Early-onset indicators of a hypercoagulable state and clinical complications in a cohort of children with sickle cell trait.

Adults with sickle cell trait (SCT) have a procoagulant state with increased risk of thromboembolism, but limited data are available for children. We compared the coagulation profile of children with SCT, different sickle cell disease (SCD) genotypes, and healthy controls. Compared to controls and similarly to HbSC patients, 41 SCT children (mean age 6.85 years; 20 males; 88% Africans) had a characteristic procoagulant profile: higher levels of factor VIII, von Willebrand factor (VWF) Ag and CBA, D-dimer; lower levels of ADAMTS 13 activity, ADAMTS13 activity: VWFAg, plasminogen activator inhibitor, tissue plasminogen activator. Moreover, 13/41 had clinical complications of SCD, five requiring hospitalization.

Strenuous exercise in warm environment is associated with improved microvascular function in sickle cell trait.

PURPOSE: Sickle cell trait is characterized by the presence of both normal and abnormal haemoglobin in red blood cells. The rate of exertional collapse is increased in athletes and military recruits who carry the trait, particularly in stressful environmental conditions. The aim of the present study was to investigate microvascular function and its determinants in response to intense exercise at control and warm environmental temperatures in carriers (AS) and non-carriers (AA) of sickle cell trait. METHODS: Nine AS and 11 AA, all healthy physically active young men, randomly participated in four experimental sessions (rest at 21 °C and 31 °C and cycling at 21 °C and 31 °C). All participants performed three exercises bouts as follows: 18-min submaximal exercise; an incremental test to exhaustion; and three 30-s sprints spaced with 20-s resting intervals. RESULTS: Skin Blood Flow (SkBF) was similar at rest between AA and AS. SkBF for all participants was higher at 31 °C than 21 °C. It was significantly higher in the AS group compared to the AA group immediately after exercise, regardless of the environmental conditions. No significant differences in hemorheological parameters, muscle damage or cardiac injury biomarkers were observed between the two groups. Our data also suggest higher oxidative stress for the AS group, with high superoxide dismutase (P = 0.044 main group effect). CONCLUSION: A specific profile is identified in the AS population, with increased microvascular reactivity after maximal exercise in stressful environment and slight pro-/antioxidant imbalance.

Impact of Sickle Cell Trait Hemoglobin on the Intraerythrocytic Transcriptional Program of Plasmodium falciparum.

Sickle-trait hemoglobin (HbAS) confers nearly complete protection from severe, life-threatening falciparum malaria in African children. Despite this clear protection, the molecular mechanisms by which HbAS confers these protective phenotypes remain incompletely understood. As a forward genetic screen for aberrant parasite transcriptional responses associated with parasite neutralization in HbAS red blood cells (RBCs), we performed comparative transcriptomic analyses of Plasmodium falciparum in normal (HbAA) and HbAS erythrocytes during both in vitro cultivation of reference parasite strains and naturally occurring P. falciparum infections in Malian children with HbAA or HbAS. During in vitro cultivation, parasites matured normally in HbAS RBCs, and the temporal expression was largely unperturbed of the highly ordered transcriptional program that underlies the parasite's maturation throughout the intraerythrocytic development cycle (IDC). However, differential expression analysis identified hundreds of transcripts aberrantly expressed in HbAS, largely occurring late in the IDC. Surprisingly, transcripts encoding members of the Maurer's clefts were overexpressed in HbAS despite impaired parasite protein export in these RBCs, while parasites in HbAS RBCs underexpressed transcripts associated with the endoplasmic reticulum and those encoding serine repeat antigen proteases that promote parasite egress. Analyses of P. falciparum transcriptomes from 32 children with uncomplicated malaria identified stage-specific differential expression: among infections composed of ring-stage parasites, only cyclophilin 19B was underexpressed in children with HbAS, while trophozoite-stage infections identified a range of differentially expressed transcripts, including downregulation in HbAS of several transcripts associated with severe malaria in collateral studies. Collectively, our comparative transcriptomic screen in vitro and in vivo indicates that P. falciparum adapts to HbAS by altering its protein chaperone and folding machinery, oxidative stress response, and protein export machinery. Because HbAS consistently protects from severe P. falciparum, modulation of these responses may offer avenues by which to neutralize P. falciparum parasites. IMPORTANCE Sickle-trait hemoglobin (HbAS) confers nearly complete protection from severe, life-threatening malaria, yet the molecular mechanisms that underlie HbAS protection from severe malaria remain incompletely understood. Here, we used transcriptome sequencing (RNA-seq) to measure the impact of HbAS on the blood-stage transcriptome of Plasmodium falciparum in in vitro time series experiments and in vivo samples from natural infections. Our in vitro time series data reveal that, during its blood stage, P. falciparum's gene expression in HbAS is impacted primarily through alterations in the abundance of gene products as opposed to variations in the timing of gene expression. Collectively, our in vitro and in vivo data indicate that P. falciparum adapts to HbAS by altering its protein chaperone and folding machinery, oxidative stress response, and protein export machinery. Due to the persistent association of HbAS and protection from severe disease, these processes that are modified in HbAS may offer strategies to neutralize P. falciparum.

[Prevalence of sickle cell trait in blood donors at the regional blood transfusion center in the Haute Matsiatra Region, Madagascar]. / Prévalence du trait drépanocytaire chez les donneurs de sang au centre régional de transfusion sanguine de la région Haute Matsiatra, Madagascar.

INTRODUCTION: sickle cell trait is the heterozygous form of sickle-cell disease. Patients with sickle cell trait can synthesize normal hemoglobin A and hemoglobin S. This condition has no recognizable clinical signs; then subjects with sickle cell trait, ignoring their genetic status, can be found among blood donors. This can have severe impact on donors´ health status and on that of recipients, especially if these have sickle-cell trait. The purpose of our study is to determine the prevalence of sickle cell trait in blood donors. METHODS: we conducted a 4-month descriptive prospective study (January-May 2017) at the Haute Matsiatra Regional Blood Transfusion Center (RBTC). All donors were screened by Emmel test and positive cases were confirmed by hemoglobin electrophoresis. RESULTS: the study involved 427 donors, of whom 332 were men and 95 women (sex ratio 3.4). The average age of blood donors was 32.72, ranging from 18 to 64 years. Emmel test was positive in 5 donors (1.17%). These patients had the AS genotype confirmed by hemoglobin electrophoresis. CONCLUSION: the results of this study reveal the presence of sickle cell trait among blood donors at the CRTS. Most of them ignore their sickle cell status before blood donation. Quality and safety of blood and blood products are mandatory, hence the importance of screening among blood donors is a current relevant issue.

Pattern of haemoglobin phenotypes in newborn infants at the national hospital abuja using high performance liquid chromatography.

BACKGROUND: Haemoglobin (Hb) disorders are among the most common blood genetic disorders worldwide, and they constitute an important cause of morbidity and mortality, especially in Nigeria. Despite the clinical significance of early diagnosis, newborn screening for these conditions is not routinely done in Nigeria. OBJECTIVE: This study was undertaken to document the pattern of Hb phenotypes of newborn babies at the National Hospital Abuja and highlight the relevance of neonatal screening for early diagnosis of abnormal Hb phenotypes in Nigeria. SUBJECTS AND METHODS: A prospective study of eligible newborn babies delivered in the hospital at the study site was undertaken following parental informed consent. Venous blood was collected from the babies into an ethylenediaminetetraacetic acid sample bottles. The samples were analysed using high-performance liquid chromatography (HPLC) techniques, and the Hb phenotypes obtained were documented. Data were analysed using the Statistical Package for Social Sciences (SPSS) version 20 (IBM-SPSS, Armonk, NY, USA). RESULTS: Three hundred and eleven newborns (male = 173, female = 138) aged 0-28 days were recruited. Two hundred and thirty-six (75.9%) babies had Hb AA (FA) phenotype, 63 (20.3%) Hb AS (FAS), 6 (1.9%) Hb SS (FS), 4 (1.3%) Hb AC (FAC) and 2 (0.6%) had abnormal HbA variants. The overall prevalence of abnormal Hb phenotype was 24.1%. The results showed a significant association of sex (P = 0.003) and ethnicity (P = 0.047) with Hb phenotype. CONCLUSION: There is a wide spectrum of abnormal Hb phenotypes in Nigeria, and these phenotypes can easily be detected at birth using HPLC. We, therefore, recommend routine neonatal screening for sickle cell disease by HPLC in Nigeria.

Inhibition of Band 3 tyrosine phosphorylation: a new mechanism for treatment of sickle cell disease.

Many hypotheses have been proposed to explain how a glutamate to valine substitution in sickle haemoglobin (HbS) can cause sickle cell disease (SCD). We propose and document a new mechanism in which elevated tyrosine phosphorylation of Band 3 initiates sequelae that cause vaso-occlusion and the symptoms of SCD. In this mechanism, denaturation of HbS and release of heme generate intracellular oxidants which cause inhibition of erythrocyte tyrosine phosphatases, thus permitting constitutive tyrosine phosphorylation of Band 3. This phosphorylation in turn induces dissociation of the spectrin-actin cytoskeleton from the membrane, leading to membrane weakening, discharge of membrane-derived microparticles (which initiate the coagulation cascade) and release of cell-free HbS (which consumes nitric oxide) and activates the endothelium to express adhesion receptors). These processes promote vaso-occlusive events which cause SCD. We further show that inhibitors of Syk tyrosine kinase block Band 3 tyrosine phosphorylation, prevent release of cell-free Hb, inhibit discharge of membrane-derived microparticles, increase sickle cell deformability, reduce sickle cell adhesion to human endothelial cells, and enhance sickle cell flow through microcapillaries. In view of reports that imatinib (a Syk inhibitor) successfully treats symptoms of sickle cell disease, we suggest that Syk tyrosine kinase inhibitors warrant repurposing as potential treatments for SCD.

SPATIAL DISTRIBUTION OF NEWBORNS WITH SICKLE CELL TRAIT IN SERGIPE, BRAZIL.

OBJECTIVE: To use the spatial distribution of the sickle cell trait (SCT) to analyze the frequency of hemoglobin S (HbS) carriers in Sergipe. METHODS: The sample consisted of all individuals born in Sergipe from October 2011 to October 2012 who underwent neonatal screening in the public health system. Tests were carried out in basic health units and forwarded to the University Hospital laboratory, where they were analyzed. We used spatial autocorrelation (Moran's index) to assess the spatial distribution of heterozygous individuals with hemoglobinopathies. RESULTS: Among 32,906 newborns, 1,202 showed other types of hemoglobin besides Hemoglobin A. We found a positive correlation between the percentage of black and multiracial people and the incidence of SCT. Most SCT cases occurred in the cities of Aracaju (n=273; 22.7%), Nossa Senhora do Socorro (n=102; 8.4%), São Cristóvão (n=58; 4.8%), Itabaiana (n=39; 4.2%), Lagarto (n=37; 4.01%), and Estância (n=46; 4.9%). CONCLUSIONS: The spatial distribution analysis identified regions in the state with a high frequency of HbS carriers. This information is important health care planning. This method can be applied to detect other places that need health units to guide and care for sickle cell disease patients and their families.

Prevalence of Hemoglobinopathies (ß-Thalassemia and Sickle Cell Trait) in the Adult Population of Al Majma'ah, Saudi Arabia.

Despite the high prevalence of hemoglobinopathies in Saudi Arabia, the prevalence data in some regions are lacking. Updating the epidemiological survey of hemoglobinopathies at regular intervals is necessary to develop effective prevention and control strategies. Therefore, the primary aim of this study was to determine the prevalence of selected hemoglobinopathies in Saudi adults attending premarital screening at the King Khaled General Hospital (KKGH), Al Majma'ah, Saudi Arabia. The current retrospective study was approved by the Central Institutional Review Board (IRB) of the Ministry of Health (with central IRB log #2019-0039E) and was carried out at the above hospital. The data of the premarital couples, who attended the premarital screening center at KKGH from 1 October 2016 to 30 September 2019, was included in this study. A cation exchange high performance liquid chromatography (HPLC) system was used for screening of the selected hemoglobinopathies. In total, 3755 cases including 1953 (52.01%) males and 1802 (47.99%) females, were screened for hemoglobinopathies. Abnormal hemoglobin (Hb) fractions were observed in 38 (1.01%) cases. The prevalence of ß-thalassemia (ß-thal) trait was 0.69% (26/3755) and that of sickle cell trait 0.32% (12/3755). Our results showed that the prevalence of ß-thal trait is higher than that of sickle cell trait in the adult population of Al Majma'ah. Further comprehensive programs should be carried out to determine the prevalence of hemoglobinopathies in various provinces and cities of Saudi Arabia and other countries. This will help to maintain the updated records of the disease incidence for improving the control measures.

5-(Hydroxymethyl)furfural restores low-oxygen rheology of sickle trait blood in vitro.

Sickle cell trait (SCT) is the benign heterozygous carrier state for the sickle variant of the HBB gene. Most of the ~300 million people with SCT worldwide will not experience any significant complications. However, accumulating evidence finds SCT associated with increased risk for the common conditions of chronic kidney disease and venous thromboembolism, and severe but rare renal medullary carcinoma and exercise-induced rhabdomyolysis. The mechanism is uncertain, but probably involves pathological rheology of SCT blood in regions of low oxygen tension, resulting from sickle haemoglobin polymerization in SCT red cells and leading to reduced blood flow and further tissue hypoxia and damage. Here, we used an in vitro microfluidic flow system to study the oxygen-dependent rheology of SCT blood and show that 5-(hydroxymethyl)furfural, a natural breakdown product of glucose and fructose-containing foods, such as fruit juices, can reduce the effects of hypoxia on SCT blood rheology in vitro, restoring near-normal flow velocities at very low oxygen. While opinions regarding the clinical significance of the risks associated with SCT are still evolving, these results suggest that a compound present in some food may provide a potential approach for managing risks that may be associated with SCT.

Triglyceride/HDL-cholesterol ratio and plasminogen activator inhibitor-1 independently predict high pulse pressure in sickle cell trait and disease.

We hypothesised that TG/HDL-C ratio and PAI-1 would be associated with high pulse pressure (PP) in young adults with sickle cell trait (SCT) and sickle cell disease (SCD). We compared the clinical, biochemical, and cardiometabolic parameters among individuals with normal genotype (HbAA; n = 60), SCT (HbAS; n = 60), and SCD (HbSS; n = 60), all in steady state. Using multivariate linear regression analysis, high PP was positively related to TG/HDL-C ratio in SCT (ß = 0.307; p = .014) and PAI-1 (ß = 0.499; p = .001) in SCD. The curve of receiver operating characteristic also showed that TG/HDL-C ratio and PAI-1 are efficient predictors of high PP in SCT carriers and SCD patients, respectively. This study suggests that increased levels of TG/HDL-C ratio and PAI-1 may be salient risk factors that would promote the development of arterial stiffness and other CVD in SCT carriers and SCD patients.

Spatial distribution of newborns with sickle cell trait in sergipe, brazil / Distribuição espacial de recém-nascidos com traço falciforme em sergipe

ABSTRACT Objective: To use the spatial distribution of the sickle cell trait (SCT) to analyze the frequency of hemoglobin S (HbS) carriers in Sergipe. Methods: The sample consisted of all individuals born in Sergipe from October 2011 to October 2012 who underwent neonatal screening in the public health system. Tests were carried out in basic health units and forwarded to the University Hospital laboratory, where they were analyzed. We used spatial autocorrelation (Moran's index) to assess the spatial distribution of heterozygous individuals with hemoglobinopathies. Results: Among 32,906 newborns, 1,202 showed other types of hemoglobin besides Hemoglobin A. We found a positive correlation between the percentage of black and multiracial people and the incidence of SCT. Most SCT cases occurred in the cities of Aracaju (n=273; 22.7%), Nossa Senhora do Socorro (n=102; 8.4%), São Cristóvão (n=58; 4.8%), Itabaiana (n=39; 4.2%), Lagarto (n=37; 4.01%), and Estância (n=46; 4.9%). Conclusions: The spatial distribution analysis identified regions in the state with a high frequency of HbS carriers. This information is important health care planning. This method can be applied to detect other places that need health units to guide and care for sickle cell disease patients and their families.

RESUMO Objetivo: Basear-se na distribuição espacial do traço falciforme (TF) para analisar a frequência dos portadores da hemoglobina S (HbS) em Sergipe. Métodos: A amostra foi constituída por todos os indivíduos nascidos em Sergipe, no período de outubro de 2011 a outubro de 2012, submetidos à triagem neonatal pelo Sistema Único de Saúde, ano de início da triagem universal no Estado. Os testes foram realizados em unidades básicas de saúde e encaminhados para o laboratório do Hospital Universitário, onde foram analisados. A análise da distribuição espacial dos indivíduos heterozigotos para hemoglobinopatias foi realizada por autocorrelação espacial (índice de Moran). Resultados: Dentre os 32.906 recém-nascidos estudados, 1.202 apresentaram outras hemoglobinas além da Hemoglobina A. Houve correlação positiva entre a porcentagem de negros e mestiços e a incidência de TF. A maioria dos casos foi encontrada nos municípios de Aracaju (n=273; 22,7%), Nossa Senhora do Socorro (n=102; 8,4%), São Cristóvão (n=58; 4,8%), Itabaiana (n=39; 4,2%), Lagarto (n=37; 4,01%) e Estância (n=46; 4,9%). Conclusões: Na análise de distribuição espacial por autocorrelação, identificaram-se regiões no Estado com maior frequência de HbS, o que é de extrema importância para o planejamento do sistema de saúde, podendo a mesma metodologia ser aplicada para identificação de outros locais com maior necessidade de centros para cuidados e orientações a portadores de doença falciforme e seus familiares.

Thirty-year risk of ischemic stroke in individuals with sickle cell trait and modification by chronic kidney disease: The atherosclerosis risk in communities (ARIC) study.

Sickle cell trait (SCT) has been associated with hypercoagulability, chronic kidney disease (CKD), and ischemic stroke. Whether concomitant CKD modifies long-term ischemic stroke risk in individuals with SCT is uncertain. We analyzed data from 3602 genotyped black adults (female = 62%, mean baseline age = 54 years) who were followed for a median 26 years by the Atherosclerosis Risk in Communities Study. Ischemic stroke was verified by physician review. Associations between SCT and ischemic stroke were analyzed using repeat-events Cox regression, adjusted for potential confounders. SCT was identified in 236 (7%) participants, who more often had CKD at baseline than noncarriers (18% vs 13%, P = .02). Among those with CKD, elevated factor VII activity was more prevalent with SCT genotype (36% vs 22%; P = .05). From 1987-2017, 555 ischemic strokes occurred in 436 individuals. The overall hazard ratio of ischemic stroke associated with SCT was 1.31 (95% CI: 0.95-1.80) and was stronger in participants with concomitant CKD (HR = 2.18; 95% CI: 1.16-4.12) than those without CKD (HR = 1.09; 95% CI: 0.74-1.61); P for interaction = .04. The hazard ratio of composite ischemic stroke and/or death associated with SCT was 1.20 (95% CI: 1.01-1.42) overall, 1.44 (95% CI: 1.002-2.07) among those with CKD, and 1.15 (95% CI: 0.94-1.39) among those without CKD; P for interaction = .18. The long-term risk of ischemic stroke associated with SCT relative to noncarrier genotype appears to be modified by concomitant CKD.

Fetal Hemoglobin Modulators May Be Associated With Symptomology of Football Players with Sickle Cell Trait.

OBJECTIVES: This study investigates whether genetic modifiers previously shown to influence adult fetal hemoglobin (HbF) levels and glucose-6-phosphate dehydrogenase deficiency were associated with variable symptomology in a small sample of collegiate football players with sickle cell trait. METHODS: Survey data on self-assessed symptoms and genotype data from five single nucleotide polymorphisms (SNPs) related to HbF production and two SNPs that cause glucose-6-phosphate dehydrogenase deficiency were collected from current and former college football players. RESULTS: In this sample, SNPs found within the ß-globin gene cluster were found to be associated with a previous diagnosis of exertional sickling and experience of extreme heat during and after training. rs10189857 in the BCL11A gene was associated with body mass index and weight and with experiencing extreme thirst during and after training. No significant correlations were found between the other SNPs and symptoms within this sample. CONCLUSIONS: These findings show that genetic variation known to affect sickle cell disease symptomology may partly explain why some football players with sickle cell trait experience adverse clinical outcomes during periods of extreme physical exertion and others do not.

Serious adverse events in African-American cancer patients with sickle cell trait and inherited haemoglobinopathies in a SEER-Medicare claims cohort.

African-American (AA) cancer patients have long-experienced worse outcomes compared to non-Hispanic whites (NHW). No studies to date have evaluated the prognostic impact of sickle cell trait (SCT) and other inherited haemoglobinopathies, of which several are disproportionately high in the AA population. In a cohort analysis of treated patients diagnosed with breast or prostate cancer in the linked SEER-Medicare database, the relative risk (RR) for ≥1 serious adverse events (AEs), defined as hospitalisations or emergency department visits, was estimated for 371 AA patients with a haemoglobinopathy (AA+) compared to patients without haemoglobinopathies (17,303 AA-; 144,863 NHW-). AA+ patients had significantly increased risk for ≥1 AEs compared to AA- (RR = 1.19; 95% CI 1.11-1.27) and NHW- (RR = 1.23; 95% CI 1.15-1.31) patients. The magnitude of effect was similar by cancer type, and in analyses of AA+ with SCT only. Our findings suggest a novel hypothesis for disparities in cancer outcomes.

Evaluation of agreement between hemoglobin A1c, fasting glucose, and fructosamine in Senegalese individuals with and without sickle-cell trait.

Fasting glucose (FG) and glycated hemoglobin A1c (HbA1c) perform sub-optimally in people of African origin, especially in individuals with sickle-cell trait (SCT). The purpose of this study was to compare the relationships between HbA1c, FG, and fructosamine in individuals from Senegal with and without SCT. HbA1c, FG, and fructosamine were measured in 203 adults from Senegal (100 control: 45 with type 2 diabetes (T2D); 103 SCT: 51 with T2D). Significant, positive correlations were observed between HbA1c and FG, fructosamine and FG, and fructosamine and HbA1c in both groups. The limits of agreement were inappropriately large in both groups for the Bland-Altman plots of HbA1c and FG (control: -95.97 to 83.97%; SCT: -115.9 to 91.52%), fructosamine and FG (control: -100.6 to 99.89%; SCT: -105.6 to 100.6%), and fructosamine and HbA1c (control: -52.03 to 38.98%; SCT: -88.04 to 71.41%). In both groups, the greatest proportion of subjects were considered above the clinical cut-point for hyperglycemia when fructosamine was used as the criterion (control: 33%; SCT: 44.6%), and the lowest percentage of subjects were classified as over the clinical cut-point when HbA1c was used as the criterion (control: 21%; SCT: 27.7%).Substantial disparities between HbA1c, FG, and fructosamine were observed in both groups, and these differences were exaggerated in the SCT group. Therefore, these three biomarkers should not be considered to be interchangeable measures of glycemic control. These biomarkers should be used thoughtfully, and special care should be taken when using them in individuals with SCT.