 61% (8/13) after 2 years of HU therapy. Among those without albuminuria prior to HU, 13% (6/47) developed albuminuria during HU therapy. Sixteen percent (13/80) of control patients had albuminuria in the beginning of study period, which normalized in 15% (two of 13) of patients at 1-year follow up. CONCLUSION: Introduction of HU is associated with significant decreases in urine ACR in children with SCD and albuminuria.

Class I and II HLA antibodies in pediatric patients with thalassemia major.

BACKGROUND: HLA alloimmunization is a potential complication of red blood cell (RBC) transfusion with detrimental consequences for future organ or hematopoietic stem cell transplantation. STUDY DESIGN AND METHODS: The study aimed to determine the prevalence and specificity of HLA antibodies among pediatric patients with thalassemia major (TM) and antibody changes over time while on leukoreduced chronic transfusion therapy. HLA antibodies were measured at two or more time points in children and young adults ages 3 to 21 years with TM. HLA Class I and II antibodies were measured by FlowPRA screening. Positive screening assays were confirmed with LabScreen single-antigen bead assays for antibody specificity. RESULTS: HLA antibodies were detected in 10 of 19 (53%) subjects: seven of 19 (37%) with HLA Class I and II antibodies, two of 19 (11%) with only HLA Class I antibodies, and one of 19 (5%) with only HLA Class II antibodies. Subjects with HLA antibodies were older (14.6 years vs. 7.1 years, p = 0.05), predominantly male (80%), and more likely to have a remote history of nonleukoreduced transfusions (p = 0.057). Median time between testing was 3.7 years. De novo HLA antibodies were detected in two of 11 patients who initially had negative panel-reactive antibody screens, while one subject lost detection of Class II antibody. Two of seven patients with HLA antibodies had antibodies to self-HLA. CONCLUSION: HLA antibodies have a high prevalence in TM patients and may be associated with nonleukoreduced transfusions and older age. For such patients, antibody identification will be useful if subsequent organ or stem cell transplantation is needed.

Recipient-derived EBV-positive Monomorphic Plasmacytoma Type Posttransplant Lymphoproliferative Disorder After Allogeneic Stem Cell Transplant for Severe Aplastic Anemia: A Case Report.

Monomorphic plasmacytoma-type posttransplant lymphoproliferative disorder (PTLD) has not been reported after pediatric hematopoietic stem cell transplantation. We present a child with hepatitis-associated severe aplastic anemia who underwent an unrelated allogeneic hematopoietic stem cell transplantation and subsequently developed graft failure and an Epstein-Barr virus-positive monomorphic plasmacytoma-type PTLD of recipient origin. Despite broad-spectrum antimicrobials, weaning immunosuppression, rituximab administration, and a stem cell boost she died from complications of PTLD and a fungal pulmonary infection on day +78.

Hemoglobin F Only Syndrome at Birth: A Case of Maternal HbA2' Complicating the Diagnosis of ß-Thalassemia.

An asymptomatic infant of Ghanaian descent had hemoglobin F only detected on newborn screening. ß-globin gene sequencing identified the intervening sequence (IVS)-II-849 (A → G) mutation with no normal ß-globin gene. ß-globin/δ-globin gene sequencing showed that both parents were heterozygous for the IVS-II-849 (A → G) mutation. The mother was heterozygous for the HbA2' δ-globin mutation (δ16 (A13) Gly → Arg), thus ß-thalassemia trait was unrecognized due to coinheritance of HbA2'. The infant developed anemia, splenomegaly, and began transfusion therapy by the age 6 of months. This is the first report of ß-thalassemia major with homozygous IVS-II-849 (A → G) mutations. This case highlights the importance of δ-globin gene mutations in prenatal testing.