Genetic Analysis of Patients With Sickle Cell Anemia and Stroke Before 4 Years of Age Suggest an Important Role for Apoliprotein E

Background: Ischemic stroke is a devastating complication affecting children with sickle cell anemia. Genetic factors are likely to be important in determining the risk of stroke but are poorly defined. Methods: We have studied a cohort of 19 children who had an overt ischemic stroke before 4 years of age. We predicted genetic determinants of stroke would be more prominent in this group. We performed whole exome sequencing on this cohort and applied 2 hypotheses to our variant filtering. First, we looked for strong, potentially mono- or oligogenic variants for ischemic stroke, and second, we considered that more common polygenic variants will be enriched in our cohort. Candidate variants emerging from both strategies were validated in a cohort of 283 patients with sickle cell anemia and known pediatric cerebrovascular outcomes. We used principal component analysis in this cohort to control for relatedness and population substructure. Results: Our primary finding was that the Apoliprotein E genotypes ε2/ε4 and ε4/ ε4, defined by the interplay of rs7412 and rs429358 , were associated with increased stroke risk, with an odds ratio of 4.35 ([95% CI, 1.85–10.0] P =0.0011) for ischemic stroke in the validation cohort. We also found that rs2297518 in NOS (NO synthase) 2 (odds ratio, 2.25 [95% CI, 1.21–4.19]; P =0.014) and rs2230123 in signal transducer and activator of transcription (odds ratio, 2.60 [95% CI, 1.30–5.20]; P =0.009) both had increased odds ratios for ischemic stroke, although these two variants were below the threshold for statistical significance after correction for multiple testing. Conclusions: These data identify new loci for future functional investigations into cerebrovascular disease in sickle cell anemia. Based on African population reference allele frequencies, the Apoliprotein E genotypes would be present in about 10% of children with sickle cell anemia and represent a genetic risk factor that is potentially modifiable by both dietary and pharmaceutical manipulation of its dyslipidemic effects.

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Ischemic Stroke in Children and Young Adults with Sickle Cell Disease (SCD) in the Post-STOP Era

Blood ◽

10.1182/blood.v126.23.68.68 ◽

2015 ◽

Vol 126 (23) ◽

pp. 68-68 ◽

Cited By ~ 3

Author(s):

Janet L. Kwiatkowski ◽

Julie Kanter ◽

Heather J. Fullerton ◽

Jenifer Voeks ◽

Ellen Debenham ◽

...

Keyword(s):

Ischemic Stroke ◽

High Risk ◽

Sickle Cell Disease ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Stroke Prevention ◽

Cell Disease ◽

Clinical Series ◽

The Mean

Abstract Background: The Stroke Prevention Trial in Sickle Cell Anemia (STOP) and Optimizing Primary Stroke Prevention in Sickle Cell Anemia (STOP 2) established routine transcranial Doppler ultrasound (TCD) screening with indefinite chronic red cell transfusions (CRCT) for children with abnormal TCD as standard of care. To identify children at high-risk of stroke, annual TCD screening is recommended from ages 2 to 16 years, with more frequent monitoring if the result is not normal. A reduction in stroke incidence in children with SCD has been reported in several clinical series and analyses utilizing large hospital databases when comparing rates before and after the publication of the STOP study in 1998. We sought to determine the rate of first ischemic stroke in a multicenter cohort of children who had previously participated in the STOP and/or STOP 2 trials and to determine whether these strokes were screening or treatment failures. Subjects and Methods: Between 1995 and 2005, STOP and STOP 2 (STOP/2) were conducted at 26 sites in the US and Canada. These studies included 3,835 children, ages 2 to 16 y with SCD type SS or S-beta-0-thalassemia. Participation in STOP/2 ranged from a single screening TCD to randomization. STOP 2 also had an observational arm for children on CRCT for abnormal TCD whose TCD had not reverted to normal. The Post-STOP study was designed to follow-up the outcomes of children who participated in one or both trials. 19 of the 26 original study sites participated in Post-STOP, contributing a total of 3,539 (92%) of the STOP/2 subjects. After exit from STOP/2, these children received TCD screening and treatment according to local practices. Data abstractors visited each clinical site and obtained retrospective data from STOP/2 study exit to 2012-2014 (depending on site) including follow-up TCD and brain imaging results, clinical information, and laboratory results. Two vascular neurologists, blinded to STOP/2 status and prior TCD and neuroimaging results, reviewed source records to confirm all ischemic strokes, defined as a symptomatic cerebral infarction; discordant opinions were resolved through discussion. For the first Post-STOP ischemic stroke, prior TCD result and treatment history subsequently were analyzed. Results: Of the 3,539 subjects, follow-up data were available for 2,850 (81%). Twelve children who had a stroke during STOP or STOP2 were excluded from these analyses resulting in data on 2,838 subjects. The mean age at the start of Post-STOP was 10.5 y and mean duration of follow-up after exiting STOP/2 was 9.1 y. A total of 69 first ischemic strokes occurred in the Post-STOP observation period (incidence 0.27 per 100 pt years). The mean age at time of stroke was 14.4±6.2 (median 13.8, range 3.5-28.9) y. Twenty-five of the 69 patients (36%) had documented abnormal TCD (STOP/2 or Post-STOP) prior to the stroke; 15 (60%) were receiving CRCT and 9 (36%) were not (treatment data not available for 1 subject). Among the 44 subjects without documented abnormal TCD, 29 (66%) had not had TCD re-screen in the Post-STOP period prior to the event; 7 of these 29 (24%) were 16 y or older at the start of Post-STOP, which is beyond the recommended screening age. Four of the 44 (9%) patients had inadequate TCD in Post-STOP (1 to 10.7 y prior to event). Six (14%) had normal TCD more than a year before the event (1.2 - 4 y); all but one of these children were younger than 16 y at the time of that TCD. Only 5 (11%) had a documented normal TCD less than 1 year prior to the event. Conclusions: In the Post-STOP era, the rate of first ischemic stroke was substantially lower than that reported in the Cooperative Study of Sickle Cell Disease, prior to implementation of TCD screening. Many (39%) of the Post-STOP ischemic strokes were associated with a failure to re-screen according to current guidelines, while only 11% occurred in children who had had recent low-risk TCD. Among those known to be at high risk prior to stroke, treatment refusal or inadequate treatment may have contributed. While TCD screening and treatment are effective at reducing ischemic stroke in clinical practice, significant gaps in screening and treatment, even at sites experienced in the STOP protocol, remain to be addressed. Closing these gaps should provide yet further reduction of ischemic stroke in SCD. Disclosures No relevant conflicts of interest to declare.

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Sickle Cell Trait and Risk of Ischemic Stroke in Young Adults

Stroke ◽

10.1161/strokeaha.119.028404 ◽

2020 ◽

Vol 51 (9) ◽

Author(s):

Rebecca V. Zhang ◽

Kathleen A. Ryan ◽

Haley Lopez ◽

Marcella A. Wozniak ◽

Michael S. Phipps ◽

...

Keyword(s):

Young Adults ◽

Ischemic Stroke ◽

Sickle Cell ◽

Early Onset ◽

Odds Ratio ◽

Sickle Cell Trait ◽

Smoking Status ◽

Population Based ◽

Logistic Regression Models ◽

Increased Risk

Background and Purpose: Approximately 8% of Blacks have sickle cell trait (SCT), and there are conflicting reports from recent cohort studies on the association of SCT with ischemic stroke (IS). Most prior studies focused on older populations, with few data available in young adults. Methods: A population-based case-control study of early-onset IS was conducted in the Baltimore-Washington region between 1992 and 2007. From this study, 342 Black IS cases, ages 15 to 49, and 333 controls without IS were used to examine the association between SCT and IS. Each participant’s SCT status was established by genotyping and imputation. For analysis, χ 2 tests and logistic regression models were performed with adjustment for potential confounding variables. Results: Participants with SCT (n=55) did not differ from those without SCT (n=620) in prevalence of hypertension, previous myocardial infarction, diabetes mellitus, and current smoking status. Stroke cases had increased prevalence in these risk factors compared with controls. We did not find an association between SCT and early-onset IS in our overall population (odds ratio=0.9 [95% CI, 0.5–1.7]) or stratified by sex in males (odds ratio=1.26 [95% CI, 0.56–2.80]) and females (odds ratio=0.67 [95% CI, 0.28–1.69]). Conclusions: Our data did not find evidence of increased risk of early-onset stroke with SCT.

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Risk Factors for Intracranial Hemorrhage in Children with Sickle Cell Anemia.

Blood ◽

10.1182/blood.v104.11.1657.1657 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1657-1657

Author(s):

John J. Strouse ◽

Michael R. DeBaun ◽

James F. Casella

Keyword(s):

Risk Factors ◽

Blood Pressure ◽

Ischemic Stroke ◽

Steady State ◽

Sickle Cell ◽

Intracranial Hemorrhage ◽

Sickle Cell Anemia ◽

Small Sample ◽

Acute Chest Syndrome ◽

Corticosteroid Administration

Background: Intracranial hemorrhage (ICH) is an uncommon, but devastating, complication of sickle cell disease (SCD) with mortality from 30 to 65%. Most reported cases are in adults; little is known about children. Proposed risk factors include previous ischemic stroke, aneurysms, low steady-state hemoglobin, high steady-state leukocyte count, acute chest syndrome, and hypertransfusion. Methods: Retrospective case-control study designed to characterize and evaluate risk factors for ICH among children with SCD age < 19 years hospitalized at Johns Hopkins Children’s Center from January 1979 to March 2004. Cases had SCD and ICH (intraparenchymal (IPH), subarachnoid (SAH), or intraventricular (IVH) hemorrhage confirmed by neuroimaging or analysis of cerebrospinal fluid; traumatic subdural and epidural hemorrhages were excluded). Controls had SCD and ischemic stroke (focal neurological deficits with corresponding cerebral infarcts by neuroimaging). Both were identified by searching the hospital discharge database using ICD-9 codes for acute stroke and SCD and reviewing the Division of Pediatric Hematology’s records. ACS was defined as a new pulmonary infiltrate and two of the following: chest or rib pain, dyspnea, fever, tachypnea, grunting, nasal flaring, or retractions. Blood pressure was adjusted for age, sex, and hemoglobin genotype. Results: We identified 7 cases (mean age=11.2 years, range 2 to 16 years) and 9 controls (mean age 6.2 years, range 2 to 8 years). As expected, cases were significantly older than controls (p<0.01). All cases and controls had sickle cell anemia. Cases presented with impaired mental status (5/7), bradycardia (5/7), headache (4/7), and emesis (3/7). They often had multiple sites of hemorrhage (5/7) and died during the initial hospitalization (4/7). Five had IPH involving the frontal, parietal, and/or temporal lobes (2 of the patients with IPH also had SAH, 1 had IVH and 1 had both SAH and IVH). Two additional patients had SAH (one also with IVH). Most cases and controls had elevated systolic blood pressure at the time of stroke (4/7 cases, 8/9 controls). Cases had lower steady-state hemoglobin (mean±SE 7.1±0.3 g/dl vs. 7.7±0.4 g/dl), lower steady-state blood pressures (systolic 104±9 vs. 117±5 mm Hg, diastolic 50±5 vs. 61±5 mm Hg) and higher steady-state leukocyte counts (16,590±2823/ul vs. 13,851±2184/ul) than controls, but these differences were not statistically significant. Mean hemoglobin concentration was increased 2.8 g/dl (39.9%) from steady-state at the time of stroke in cases and was unchanged in controls (p=0.08). Other events in the two weeks before ICH associated with increased odds of ICH included transfusion (simple in 5 cases, erythrocytapheresis in 1), ACS (3 cases), and corticosteroid administration (high-dose dexamethasone for ACS in 2, stress doses for possible adrenal insufficiency in 1). Conclusions: In this group of children with SCD, ICH was associated with antecedent events including transfusion and possibly corticosteroids. Mortality was similar to that of adults with SCD and ICH. Limitations of this study include the small sample size and the retrospective design. The contribution of antecedent events to ICH in children with SCD deserves further evaluation. Odds Ratios of Intracranial Hemorrhage For Events in the Last 14 Days Event Odds Ratio (95% CI) P-value Transfusion 48 (1.8-2469) <0.01 ACS 6 (0.3-33) 0.26 Corticosteroids ∞ (1.3- ∞) 0.06

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Epidemiology and Risk Factors for Pain In Children and Adolescent with Sickle Cell Anemia.

Blood ◽

10.1182/blood.v116.21.1651.1651 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1651-1651 ◽

Cited By ~ 1

Author(s):

Deepika Darbari ◽

Onyinye Onyekwere ◽

Mehdi Nouraie ◽

Gregory J. Kato ◽

Caterina Minniti ◽

...

Keyword(s):

Risk Factors ◽

Confidence Interval ◽

Children And Adolescents ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Odds Ratio ◽

Severe Pain ◽

History Of ◽

Pain Crisis ◽

Thalassemia Trait

Abstract Abstract 1651 Background: Pain crises are the most common symptom experienced by individuals with sickle cell anemia (SCA). Frequency of pain crises varies significantly and high rate is a risk factor for higher mortality in adults with SCA. The risk factors for pain crises in children and adolescents with SCA are not completely understood. To determine factors associated with frequent severe pain crises, we analyzed the cohort of children and adolescents with SCA who were enrolled in the prospective study “The Pulmonary Hypertension and the Hypoxic Response in SCD (PUSH)”. All children were evaluated in their steady, non-crisis state. Methods: Family-reported history of number of severe pain crises in the preceding 12 months was recorded prospectively in 365 children and adolescents with SCA. Severe pain crises were defined as painful vaso-occlusive episodes requiring evaluation in Emergency Department (ED) or in-patient hospitalization. Lifetime history of red cell transfusions, echocardiography, and laboratory studies were obtained. Clinical and laboratory characteristics of study subjects who had ≥3 severe pain crises in the preceding year were compared to subjects with < 3 severe pain crises. Results: Study subject ranged in age from 3–20 years and 175 (48%) were female. Seventy two children (20 %) had ≥3 severe pain crises in the preceding year (frequent pain crisis group); 293 (80%) children had < 3 severe pain crises (infrequent pain crisis group), including 224 (61%) subjects who had no admissions/ ED visits for pain. Associated factors for frequent pain crisis included older age (odds ratio 1.2; 95% confidence interval 1.12–1.35; P <0.001) and α-thalassemia trait (odds ratio 3.22; 95% confidence interval 1.55–6.69; P =0.002) while higher steady state serum lactate dehydrogenase (LDH) was associated with infrequent pain crisis (odds ratio 0.35; 95% confidence interval 0.13–0.98; P =0.045). In a group of patients without α-thalassemia trait, older age and low LDH were linked to frequent pain crisis. Subjects in the frequent pain crisis group had higher median hemoglobin (9.0 vs. 8.5 gm/dL; p=0.003) and higher ferritin (median 455 vs. 191 ng/mL; p=0.008). Higher ferritin in the frequent pain crisis group was mirrored by the higher percentage who reported >10 lifetime transfusions (42% vs. 22%; p=0.001). Median tricuspid regurgitation jet velocity (TRV) was higher in the frequent pain crisis group (2.41 vs. 2.31; p= 0.001) but the proportion of children with TRV>2.5 was not different (19.4% vs.11.5% in infrequent crises group; p=0.09). Hydroxyurea use was not different between the groups (51% vs. 40%; p=0.08) nor was fetal hemoglobin (10% vs. 12%; p=0.2). Conclusions: The occurrence of severe pain crisis varies among children and adolescents with SCA with a large number of children experiencing no severe painful episodes. Consistent with the Cooperative Study of Sickle Cell Disease report, the risk of severe pain crisis increases with age. Individuals with α-thalassemia trait are likely to experience more frequent pain crises possibly related to higher hemoglobin concentration and viscosity. However, even after controlling for α-thalassemia trait, children and adolescents who reported more frequent severe pain crises showed evidence of less hemolysis, consistent with a hypothetical model associating the hemolytic subphenotype of SCA with less frequent vasoocclusive pain crises. Further studies are indicated to identify the molecular mechanisms of pain in sickle cell anemia. Disclosures: No relevant conflicts of interest to declare.

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Genetic Determinants of Hemolysis in Sickle Cell Anemia.

Blood ◽

10.1182/blood.v120.21.2104.2104 ◽

2012 ◽

Vol 120 (21) ◽

pp. 2104-2104

Author(s):

Jacqueline N Milton ◽

Helen Rooks ◽

Emma Drasar ◽

Elizabeth L McCabe ◽

Clinton T. Baldwin ◽

...

Keyword(s):

Sickle Cell ◽

Sickle Cell Anemia ◽

Globin Gene ◽

Principal Component ◽

Regulatory Elements ◽

Intravascular Hemolysis ◽

Plasma Hemoglobin ◽

Hypersensitive Sites ◽

Gene Regulatory Elements ◽

Gene Regulatory

Abstract Abstract 2104 The phenotype of sickle cell disease is caused by sickle vasoocclusion and hemolytic anemia. Hemolysis in sickle cell anemia has been associated with complications that were presumed to result in part from vascular nitric oxide depletion due to scavenging by free plasma hemoglobin. Though plasma hemoglobin is a specific marker of intravascular hemolysis and red cell survival studies are the most definitive method of establishing the extent of hemolysis, these tests are rarely done and not available in large cohorts. However, the intensity of hemolysis can be estimated by the reticulocyte count, lactate dehydrogenase (LDH), aspartate aminotransaminase (AST) and bilirubin levels, all of which are commonly measured in cohort studies, although none of which is specific for hemolysis. We previously reported the results of a genome-wide association study (GWAS) of hemolysis where we used as a phenotype a new measure of the rate of intravascular hemolysis appropriate for cohort studies and GWAS. Using a principal component analysis of the commonly measured markers of hemolysis we derived a hemolytic score and found that the top SNPs associated with this score included a variant located in the first intron of NPRL3 (rs7203560; chr16p13.3, p=6.04×10−07) This result was replicated in two additional cohorts of 549 and 296 patients. We also established that while rs7203560 was associated with the ∝3.7 thalassemia gene deletion, when adjusted for HbF and ∝ thalassemia the association of NPRL3 with the hemolytic score remained significant (p=0.00375) and this association was also significant when examining only cases without ∝ thalassemia (p=0.02463). To further validate these results we studied 213 additional adult sickle cell anemia patients from King's College Hospital, London, UK. The mean age of these patients was 33 years. None had been treated with hydroxyurea and lab parameters obtained 3 months after, if transfused. Patients had similar clinical characteristics. The hemolytic score was calculated by using principal component analysis of the same markers of hemolysis. The SNPs associated with the hemolytic score in the primary study were genotyped in this cohort using TaqMan SNP genotyping assays according to standard Applied Biosystems protocol and their association with the derived hemolytic score studies using the same additive genetic model. The SNP rs7203560 replicated the association with hemolytic score (p= 0.03674) in this cohort. To examine the linkage disequilibrium (LD) structure of the region, we looked for conserved sequences in the α- globin cluster in multiple divergent species using the Basic Local Alignment Sequencing Tool (BLAST) to identify the approximate locations of the hypersensitive sites that are the major α-globin gene regulatory elements. On examination of the LD structure of SNPs in these regions with rs7203560, we found that rs7203560 was in LD with several SNPs located in and near the hypersensitive sites including rs2238368 (D'=1), rs2541612 (D'=0.89) and rs3331107 (D'=0.61). We hypothesize that rs7203560 is a marker for one or more variants in the major α-globin gene regulatory elements that down-regulate α-globin gene expression and cause a mild α thalassemia-like effect. In sickle cell anemia, perhaps by independently down-regulating expression of the α-globin genes, variants of the major ∝-globin gene regulatory loci reduce HbS concentration, lessen the polymerization potential of deoxy sickle hemoglobin and therefore retard hemolysis. Disclosures: No relevant conflicts of interest to declare.

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Hematopoietic Stem Cell Transplantation in Nigerian Children with Sickle Cell Anemia

Blood ◽

10.1182/blood.v126.23.4598.4598 ◽

2015 ◽

Vol 126 (23) ◽

pp. 4598-4598

Author(s):

Antonella Isgro ◽

Javid Gaziev ◽

Pietro Sodani ◽

Marco Andreani ◽

Manuela Testi ◽

...

Keyword(s):

Stem Cell ◽

Ischemic Stroke ◽

Hematopoietic Stem Cell Transplantation ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Conditioning Regimen ◽

Myeloablative Conditioning ◽

Hematopoietic Stem ◽

Free Survival ◽

Nigerian Children

Abstract Introduction: Sickle cell anemia (SCA) remains associated with high risks of morbidity and early death. Children with SCA are at high risk for ischemic stroke and transient ischemic attacks, secondary to intracranial arteriopathy involving carotid and cerebral arteries. Children with Black African variant SCA are prone to invasive infections caused by S. pneumonia, H. influenzae and Plasmodium falciparum (in malarias areas). In Africa, malaria contributes substantially to the early mortality of patients with SCA. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment for SCA. We report our experience with transplantation in a group of Nigerian children affected by SCA. Patients and Methods: This study included 36 consecutive SCA patients who underwent bone marrow transplantation from human leukocyte antigen (HLA)-identical sibling donors between 2010 and 2015 following a myeloablative-conditioning regimen. Patients received fludarabine (30 mg/m2/day) for 5 days and a conditioning regimen including targeted intravenous busulfan (14 mg/kg total dose) and cyclophosphamide (200 mg/kg total dose). Blood samples were collected in different Nigerian Hospitals and shipped to the Laboratory of the IME Foundation in Italy where were processed for DNA preparation on a fully automated system (Maxwell, Promega, Madison, WI). Low resolution HLA-A, -B, -C, -DRB1 and -DQB1 typing was performed using the polymerase chain reaction-sequence specific oligonucleotide (PCR-SSO) technique (LABType - One Lambda, Canoga Park, CA). Results: The median patient age was 10 years (range 2-17 years). Before transplantation, seventeen patients had recurrent, painful, vaso-occlusive crisis; twelve patients had recurrent painful crisis in association with acute chest syndrome; three patients experienced ischemic stroke and recurrent vaso-occlusive crisis; two patients experienced ischemic stroke; one patient exhibited leucocytosis; and one patient exhibited priapism. Of the 36 patients, 33 survived without sickle cell disease, with Lansky/Karnofsky scores of 100, following a myeloablative-conditioning regimen. The probabilities of survival, SCA-free survival, and transplant-related mortality after transplant were 92%, 92%, and 8%, respectively. All surviving patients remained free of any SCA-related events after transplantation. Within the frame of the HSCT program for the treatment of SCA, a total of 124 Nigerian families with 2 to 11 children (average 2.5) were typed for five HLA loci (A, B, C, DRB1 and DQB1) and the phased genotypes were unambiguously determined. Thirty-six percent of the patients had at his disposal within the family a HLA compatible sibling. Conclusion: The protocols used for the preparation to the transplant in thalassemia are very effective also in the other severe hemoglobinopathy as in the sickle cell anemia with more than 90% disease free survival. If a SCA patient has a HLA identical family member, the allogeneic cellular gene therapy through the transplantation of the hematopoietic stem cells should be performed as soon as possible, before the disease progresses through a treatment-related irreversible organ damage. Disclosures No relevant conflicts of interest to declare.

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Acute Chest Syndrome Is Strongly Associated Parvo Virus B19 Seroconversion in Patients with Hemoglobin SC Disease.

Blood ◽

10.1182/blood.v104.11.1664.1664 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1664-1664

Author(s):

Thomas D. Coates ◽

Carlton Dampier ◽

Karen Kalinyak ◽

Alice Lail ◽

William Mentzer ◽

...

Keyword(s):

Sickle Cell ◽

Odds Ratio ◽

Causal Relation ◽

Parvovirus B19 ◽

Statistical Significance ◽

Geographic Area ◽

Acute Chest Syndrome ◽

Aplastic Crisis ◽

Increased Risk ◽

Hemoglobin Sc Disease

Abstract Parvovirus B19 replicates principally in human erythrocyte precursors resulting in temporary cessation of erythropoiesis. In patients with sickle hemoglobinopathies, parvovirus B19 infection has been associated with acute chest syndrome and may lead to transient aplastic crisis. Evidence of prior infection with parvovirus B19 is found in 50 to 60% of adults. Infection appears to be followed by lifelong immunity. The objectives of the Study of Seroprevalence and Incidence of Parvovirus B19Infection in Children with Sickle Hemoglobinopathies are to determine the prevalence of parvovirus B19 antibodies in children less than 16 years old; determine the rate of parvovirus B19 seroconversion; and determine whether parvovirus B19 seroconversion is associated with the occurrence of aplastic crisis or acute chest syndrome. Between April 2000 and June 2002 a total of 1039 children from eight Comprehensive Sickle Cell Centers (CSCC) were enrolled in the study and 898 had at least one follow up visit. Participants ranged in age from <1 month to 16 years at enrollment (mean age 7.2, + 4.5 years), 47% were female, 53% were male. 67% had homozygous Hb SS disease, 24% had Hb SC disease, 6% had Hb SB+ disease, 3% had Hb SB0 disease, and <1% had other S sickle cell disease. The seroprevalence of parvovirus B19 in the cohort was 35%. Prevalence varied significantly by age, ranging from a low of 8% for children 1–2 years of age to 69% for children 13+ years of age (p<0.0001). The greatest increase in seroprevalence occurred between 6 and 7 years of age. Adjusted for age, there were no significant differences in seroprevalence by gender, clinical center, geographic area of residence (northeast, southeast, midwest, and west) sickle hemoglobinopathy, number of siblings, hemoglobin level, reticulocyte %, or among recipients of treatment with transfusion or hydroxyurea. Parvovirus B19 seroconversion was strongly associated with an increased risk of aplastic crisis in both SS (odds ratio of 29, 95% CI (11.3, 74.4)) and SC patients (odds ratio of 110, 95% CI (9.6, 1270.4)), even when controlling for age. Seroconversion was associated with an increased risk of acute chest syndrome in SC patients, (odds ratio of 6.4, 95% CI (1.9, 21.9)) but did not reach statistical significance in SS patients. These data show a clear causal relation between parvovirus B19 seroconversions and acute chest syndrome in subjects with hemoglobin SC disease and confirm the previously known association aplastic crisis.

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A GCH1 Haplotype Associated with Susceptibility to Vasoocclusive Pain and Impaired Vascular Function in Sickle Cell Anemia.

Blood ◽

10.1182/blood.v114.22.575.575 ◽

2009 ◽

Vol 114 (22) ◽

pp. 575-575 ◽

Cited By ~ 4

Author(s):

James G Taylor ◽

Inna Belfer ◽

Krupa Desai ◽

Victoria Youngblood ◽

Lita A. Freeman ◽

...

Keyword(s):

Sickle Cell ◽

Sickle Cell Anemia ◽

Vascular Function ◽

Odds Ratio ◽

Cell Injury ◽

Conflicts Of Interest ◽

Brown Norway ◽

Intracellular Camp ◽

No Production ◽

No Bioavailability

Abstract Abstract 575 Sickle cell anemia (SCA) is characterized by polymerization of sickle hemoglobin (HbS), erythrocyte deformity, and hemolytic anemia. HbS induced red cell injury is believed to be critical for initiating acute vasoocclusive episodes, although the precise mechanism underlying this has not been elucidated. Our prior work has established a SCA sub-phenotype characterized by hyper-hemolysis, decreased nitric oxide (NO) bioavailability, increase tricuspid jet velocity (TRV), and early mortality. Surprisingly, it was also characterized by fewer acute pain episodes. Recently, a haplotype of GTP cyclohydrolase (GCH1), the rate-limiting enzyme for tetrahydrobiopterin (BH4) synthesis, was associated with pain sensitivity in both animal and human experimental models. BH4 is a cofactor required for catecholamine, serotonin and NO production. Together, these findings led us to hypothesize that genetic variation resulting in uncoupled BH4 dependent enzymes might also modulate complications of SCA. We examined 7 markers of the GCH1 locus against interrelated traits, including hemolysis (LDH), NO bioavailability (arginine/ornithine ratios), TRV, painful episodes and survival among 188 contemporary SCA subjects followed at NIH. There was no association with LDH, arginine:ornithine ratios, TRV or survival at a median follow-up of 3.4 years. However, a GCH1 haplotype defined by 3 linked SNPs (rs8007267, rs2878172, rs7147286) was more prevalent in patients with more frequent pain compared to 73 SCA subjects with very infrequent painful episodes (odds ratio 2.13, 95% CI 1.21-3.78, P=0.007). Further evaluation in a replication study using the Cooperative Study of Sickle Cell Disease (CSSCD) database showed no association between pain and 2 of the GCH1 haplotype markers tested (rs8007267 P=0.59; rs2878172 P=0.35). However, analysis of 9 additional GCH1 SNPs in CSSCD cases indicated that an infrequent variant (rs17738966) is associated with pain (odds ratio 2.50, P=0.008). Further analysis for differences in population stratification, age, demographics and ascertainment bias is needed to better determine if GCH1 polymorphisms are associated with acute SCA pain. To study the possible functional significance of GCH1 polymorphisms, lymphoblastoid cell lines homozygous for these haplotype markers from the Yoruban Hapmap population were studied in vitro and had significantly lower GCH1 mRNA expression after stimulation to high levels of intracellular cAMP compared to homozygotes for the variant haplotype (P=0.004). In vivo, the GCH1 pain haplotype was also associated with diminished forearm blood vessel vasodilation in response to acetylcholine (ACh) infusion in 21 subjects with SCA (P=0.03). ACh induced vasodilation is an expected response to BH4 dependent endothelial NO synthesis and the variable SCA response suggests that those with a diminished vaso-relaxation have a relative BH4 deficiency. As a negative control, there was no association with nitroprusside induced vasodilation. Furthermore, examination of a congenic cross of Brown Norway chromosome 15 (site of rat Gch1) onto a Dahl SS background in rats demonstrated a chromosome dosage effect for ACh response (EC50, P#x003D;0.007). Taken together, we demonstrate an association between pain and a GCH1 haplotype in a contemporary SCA population, which also appears to involve a different haplotype effect than those previously described in non-SCA studies of pain. BH4 therapy has been studied in a Phase 2a clinical trial in SCD. The GCH1 association study with ACh dependent vasodilation in humans and animals suggests the need for additional studies to determine if polymorphisms in GCH1 and variability in BH4 synthesis modulates SCA pain, and if polymorphisms of this gene should be accounted for in clinical trials focused on pain prevention. Disclosures: No relevant conflicts of interest to declare.

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G6PD deficiency, absence of α-thalassemia, and hemolytic rate at baseline are significant independent risk factors for abnormally high cerebral velocities in patients with sickle cell anemia

Blood ◽

10.1182/blood-2008-03-143891 ◽

2008 ◽

Vol 112 (10) ◽

pp. 4314-4317 ◽

Cited By ~ 98

Author(s):

Françoise Bernaudin ◽

Suzanne Verlhac ◽

Sylvie Chevret ◽

Martine Torres ◽

Lena Coic ◽

...

Keyword(s):

Risk Factors ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

G6pd Deficiency ◽

Odds Ratio ◽

Multivariate Logistic Regression Analysis ◽

Multivariate Logistic Regression ◽

Alpha Thalassemia ◽

Independent Risk Factors ◽

First Time

AbstractStroke is predicted by abnormally high cerebral velocities by transcranial doppler (TCD). This study aimed at defining predictive factors for abnormally high velocities (≥ 2 m/sec) based on the Créteil pediatric sickle cell anemia (SCA) cohort composed of 373 stroke-free SCA children. α genes and β-globin haplotypes were determined. Biologic parameters were obtained at baseline. α-thalassemia was present in 155 of 325 and G6PD deficiency in 36 of 325 evaluated patients. TCD was abnormal in 62 of 373 patients. Multivariate logistic regression analysis showed that G6PD deficiency (odds ratio [OR] = 3.36, 95% confidence interval [CI] 1.10-10.33; P = .034), absence of alpha-thalassemia (OR = 6.45, 95% CI 2.21-18.87; P = .001), hemoglobin (OR per g/dL = 0.63, 95% CI 0.41-0.97; P = .038), and lactate dehydrogenase (LDH) levels (OR per IU/L = 1.001, 95% CI 1.000-1.002; P = .047) were independent risk factors for abnormally high velocities. This study confirms the protective effect of alpha-thalassemia and shows for the first time that G6PD deficiency and hemolysis independently increase the risk of cerebral vasculopathy.

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Adequacy of Vaccine Documentation Against Encapsulated Bacteria in a Population of Children with Sickle Cell Disease

Blood ◽

10.1182/blood.v118.21.4853.4853 ◽

2011 ◽

Vol 118 (21) ◽

pp. 4853-4853

Author(s):

Andrew S. Freiberg ◽

Antea C Singleton

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Sickle Cell Anemia ◽

Primary Care Physicians ◽

Conflicts Of Interest ◽

Pediatric Population ◽

Statistical Significance ◽

Retrospective Chart Review ◽

Cell Disease ◽

Encapsulated Bacteria

Abstract Abstract 4853 Immunization status is often used as an indicator of improved quality of health care and access in pediatric populations. The increased life expectancy in the general pediatric population has largely been attributed to the prevention of infectious disease through immunizations, and this fact is even truer for individuals with sickle cell disease. Adherence to recommended vaccination schedules against encapsulated bacteria in patients with sickle-cell anemia has not been well studied in any population. In order to determine documented compliance rates based on the current recommendations of the Department of Health and Human Services Center for Disease Control Immunization Schedules, a retrospective chart review was performed on 117 patients diagnosed with sickle cell anemia (HbSS) followed at the Penn State Hershey Children's Hospital Regional Pediatric Sickle Cell Center, through the year 2009. Since the vaccinations were given by each patient's primary provider(s), we attempted to obtain documentation of immunizations given by these providers, particularly against encapsulated bacteria. For 35 of the 117 patients, we were unable to obtain any forwarded documentation of any vaccinations. The vaccination schedules of the remaining 82 patients were audited for coverage against encapsulated bacteria. Only 16 of the 82 patients (19.5%) with forwarded documents demonstrated complete documented compliance, defined as having complete coverage against H. influenzae, N. meningitides, and S. pneumococcus. Of the remaining forwarded charts, 63 patients (76.8%) demonstrated some form of partial documented compliance, but four patients (4.9%) did not have documentation of vaccinations against any encapsulated bacteria despite documentation of receiving other vaccinations. Full documented compliance as indicated by forwarded records was most noted in children between the ages of 0–11.9 years (14/16 of patients with complete compliance). The proportion of adolescents without any forwarded documentation was larger than the younger age group; however, this difference did not reach statistical significance (p=0.36). Of the 82 patients whose primary care physicians forwarded documents, significantly more (14 of 34) adolescents (≥12 years of age) than children aged 0–11.9 years (8 of 48) were missing documentation of more than half of their vaccines (p=.014). These results indicate deficient documentation of vaccination coverage against encapsulated organisms, particularly in the adolescent population. To determine the clinical implications of these results, further studies detailing the demographics, socioeconomic status and correlations of such characteristics to morbidity and mortality should be completed. Disclosures: No relevant conflicts of interest to declare.

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