Global burden of sickle cell anaemia in children under five, 2010-2050: modelling based on demographics, excess mortality, and interventions

Sickle cell disease in western Sudan: genetic epidemiology and predictors of knowledge attitude and practices

OBJECTIVE

To investigate the epidemiology of sickle cell disease (SCD) and determinants of knowledge, attitudes and practices (KAP) towards SCD in western Kordofan State, Sudan.

METHODS

A community-based, descriptive, cross-sectional study was conducted in three towns. Three hundred and seventy-two households were polled, and blood samples for haemoglobin phenotyping were collected from 1116 individuals. Sociodemographic, socio-economic and KAP data were collected using investigator-administered questionnaires. Descriptive, frequency distribution and multiple regression analyses were performed.

RESULTS

About 50.9% of the study population were Misseriya tribes. Consanguineous marriages were reported by 67.5% of the households. The highest percentage of homozygous SCD was 2.8% among children under 5 years of age. About 24.9% were carriers of HbS allele (HbAS). HbS allele frequency was highest in children aged 5-11 years (18.3%, CI: 13.7-22.9%) and lowest in males >15 years old (12.0%, CI: 6.1-17.9%). The average HbS frequency across all age groups was 14.5% (95% CI: 12.2-16.8%). The most frequent β-globin gene cluster haplotype was the Cameroon (30.8%), followed by the Benin (21.8%), the Senegal (12.8%) and the Bantu (2.2%) haplotypes. About 17.0% of all-cause child deaths were due to SCD. The estimated change in log odds of having the SS genotype per year increase in age was (-) 0.0058 (95% CI -0.0359, 0.0242). This represents a non-statistically significant 2.9% increase in 5-year mortality for individuals with the SS genotype relative to those with AS and AA genotypes. About 46.9% of the households had poor knowledge, 26.1% had satisfactory knowledge, and 26.9% had good knowledge about sickle cell disease. Mothers' and fathers' educational levels were significant predictors of good knowledge about SCD (P < 0.05). About 48.0% had a satisfactory attitude towards sickle cell disease while 30.7% had poor attitude and only 21.3 showed good attitudes. Poor knowledge about SCD and low socio-economic status were the strongest positive predictors of poor attitude and practices towards SCD (P < 0.01).

CONCLUSIONS

Sickle cell disease is a major health problem in West Kordofan, Sudan. Knowledge, attitude and practices towards the disease are not satisfactory. The development of public health programs is highly recommended to control and manage SCD in western parts of Sudan.

Nonhematopoietic Nrf2 dominantly impedes adult progression of sickle cell anemia in mice

The prevention of organ damage and early death in young adults is a major clinical concern in sickle cell disease (SCD). However, mechanisms that control adult progression of SCD during the transition from adolescence are poorly defined with no cognate prophylaxis. Here, we demonstrate in a longitudinal cohort of homozygous SCD (SS) mice a link between intravascular hemolysis, vascular inflammation, lung injury, and early death. Prophylactic Nrf2 activation in young SS mice stabilized intravascular hemolysis, reversed vascular inflammation, and attenuated lung edema in adulthood. Enhanced Nrf2 activation in endothelial cells in vitro concurred with the dramatic effect on vascular inflammation in the mice. BM chimeric SS mice lacking Nrf2 expression in nonhematopoietic tissues were created to dissect the role of nonerythroid Nrf2 in SCD progression. The SS chimeras developed severe intravascular hemolysis despite having erythroid Nrf2. In addition, they developed premature vascular inflammation and pulmonary edema and died younger than donor littermates with intact nonhematopoietic Nrf2. Our results reveal a dominant protective role for nonhematopoietic Nrf2 against tissue damage in both erythroid and nonerythroid tissues in SCD. Furthermore, we show that prophylactic augmentation of Nrf2-coordinated cytoprotection effectively impedes onset of the severe adult phenotype of SCD in mice.

Family, Community, and Health System Considerations for Reducing the Burden of Pediatric Sickle Cell Disease in Uganda Through Newborn Screening

Sickle cell disease (SCD) is associated with high mortality for children under 5 years of age in sub-Saharan Africa. Newborn sickle screening program and enhanced capacity for SCD treatment are under development to reduce disease burden in Uganda and elsewhere in the region. Based on an international stakeholder meeting and a family-directed conference on SCD in Kampala in 2015, and interviews with parents, multinational experts, and other key informants, we describe health care, community, and family perspectives in support of these initiatives. Key stakeholder meetings, discussions, and interviews were held to understand perspectives of public health and multinational leadership, patients and families, as well as national progress, resource needs, medical and social barriers to program success, and resources leveraged from HIV/AIDS. Partnering with program leadership, professionals, patients and families, multinational stakeholders, and leveraging resources from existing programs are needed for building successful programs in Uganda and elsewhere in sub-Saharan Africa.

Customizing the genome as therapy for the β-hemoglobinopathies

Despite nearly complete understanding of the genetics of the β-hemoglobinopathies for several decades, definitive treatment options have lagged behind. Recent developments in technologies for facile manipulation of the genome (zinc finger nucleases, transcription activator-like effector nucleases, or clustered regularly interspaced short palindromic repeats-based nucleases) raise prospects for their clinical application. The use of genome-editing technologies in autologous CD34(+) hematopoietic stem and progenitor cells represents a promising therapeutic avenue for the β-globin disorders. Genetic correction strategies relying on the homology-directed repair pathway may repair genetic defects, whereas genetic disruption strategies relying on the nonhomologous end joining pathway may induce compensatory fetal hemoglobin expression. Harnessing the power of genome editing may usher in a second-generation form of gene therapy for the β-globin disorders.

Sickle Cell Disease in Sub-Saharan Africa

In Africa, at least 240,000 children are born each year with sickle cell disease. Historically, in the absence of newborn screening and appropriate treatment, most such children died undiagnosed in early childhood. However, with increasing awareness of the condition and economic and epidemiologic transition, increasing numbers are surviving. Greater investments in basic and applied research in the African context, and increased sensitization or African ministries of health regarding the importance of this condition, could make a substantial difference to the lives and livelihoods of millions of people living with sickle cell disease on the continent and their families.

Newborn Screening for Sickle Cell Disease in Liberia: A Pilot Study

BACKGROUND

In malaria-endemic countries in West Africa, sickle cell disease (SCD) contributes to childhood mortality. Historically, Liberia had regions wherein hemoglobin S and beta-thalassemia trait were mutually exclusive. Data on hemoglobinopathies in the Monrovia, the capital, are outdated and do not reflect urban migration. Updating the epidemiology of SCD is necessary to plan a public health and clinical agenda. Neither newborn screening (NBS) nor screening tools were available in country. This pilot study aimed to determine the feasibility of NBS using a South-South partnership and define the incidence of sickle cell trait (SCT) and SCD in Monrovia.

PROCEDURE

This descriptive epidemiologic feasibility study collected dried blood spots from 2,785 consecutive newborns delivered at a hospital in Monrovia. Samples were analyzed by isoelectric focusing at a regional reference laboratory. Infants with SCD were referred for preventive care.

RESULTS

SCT occurred in 10.31% of infants screened. SCD occurred in 33 infants screened [1.19% (95% confidence interval [CI]: 0.79-1.59%)] (FS: 28/33, FSB: 2/33, FSA: 2/33, FSX: 1/33). There were no infants with FSC phenotype observed. Nonsickling hemoglobin phenotypes "FC" and "F" were each present in three infants screened. Seventy-six percent of infants with SCD were brought to care, demonstrating the feasibility of our approach.

CONCLUSIONS

The incidence of SCD and other hemoglobinopathies remains high in Liberia. Additional studies are needed to clarify sickle genotypes and identify the contribution of silent beta-thalassemia alleles. By developing regional partnerships, countries similar to Liberia can acquire current data to inform NBS as an important public health initiative toward improving child health.

Edible insects are the future?

The global increase in demand for meat and the limited land area available prompt the search for alternative protein sources. Also the sustainability of meat production has been questioned. Edible insects as an alternative protein source for human food and animal feed are interesting in terms of low greenhouse gas emissions, high feed conversion efficiency, low land use, and their ability to transform low value organic side streams into high value protein products. More than 2000 insect species are eaten mainly in tropical regions. The role of edible insects in the livelihoods and nutrition of people in tropical countries is discussed, but this food source is threatened. In the Western world, there is an increasing interest in edible insects, and examples are given. Insects as feed, in particular as aquafeed, have a large potential. Edible insects have about the same protein content as conventional meat and more PUFA. They may also have some beneficial health effects. Edible insects need to be processed and turned into palatable dishes. Food safety may be affected by toxicity of insects, contamination with pathogens, spoilage during conservation and allergies. Consumer attitude is a major issue in the Western world and a number of strategies are proposed to encourage insect consumption. We discuss research pathways to make insects a viable sector in food and agriculture: an appropriate disciplinary focus, quantifying its importance, comparing its nutritional value to conventional protein sources, environmental benefits, safeguarding food safety, optimising farming, consumer acceptance and gastronomy.

Prevalence of Sickle Cell Trait in the Southern Suburb of Beirut, Lebanon

Objective

The objective of this study was to assess the prevalence, gender differences, and time trends of Sickle Cell Trait in the Southern Suburb of Beirut, Lebanon, as well as to highlight the importance of screening for Sickle Cell Trait carriers in this population. Another objective was to describe a new screening technique for Sickle Cell Trait carriers.

Methods

This was a retrospective cohort study carried out at a private laboratory in the Southern Suburb of Beirut, Lebanon between 2002 and 2014. The sickling test was carried out for each patient using two methods: the classical “sodium metabisulfite sickling test”, and the new “sickling test method” used in the private lab. As a confirmatory test, hemoglobin electrophoresis was run on a random sample of 223 cases which were found to be positive using the two sickling tests.

Results

A total of 899 cases were found to be positive for the sickle cell trait out of 184,105 subjects screened during the 12-year period, prevalence = 0.49% (95% CI: 0.46 – 0.52). Among the total sample, females were found to have higher prevalence, where no time trend over the studied period was noted. The haemoglobin electrophoresis method confirmed the results of this new sickling test technique among the random sample of the 223 cases.

Conclusion

We found that the prevalence of sickle cell trait is lower as compared to other Arab countries, higher in females, with no significant time trend. The sickle cell test was found to be an accurate, simple and cheap test that could be easily added as a requirement for the pre-marital testing to screen for Sickle Cell Trait carriers.

Central nervous system complications and management in sickle cell disease

With advances in brain imaging and completion of randomized clinical trials (RCTs) for primary and secondary stroke prevention, the natural history of central nervous system (CNS) complications in sickle cell disease (SCD) is evolving. In order of current prevalence, the primary CNS complications include silent cerebral infarcts (39% by 18 years), headache (both acute and chronic: 36% in children with sickle cell anemia [SCA]), ischemic stroke (as low as 1% in children with SCA with effective screening and prophylaxis, but ∼11% in children with SCA without screening), and hemorrhagic stroke in children and adults with SCA (3% and 10%, respectively). In high-income countries, RCTs (Stroke Prevention in Sickle Cell Anemia [STOP], STOP II) have demonstrated that regular blood transfusion therapy (typically monthly) achieves primary stroke prevention in children with SCA and high transcranial Doppler (TCD) velocities; after at least a year, hydroxycarbamide may be substituted (TCD With Transfusions Changing to Hydroxyurea [TWiTCH]). Also in high-income countries, RCTs have demonstrated that regular blood transfusion is the optimal current therapy for secondary prevention of infarcts for children with SCA and strokes (Stroke With Transfusions Changing to Hydroxyurea [SWiTCH]) or silent cerebral infarcts (Silent Infarct Transfusion [SIT] Trial). For adults with SCD, CNS complications continue to be a major cause of morbidity and mortality, with no evidence-based strategy for prevention.

Complications of sickle cell anaemia in children in Northwestern Tanzania

OBJECTIVES

Tanzania has the third highest birth rate of sickle cell anaemia (SCA) in Africa, but few studies describe severity of complications or available treatments, especially in Northwest Tanzania around Lake Victoria where the sickle gene is most prevalent. This is a report of the spectrum of clinical disease and range of interventions available at Bugando Medical Centre (Bugando) in Northwest Tanzania in Africa.

METHODS

A cross-sectional study was carried out in Bugando between 1 August 2012 and 30 September 2012. Children (<15 years old) with SCA attending Bugando were sequentially enrolled. A trained research assistant completed a Swahili questionnaire with the parent or guardian of each participant concerning demographic information, clinical features of disease, and treatments received.

RESULTS

Among the 124 participants enrolled, the median age was 6 years (interquartile range [IQR] 4-8.5), and only 13 (10.5%) were < 3 years old. Almost all participants (97.6%) had a prior history of a vaso-occlusive episode, 83 (66.9%) had prior acute chest syndrome, and 21 (16.9%) had prior stroke. In the preceding 12 months, 120 (96.8%) had been hospitalized, and a vaso-occlusive episode was the most common reason for hospitalization (35.5%). Prescriptions for folic acid (92.7%) and malaria prophylaxis (84.7%) were common, but only one had received a pneumococcal vaccine, and none had received hydroxyurea or prophylactic penicillin.

CONCLUSION

Children with SCA receiving care in Tanzania are diagnosed late, hospitalized frequently, and have severe complications. Opportunities exist to improve care through wider access to screening and diagnosis as well as better coordination of comprehensive care.

Sickle cell disease and H3Africa: enhancing genomic research on cardiovascular diseases in African patients

Background

Sickle cell disease (SCD) has a high prevalence in sub-Saharan Africa. There are several cardiovascular phenotypes in SCD that contribute to its morbidity and mortality.

Discussion

SCD is characterised by marked clinical variability, with genetic factors playing key modulating roles. Studies in Tanzania and Cameroon have reported that singlenucleotide polymorphisms in BCL11A and HBS1L-MYB loci and co-inheritance of alpha-thalassaemia impact on foetal haemoglobin levels and clinical severity. The prevalence of overt stroke among SCD patients in Cameroon (6.7%) and Nigeria (8.7%) suggests a higher burden than in high-income countries. There is also some evidence of high burden of kidney disease and pulmonary hypertension in SCD; however, the burden and genetics of these cardiovascular conditions have seldom been investigated in Africa.

Conclusions

Several H3Africa projects are focused on cardiovascular diseases and present major opportunities to build genome-based research on existing SCD platforms in Africa to transform the health outcomes of patients.

Transcription factors LRF and BCL11A independently repress expression of fetal hemoglobin

Genes encoding human β-type globin undergo a developmental switch from embryonic to fetal to adult-type expression. Mutations in the adult form cause inherited hemoglobinopathies or globin disorders, including sickle cell disease and thalassemia. Some experimental results have suggested that these diseases could be treated by induction of fetal-type hemoglobin (HbF). However, the mechanisms that repress HbF in adults remain unclear. We found that the LRF/ZBTB7A transcription factor occupies fetal γ-globin genes and maintains the nucleosome density necessary for γ-globin gene silencing in adults, and that LRF confers its repressive activity through a NuRD repressor complex independent of the fetal globin repressor BCL11A. Our study may provide additional opportunities for therapeutic targeting in the treatment of hemoglobinopathies.

Validation of a Low-Cost Paper-Based Screening Test for Sickle Cell Anemia

Background

The high childhood mortality and life-long complications associated with sickle cell anemia (SCA) in developing countries could be significantly reduced with effective prophylaxis and education if SCA is diagnosed early in life. However, conventional laboratory methods used for diagnosing SCA remain prohibitively expensive and impractical in this setting. This study describes the clinical validation of a low-cost paper-based test for SCA that can accurately identify sickle trait carriers (HbAS) and individuals with SCA (HbSS) among adults and children over 1 year of age.

Methods and Findings

In a population of healthy volunteers and SCA patients in the United States (n = 55) the test identified individuals whose blood contained any HbS (HbAS and HbSS) with 100% sensitivity and 100% specificity for both visual evaluation and automated analysis, and detected SCA (HbSS) with 93% sensitivity and 94% specificity for visual evaluation and 100% sensitivity and 97% specificity for automated analysis. In a population of post-partum women (with a previously unknown SCA status) at a primary obstetric hospital in Cabinda, Angola (n = 226) the test identified sickle cell trait carriers with 94% sensitivity and 97% specificity using visual evaluation (none of the women had SCA). Notably, our test permits instrument- and electricity-free visual diagnostics, requires minimal training to be performed, can be completed within 30 minutes, and costs about $0.07 in test-specific consumable materials.

Conclusions

Our results validate the paper-based SCA test as a useful low-cost tool for screening adults and children for sickle trait and disease and demonstrate its practicality in resource-limited clinical settings.

Hydroxyurea Therapy for Children With Sickle Cell Anemia in Sub-Saharan Africa: Rationale and Design of the REACH Trial

BACKGROUND

Sickle cell anemia (SCA) is an inherited hematological disorder that causes a large but neglected global health burden, particularly in Africa. Hydroxyurea represents the only available disease-modifying therapy for SCA, and has proven safety and efficacy in high-resource countries. In sub-Saharan Africa, there is minimal use of hydroxyurea, due to lack of data, absence of evidence-based guidelines, and inexperience among healthcare providers.

PROCEDURE

A partnership was established between investigators in North America and sub-Saharan Africa, to develop a prospective multicenter research protocol designed to provide data on the safety, feasibility, and benefits of hydroxyurea for children with SCA.

RESULTS

The Realizing Effectiveness Across Continents with Hydroxyurea (REACH, ClinicalTrials.gov NCT01966731) trial is a prospective, phase I/II open-label dose escalation study of hydroxyurea that will treat a total of 600 children age 1-10 years with SCA: 150 at each of four different clinical sites within sub-Saharan Africa (Angola, Democratic Republic of Congo, Kenya, and Uganda). The primary study endpoint will be severe hematological toxicities that occur during the fixed-dose treatment phase. REACH has an adaptive statistical design that allows for careful assessment of toxicities to accurately identify a safe hydroxyurea dose.

CONCLUSIONS

REACH will provide data that address critical gaps in knowledge for the treatment of SCA in sub-Saharan Africa. By developing local expertise with the use of hydroxyurea and helping to establish treatment guidelines, the REACH trial results will have the potential to transform care for children with SCA in Africa.

PRIMARY STROKE PREVENTION IN CHILDREN WITH SICKLE CELL ANEMIA LIVING IN AFRICA: THE FALSE CHOICE BETWEEN PATIENT-ORIENTED RESEARCH AND HUMANITARIAN SERVICE

In the United States, primary stroke prevention in children with sickle cell anemia (SCA) is now the standard of care and includes annual transcranial Doppler ultrasound evaluation to detect elevated intracranial velocities; and for those at risk, monthly blood transfusion therapy for at least a year followed by the option of hydroxyurea therapy. This strategy has decreased stroke prevalence in children with SCA from approximately 11% to 1%. In Africa, where 80% of all children with SCA are born, no systematic approach exists for primary stroke prevention. The two main challenges for primary stroke prevention in children with SCA in Africa include: 1) identifying an alternative to blood transfusion therapy, because safe monthly blood transfusion therapy is not feasible; and 2) assembling a health care team to implement and expand this effort. We will emphasize early triumphs and challenges to decreasing the incidence of strokes in African children with SCA.

Comparative Analysis of Iron Homeostasis in Sub-Saharan African Children with Sickle Cell Disease and Their Unaffected Siblings

Iron is an essential trace element subject to tight regulation to ensure adequate running of biological processes. In sub-Saharan Africa where hemoglobinopathies are common, iron homeostasis is likely to be impaired by these conditions. Here, we assessed and compared key serum proteins associated with iron metabolism between sub-Saharan African children with sickle cell disease (SCD) and their unaffected siblings. Complete blood counts and serum concentrations of four key proteins involved in iron regulation (ferritin, transferrin, sTfR, and hepcidin) were measured for 73 children with SCD and 68 healthy siblings in Benin, West Africa. We found significant differences in concentration of transferrin, sTfR, and ferritin between the two groups. Hepcidin concentrations were found at unusually high concentrations but did not differ among the two groups. We found a significant negative correlation between hepcidin levels and both MCH and MCV in the SCD group and report that sTfR concentrations show a correlation with MCV and MHC in opposite directions in the two groups. These results highlight the unusually high levels of hepcidin in the Beninese population and the patterns of differential iron homeostasis taking place under SCD status. These results lay the foundation for a systematic evaluation of the underlying mechanisms deregulating iron homeostasis in populations with SCD or high prevalence of iron deficiency.

Coagulation abnormalities of sickle cell disease: Relationship with clinical outcomes and the effect of disease modifying therapies

Sickle cell disease (SCD) is a hypercoagulable state. Patients exhibit increased platelet activation, high plasma levels of markers of thrombin generation, depletion of natural anticoagulant proteins, abnormal activation of the fibrinolytic system, and increased tissue factor expression, even in the non-crisis "steady state." Furthermore, SCD is characterized by an increased risk of thrombotic complications. The pathogenesis of coagulation activation in SCD appears to be multi-factorial, with contributions from ischemia-reperfusion injury and inflammation, hemolysis and nitric oxide deficiency, and increased sickle RBC phosphatidylserine expression. Recent studies in animal models suggest that activation of coagulation may contribute to the pathogenesis of SCD, but the data on the contribution of coagulation and platelet activation to SCD-related complications in humans are limited. Clinical trials of new generations of anticoagulants and antiplatelet agents, using a variety of clinical endpoints are warranted.

Role of innate immunity-triggered pathways in the pathogenesis of Sickle Cell Disease: a meta-analysis of gene expression studies

Despite the detailed characterization of the inflammatory and endothelial changes observed in Sickle Cell Disease (SCD), the hierarchical relationship between elements involved in the pathogenesis of this complex disease is yet to be described. Meta-analyses of gene expression studies from public repositories represent a novel strategy, capable to identify key mediators in complex diseases. We performed several meta-analyses of gene expression studies involving SCD, including studies with patient samples, as well as in-vitro models of the disease. Meta-analyses were performed with the Inmex bioinformatics tool, based on the RankProd package, using raw gene expression data. Functional gene set analysis was performed using more than 60 gene-set libraries. Our results demonstrate that the well-characterized association between innate immunity, hemostasis, angiogenesis and heme metabolism with SCD is also consistently observed at the transcriptomic level, across independent studies. The enrichment of genes and pathways associated with innate immunity and damage repair-associated pathways supports the model of erythroid danger-associated molecular patterns (DAMPs) as key mediators of the pathogenesis of SCD. Our study also generated a novel database of candidate genes, pathways and transcription factors not previously associated with the pathogenesis of SCD that warrant further investigation in models and patients of SCD.

Optimizing hydroxyurea therapy for sickle cell anemia

Hydroxyurea has proven efficacy in numerous clinical trials as a disease-modifying treatment for patients with sickle cell anemia (SCA) but is currently under-used in clinical practice. To improve the effectiveness of hydroxyurea therapy, efforts should be directed toward broadening the clinical treatment indications, optimizing the daily dosage, and emphasizing the benefits of early and extended treatment. Here, various issues related to hydroxyurea treatment are discussed, focusing on both published evidence and clinical experience. Specific guidance is provided regarding important but potentially unfamiliar aspects of hydroxyurea treatment for SCA, such as escalating to maximum tolerated dose, treating in the setting of cerebrovascular disease, switching from chronic transfusions to hydroxyurea, and using serial phlebotomy to alleviate iron overload. Future research directions to optimize hydroxyurea therapy are also discussed, including personalized dosing based on pharmacokinetic modeling, prediction of fetal hemoglobin responses based on pharmacogenomics, and the risks and benefits of hydroxyurea for non-SCA genotypes and during pregnancy/lactation. Another critical initiative is the introduction of hydroxyurea safely and effectively into global regions that have a high disease burden of SCA but limited resources, such as sub-Saharan Africa, the Caribbean, and India. Final considerations emphasize the long-term goal of optimizing hydroxyurea therapy, which is to help treatment become accepted as standard of care for all patients with SCA.

Optimizing hydroxyurea therapy for sickle cell anemia

Hydroxyurea has proven efficacy in numerous clinical trials as a disease-modifying treatment for patients with sickle cell anemia (SCA) but is currently under-used in clinical practice. To improve the effectiveness of hydroxyurea therapy, efforts should be directed toward broadening the clinical treatment indications, optimizing the daily dosage, and emphasizing the benefits of early and extended treatment. Here, various issues related to hydroxyurea treatment are discussed, focusing on both published evidence and clinical experience. Specific guidance is provided regarding important but potentially unfamiliar aspects of hydroxyurea treatment for SCA, such as escalating to maximum tolerated dose, treating in the setting of cerebrovascular disease, switching from chronic transfusions to hydroxyurea, and using serial phlebotomy to alleviate iron overload. Future research directions to optimize hydroxyurea therapy are also discussed, including personalized dosing based on pharmacokinetic modeling, prediction of fetal hemoglobin responses based on pharmacogenomics, and the risks and benefits of hydroxyurea for non-SCA genotypes and during pregnancy/lactation. Another critical initiative is the introduction of hydroxyurea safely and effectively into global regions that have a high disease burden of SCA but limited resources, such as sub-Saharan Africa, the Caribbean, and India. Final considerations emphasize the long-term goal of optimizing hydroxyurea therapy, which is to help treatment become accepted as standard of care for all patients with SCA.

Observed and expected frequencies of structural hemoglobin variants in newborn screening surveys in Africa and the Middle East: deviations from Hardy-Weinberg equilibrium

PURPOSE

Our objective was to compare observed and expected genotype proportions from newborn screening surveys of structural hemoglobin variants.

METHODS

We conducted a systematic review of newborn screening surveys of hemoglobins S and C in Africa and the Middle East. We compared observed frequencies to those expected assuming Hardy-Weinberg equilibrium (HWE). Significant deviations were identified by an exact test. The fixation index FIS was calculated to assess excess homozygosity. We compared newborn estimates corrected and uncorrected for HWE deviations using demographic data.

RESULTS

Sixty samples reported genotype counts for hemoglobin variants in Africa and the Middle East. Observed and expected counts matched in 27%. The observed number of sickle cell anemia (SCA) individuals was higher than expected in 42 samples, reaching significance (P < 0.05) in 24. High FIS values were common across the study regions. The estimated total number of newborns with SCA, corrected based on FIS, was 33,261 annual births instead of 24,958 for the 38 samples across sub-Saharan Africa and 1,109 annual births instead of 578 for 12 samples from the Middle East.

CONCLUSION

Differences between observed and expected genotype frequencies are common in surveys of hemoglobin variants in the study regions. Further research is required to identify and quantify factors responsible for such deviations. Estimates based on HWE might substantially underestimate the annual number of SCA-affected newborns (up to one-third in sub-Saharan Africa and one-half in the Middle East).

High rate of sickle cell anaemia in Sub-Saharan Africa underlines the need to screen all children with severe anaemia for the disease

AIM

Neonatal screening for sickle cell anaemia is not common practice in the Democratic Republic of Congo, and we determined the prevalence in children with unknown electrophoresis of haemoglobin and anaemia.

METHODS

A cross-sectional study was conducted in four hospitals in the country's capital Kinshasa.

RESULTS

We screened 807 patients with anaemia (Hb < 6 g/dL) for sickle cell disease. The overall mean age at presentation was 42.7 months ± 29.7 months, and most patients (76.3%) were less than five years of age, with a peak incidence at seven to 36 months of age (45%). The median age at the first transfusion was 29 months (range 4-159 months). Of these 807 children, 36 (4.5%) were homozygous for haemoglobin S disease and 45 (5.6%) were heterozygotes. The proportion of patients with homozygous sickle cell anaemia was slightly higher in children with a medical history of hand foot syndrome, in children who had received more than three transfusions and in children up to 36 months of age at their first transfusion.

CONCLUSION

The high prevalence of sickle cell anaemia in children in Sub-Saharan Africa underlines the need for neonatal screening or, if that is not possible, screening of all children with severe anaemia to identify patients with the disease and provide early management.

A Cost-Effectiveness Analysis of a Pilot Neonatal Screening Program for Sickle Cell Anemia in the Republic of Angola

OBJECTIVE

To assess the cost-effectiveness of a pilot newborn screening (NBS) and treatment program for sickle cell anemia (SCA) in Luanda, Angola.

STUDY DESIGN

In July 2011, a pilot NBS and treatment program was implemented in Luanda, Angola. Infants identified with SCA were enrolled in a specialized SCA clinic in which they received preventive care and sickle cell education. In this analysis, the World Health Organization (WHO) and generalized cost-effectiveness analysis methods were used to estimate gross intervention costs of the NBS and treatment program. To determine healthy life-years (HLYs) gained by screening and treatment, we assumed NBS reduced mortality to that of the Angolan population during the first 5 years based upon WHO and Global Burden of Diseases Study 2010 estimates, but provided no significant survival benefit for children who survive through age 5 years. A secondary sensitivity analysis with more conservative estimates of mortality benefits also was performed. The costs of downstream medical costs, including acute care, were not included.

RESULTS

Based upon the costs of screening 36,453 infants and treating the 236 infants with SCA followed after NBS in the pilot project, NBS and treatment program is projected to result in the gain of 452-1105 HLYs, depending upon the discounting rate and survival assumptions used. The corresponding estimated cost per HLY gained is $1380-$3565, less than the gross domestic product per capita in Angola.

CONCLUSIONS

These data demonstrate that NBS and treatment for SCA appear to be highly cost-effective across all scenarios for Angola by the WHO criteria.

Artesunate-amodiaquine versus artemether-lumefantrine for the treatment of acute uncomplicated malaria in Congolese children under 10 years old living in a suburban area: a randomized study

BACKGROUND

The Republic of Congo adopted a new anti-malarial treatment policy in 2006, with artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) as the first- and second-line anti-malarial drugs, respectively. Only three clinical studies had been conducted before the policy change. A randomized study on these two artemisinin-based combinations was conducted, and the effect that sickle cell trait may have on treatment outcomes was evaluated in children under 10 years old followed during 12 months in Brazzaville in 2010-2011.

METHODS

A cohort of 330 children under 10 years of age living in a suburban area in the south of Brazzaville were passively followed for registration of malaria episodes. Uncomplicated Plasmodium falciparum episodes were randomly treated with co-formulated ASAQ (Coarsucam(®)) or AL (Coartem(®)). Patients were followed according to the 2009 World Health Organization protocol for the evaluation of anti-malarial drug efficacy. Plasmodium falciparum recrudescent isolates were compared to pre-treatment isolates by polymerase chain reaction (PCR) to distinguish between re-infection and recrudescence. PCR-uncorrected and PCR-corrected responses to treatment were determined using per protocol analysis. Haemoglobin type (AA, AS, SS) was determined by PCR.

RESULTS

Of 282 clinical malaria episodes registered during 1-year follow-up period, 262 children with uncomplicated malaria were treated with ASAQ (129 patients) or AL (133 patients). The PCR-corrected efficacy, expressed as the percentage of adequate clinical and parasitological response, was 97.0 % for ASAQ and 96.4 % for AL. Among ASAQ-treated patients, 112 (86.8 %) carried AA genotype and 17 (13.2 %) were AS carriers. The PCR-corrected efficacy was 96.4 % for AA-carriers and 100 % for AS-carriers treated with ASAQ [relative risk (RR) = 0.96; 95 % confidence interval, 0.93-1.00, p = 0.5]. Among 133 AL-treated children, 109 (82 %) carried AA, and 24 (18 %) AS genotypes. The PCR-corrected efficacy was 96.7 % among AA-carriers and 95.2 % among AS-carriers [RR = 1.01 (0.92-1.12), p = 0.6]. Nausea, jaundice, headache, dizziness, vomiting, pruritus, abdominal pain, and diarrhoea were registered as adverse events in both groups. ASAQ was associated with significantly more frequent adverse events (P < 0.05).

CONCLUSION

This first randomized study in Brazzaville confirmed the excellent efficacy of these co-formulated anti-malarial drugs in children. Sickle cell genotype did not influence the treatment efficacy of artemisinin-based combination therapy.

An accurate and affordable test for the rapid diagnosis of sickle cell disease could revolutionize the outlook for affected children born in resource-limited settings

Each year, at least 280,000 children are born with sickle cell disease (SCD) in resource-limited settings. For cost, logistic and political reasons, the availability of SCD testing is limited in such settings and consequently 50-90 % of affected children die undiagnosed before their fifth birthday. The recent development of a point of care method for the diagnosis of SCD - the Sickle SCAN™ device - could afford such children the prompt access to appropriate services that has transformed the outlook for affected children in resource-rich areas. In research published in BMC Medicine, Kanter and colleagues describe a small but carefully conducted study involving 208 children and adults, in which they found that by using Sickle SCAN™ it was possible to diagnose the common forms of SCD with 99 % sensitivity and 99 % specificity, in under 5 minutes. If repeatable both in newborn babies and under real-life conditions, and if marketed at an affordable price, Sickle SCAN™ could revolutionize the survival prospects for children born with SCD in resource-limited areas.Please see related article: http://dx.doi.org/10.1186/s12916-015-0473-6.

Absolute Reticulocyte Count Acts as a Surrogate for Fetal Hemoglobin in Infants and Children with Sickle Cell Anemia

Hemoglobin switching is largely complete in humans by six months of age. Among infants with sickle cell anemia (HbSS, SCA), reticulocytosis begins early in life as fetal hemoglobin (HbF) is replaced by sickle hemoglobin (HbS). The objective of this study was to determine if absolute reticulocyte count (ARC) is related to HbF levels in a cohort of pediatric SCA patients. A convenience sample of 106 children with SCA between the ages of 1 month and 20 years who were not receiving hydroxyurea or monthly blood transfusions were enrolled in this observational study. Hematologic data, including ARC and HbF levels, were measured at steady state. F-cells were enumerated by flow cytometry. Initial studies compared infants with ARC greater than or equal to 200 K/μL (ARC ≥ 200) based upon the previously reported utility of this threshold as a predictive marker for SCA severity. Mean HbF and F-cell levels were significantly lower in the ARC ≥ 200 group when compared to the ARC < 200 group. Both HbF and F-cell percentages were negatively correlated to ARC in infants and in children between the ages of 1 and 9 years. However, the inverse relationship was lost after the age of 10 years. Overall, decreased expression and distribution of HbF during childhood SCA is well-correlated with increased reticulocyte production and release into the peripheral blood. As such, these data further support the clinical use of reticulocyte enumeration as a disease severity biomarker for childhood sickle cell anemia.

Hemoglobin switching's surprise: the versatile transcription factor BCL11A is a master repressor of fetal hemoglobin

The major disorders of β-globin, sickle cell disease and β-thalassemia, may be ameliorated by expression of the fetal gene paralog γ-globin. Uncertainty regarding the mechanisms repressing fetal hemoglobin in the adult stage has served as a puzzle of developmental gene regulation as well as a barrier to rational therapeutic design. Recent genome-wide association studies implicated the zinc-finger transcriptional repressor BCL11A in fetal hemoglobin regulation. Extensive genetic analyses have validated BCL11A as a potent repressor of fetal hemoglobin level. Studies of BCL11A exemplify how contextual gene regulation may often be the substrate for trait-associated common genetic variation. These discoveries have suggested novel rational approaches for the β-hemoglobin disorders including therapeutic genome editing.

Hydroxyurea therapy for sickle cell anemia

INTRODUCTION

Sickle cell anemia (SCA) is a severe, inherited hemoglobin disorder affecting 100,000 persons in the US and millions worldwide. Hydroxyurea, a once daily oral medication, has emerged as the primary disease-modifying therapy for SCA. The accumulated body of evidence over 30 years demonstrates that hydroxyurea is a safe and effective therapy for SCA, but hydroxyurea remains underutilized for a variety of reasons.

AREAS COVERED

In this review, we summarize the available evidence regarding the pharmacology, clinical, and laboratory benefits, and safety of hydroxyurea therapy for the treatment of SCA. The purpose of this review is to provide the reader a comprehensive understanding of hydroxyurea and to reinforce the fact that hydroxyurea is a safe and effective medication for the treatment of SCA.

EXPERT OPINION

In our opinion, hydroxyurea therapy should be considered standard-of-care for SCA, representing an essential component of patient management. Early initiation and broader use of hydroxyurea will alter the natural history of SCA, so affected children can live longer and healthier lives. In addition, hydroxyurea use should be extended to low-resource settings such as sub-Saharan Africa, where the burden of SCA and the need for hydroxyurea is arguably the greatest.

Environmental determinants of severity in sickle cell disease

Sickle cell disease causes acute and chronic illness, and median life expectancy is reduced by at least 30 years in all countries, with greater reductions in low-income countries. There is a wide spectrum of severity, with some patients having no symptoms and others suffering frequent, life-changing complications. Much of this variability is unexplained, despite increasingly sophisticated genetic studies. Environmental factors, including climate, air quality, socio-economics, exercise and infection, are likely to be important, as demonstrated by the stark differences in outcomes between patients in Africa and USA/Europe. The effects of weather vary with geography, although most studies show that exposure to cold or wind increases hospital attendance with acute pain. Most of the different air pollutants are closely intercorrelated, and increasing overall levels seem to correlate with increased hospital attendance, although higher concentrations of atmospheric carbon monoxide may offer some benefit for patients with sickle cell disease. Exercise causes some adverse physiological changes, although this may be off-set by improvements in cardiovascular health. Most sickle cell disease patients live in low-income countries and socioeconomic factors are undoubtedly important, but little studied beyond documenting that sickle cell disease is associated with decreases in some measures of social status. Infections cause many of the differences in outcomes seen across the world, but again these effects are relatively poorly understood. All the above factors are likely to account for much of the pathology and variability of sickle cell disease, and large prospective studies are needed to understand these effects better.

Impact of a Comprehensive Sickle Cell Center on Early Childhood Mortality in a Developing Country: The Jamaican Experience

OBJECTIVE

To compare mortality in children <5 years of age with sickle cell disease (SCD) in Jamaica, a resource-limited country, diagnosed by newborn screening and managed in a comprehensive care facility, to that of the general population.

STUDY DESIGN

The study was carried out at the Sickle Cell Unit in Kingston, Jamaica. We determined the status (dead/alive) at age 5 years in a cohort of 548 children with SCD diagnosed by newborn screening and managed at the Sickle Cell Unit during the period November 1995 to December 2009. The standardized mortality ratio was calculated using World Health Organization life tables for reference mortality.

RESULTS

Eight deaths (1.5%) occurred in children <5 years of age during the study period. The mean age at death was 2.0 ± 1.5 years. The overall mortality incidence in children <5 years of age was 3.1 (95% CI 1.6, 6.2) per 1000 person-years with a standardized mortality ratio of 0.52 (95% CI 0.3, 1.0).

CONCLUSIONS

Mortality in children <5 years of age with SCD diagnosed at birth and managed at a comprehensive care clinic in Jamaica is equivalent to that of the general population. Children with SCD, a highly vulnerable population, can be effectively managed, even in resource-limited environments.

Impairment of neutrophil oxidative burst in children with sickle cell disease is associated with heme oxygenase-1

Sickle cell disease is a risk factor for invasive bacterial infections, and splenic dysfunction is believed to be the main underlying cause. We have previously shown that the liberation of heme in acute hemolysis can induce heme oxygenase-1 during granulopoiesis, impairing the ability of developing neutrophils to mount a bactericidal oxidative burst, and increasing susceptibility to bacterial infection. We hypothesized that this may also occur with the chronic hemolysis of sickle cell disease, potentially contributing to susceptibility to infections. We found that neutrophil oxidative burst activity was significantly lower in treatment-naïve children with sickle cell disease compared to age-, gender- and ethnicity-matched controls, whilst degranulation was similar. The defect in neutrophil oxidative burst was quantitatively related to both systemic heme oxygenase-1 activity (assessed by carboxyhemoglobin concentration) and neutrophil mobilization. A distinct population of heme oxygenase-1-expressing cells was present in the bone marrow of children with sickle cell disease, but not in healthy children, with a surface marker profile consistent with neutrophil progenitors (CD49d(Hi) CD24(Lo) CD15(Int) CD16(Int) CD11b(+/-)). Incubation of promyelocytic HL-60 cells with the heme oxygenase-1 substrate and inducer, hemin, demonstrated that heme oxygenase-1 induction during neutrophilic differentiation could reduce oxidative burst capacity. These findings indicate that impairment of neutrophil oxidative burst activity in sickle cell disease is associated with hemolysis and heme oxygenase-1 expression. Neutrophil dysfunction might contribute to risk of infection in sickle cell disease, and measurement of neutrophil oxidative burst might be used to identify patients at greatest risk of infection, who might benefit from enhanced prophylaxis.

Genomic approaches to identifying targets for treating β hemoglobinopathies

Sickle cell disease and β thalassemia are common severe diseases with little effective pathophysiologically-based treatment. Their phenotypic heterogeneity prompted genomic approaches to identify modifiers that ultimately might be exploited therapeutically. Fetal hemoglobin (HbF) is the major modulator of the phenotype of the β hemoglobinopathies. HbF inhibits deoxyHbS polymerization and in β thalassemia compensates for the reduction of HbA. The major success of genomics has been a better understanding the genetic regulation of HbF by identifying the major quantitative trait loci for this trait. If the targets identified can lead to means of increasing HbF to therapeutic levels in sufficient numbers of sickle or β-thalassemia erythrocytes, the pathophysiology of these diseases would be reversed. The availability of new target loci, high-throughput drug screening, and recent advances in genome editing provide the opportunity for new approaches to therapeutically increasing HbF production.

Sickle cell in Latin America and the United States [corrected]

Latin Americans are an underappreciated population affected by sickle cell disease (SCD). Sickle trait and SCD exist throughout Latin America and U.S. Latino communities. We describe the epidemiology and genetic heterogeneity of SCD among Latin Americans, and fetal hemoglobin expression. National population-based newborn screening for SCD is limited to Brazil, Costa Rica, and the U.S. Available and extrapolated data suggest that over 6,000 annual births and 100,000-150,000 Latin Americans are affected by SCD. This comprehensive review highlights the substantial numbers and population distribution of SCD and sickle trait in Latin America, and where national newborn screening programs for SCD exist.

Red blood cell storage duration is not associated with clinical outcomes for acute chest syndrome in children with sickle cell disease

BACKGROUND

Providers commonly transfuse sickle cell disease (SCD) patients with fresh red blood cells (RBCs) as treatment for acute chest syndrome (ACS). The objective of this study was to determine if there is an association between the storage duration of RBCs and length of hospitalization and oxygen requirement after transfusion in pediatric SCD patients with ACS.

STUDY DESIGN AND METHODS

This is a retrospective cohort study of pediatric SCD patients with ACS treated with a simple RBC transfusion over 8.5 years at a single institution. Multivariate generalized estimation equation analysis was used to identify associations between storage duration of RBCs and outcome measures.

RESULTS

A total of 234 ACS episodes in 131 subjects were included. The median storage duration of the oldest unit of transfused RBCs was 17 days (interquartile range, 11-26). The majority of ACS episodes, 77.4%, were treated with 1 unit of transfused RBCs; 20.9% received 2 units; and 1.7% received 3 or more units of RBCs. There was no association between the storage duration of the oldest unit of transfused RBCs and either duration of hospitalization or supplemental oxygen requirement after transfusion in multivariate analyses.

CONCLUSION

This retrospective study is one of the first to investigate the role of the storage lesion in children with SCD and does not support the preferential transfusion of fresh RBCs for ACS. Ultimately, a randomized controlled trial is necessary to determine whether the storage age of RBCs affects outcomes for patients with SCD and ACS.

How we prevent and manage infection in sickle cell disease

Sickle cell disease (SCD) affects approximately 100,000 people in the US, 12,500 in the UK, and millions worldwide. SCD is typified by painful vaso-occlusive episodes, haemolytic anaemia and organ damage. A secondary complication is infection, which can be bacterial, fungal or viral. Universal newborn screening, routine use of penicillin prophylaxis, availability of conjugated vaccines against S. pneumoniae and comprehensive care programmes instituted during the past few decades in industrialized countries have dramatically reduced childhood mortality and improved life expectancy. Yet patients with SCD remain at increased risk of infection. Unfortunately, the treatment of most bacterial infections that are common in SCD is not based on the results of randomized controlled clinical trials. In their absence, treatment decisions are based on consensus guidelines, clinical experience or adapting treatment applied in other diseases. This leads to wide variation in treatment among institutions and even between treating physicians in a single institution. Prevention of infection, when possible, is most important and we focus on prevention through targeted prophylaxis and vaccination. We will share our management strategies for managing the more common infections in SCD and provide the rationale for our recommendations.

Negative Epistasis between Sickle and Foetal Haemoglobin Suggests a Reduction in Protection against Malaria

BACKGROUND

Haemoglobin variants, Sickle (HbS) and foetal (HbF) have been associated with malaria protection. This study explores epistatic interactions between HbS and HbF on malaria infection.

METHODS

The study was conducted between March 2004 and December 2013 within the sickle cell disease (SCD) programme at Muhimbili National Hospital, Tanzania. SCD status was categorized into HbAA, HbAS and HbSS using hemoglobin electrophoresis and High Performance Liquid Chromatography (HPLC). HbF levels were determined by HPLC. Malaria was diagnosed using rapid diagnostic test and/or blood film. Logistic regression and generalized estimating equations models were used to evaluate associations between SCD status, HbF and malaria.

FINDINGS

2,049 individuals with age range 0-70 years, HbAA 311(15.2%), HbAS 241(11.8%) and HbSS 1,497(73.1%) were analysed. At enrolment, malaria prevalence was significantly higher in HbAA 13.2% compared to HbAS 1.24% and HbSS 1.34% (p<0.001). Mean HbF was lower in those with malaria compared to those without malaria in HbAA (0.43% vs 0.82%) but was the reverse in HbSS (8.10% vs 5.59%). An increase in HbF was associated with a decrease in risk of malaria OR=0.50 (95%CI: 0.28, 0.90; p=0.021) in HbAA, whereas for HbSS the risk of malaria increased OR=2.94 (1.44, 5.98; p=0.003). A similar pattern was seen during multiple visits; HbAA OR=0.52 (0.34, 0.80; p=0.003) vs HbSS OR=2.01 (1.27, 3.23; p=0.003).

CONCLUSION

Higher prevalence of malaria in HbAA compared to HbAS and HbSS confirmed the protective effect of HbS. Lower prevalence of malaria in HbAA with high HbF supports a protective effect of HbF. However, in HbSS, the higher prevalence of malaria with high levels of HbF suggests loss of malaria protection. This is the first epidemiological study to suggest a negative epistasis between HbF and HbS on malaria.

Correlation between the Lactate Dehydrogenase Levels with Laboratory Variables in the Clinical Severity of Sickle Cell Anemia in Congolese Patients

Background

Sickle cell anemia is an inflammatory disease and is characterized by chronic hemolysis. We sought to evaluate the association of lactate dehydrogenase levels with specific clinical phenotypes and laboratory variables in patients with sickle cell anemia.

Methods

The present cross-sectional study was conducted in Sickle Cell Centre of Yolo in Kinshasa, the Democratic Republic of Congo. Two hundred and eleven patients with Sickle Cell Anemia in steady state were recruited. Seventy-four participants with normal Hb (Hb-AA) were selected as a control group.

Results

The average rates of hemoglobin, hematocrit, and red blood cells tended to be significantly lower in subjects with Hb-SS (p<0.001). The average rates of white blood cells, platelets, reticulocytes and serum LDH were significantly higher in subjects with Hb-SS (p<0.001). The average rates of Hb, HbF, hematocrit and red blood cells of Hb-SS patients with asymptomatic clinical phenotype were significantly higher than those of the two other phenotypes. However, the average rates of white blood cells, platelets, reticulocytes, and LDH of Hb-SS patients with the severe clinical phenotype are higher than those of two other clinical phenotypes. Significant correlations were observed between Hb and white blood cell in severe clinical phenotype (r3 = -0.37 *) between Hb and red blood cells in the three phenotypes (r1 = 0.69 * r2 * = 0.69, r3 = 0.83 *), and finally between Hb and reticulocytes in the asymptomatic clinical phenotype and severe clinical phenotype (r1 = -0.50 * r3 = 0.45 *). A significant increase in LDH was observed in patients with leg ulcer, cholelithiasis and aseptic necrosis of the femoral head.

Conclusion

The increase in serum LDH is accompanied by changes in hematological parameters. In our midst, serum LDH may be considered as an indicator of the severity of the disease.

Malaria continues to select for sickle cell trait in Central Africa

Sickle cell disease (SCD) is a genetic disorder that poses a serious health threat in tropical Africa, which the World Health Organization has declared a public health priority. Its persistence in human populations has been attributed to the resistance it provides to Plasmodium falciparum malaria in its heterozygous state, called sickle cell trait (SCT). Because of migration, SCT is becoming common outside tropical countries: It is now the most important genetic disorder in France, affecting one birth for every 2,400, and one of the most common in the United States. We assess the strength of the association between SCT and malaria, using current data for both SCT and malaria infections. A total of 3,959 blood samples from 195 villages distributed over the entire Republic of Gabon were analyzed. Hemoglobin variants were identified by using HPLCy (HPLC). Infections by three species of Plasmodium were detected by PCR followed by sequencing of a 201-bp fragment of cytochrome b. An increase of 10% in P. falciparum malaria prevalence is associated with an increase by 4.3% of SCT carriers. An increase of 10 y of age is associated with an increase by 5.5% of SCT carriers. Sex is not associated with SCT. These strong associations show that malaria remains a selective factor in current human populations, despite the progress of medicine and the actions undertaken to fight this disease. Our results provide evidence that evolution is still present in humans, although this is sometimes questioned by scientific, political, or religious personalities.

Knowledge and awareness of personal sickle cell genotype among parents of children with sickle cell disease in southeast Nigeria

Sickle cell trait (SCT; HbAS), the heterozygous state for the sickle cell allele of the beta globin gene, is carried by as many as 100 million individuals worldwide. Nigeria has the highest prevalence of SCT, impacting an estimated 25 % of adult population. This study was designed to assess timing of awareness, knowledge of SCT status and preferred method of education among parents of children with sickle cell disease (SCD). We conducted a cross-sectional survey of parents of children with SCD from June 2013-March 2014. Participants completed a 20-item questionnaire to assess (1) awareness of personal sickle cell genotype, (2) timing of awareness of personal sickle cell genotype, and (3) knowledge of SCT. One hundred and fifty-five participants completed the survey. Seventy-eight percent were females, and 87 % (135/155) were aware of their own sickle cell genotype. Timing of awareness varied as follows: following birth of a child with sickle cell disease (45 %); during marriage (21.5 %); school admission (9.6 %); during pregnancy (9.6 %); and other times (14 %). Approximately 35.5 % of participants thought that sickle cell trait was a mild form of sickle cell disease. Radio (43.9 %), informational community meetings (27.7 %), and television (21.9 %) were identified by participants as the most effective method of increasing sickle cell trait awareness. Innovative approaches are needed to increase the proportion of individuals who are aware of their own sickle cell genotype prior to having a child with sickle cell anemia in line with the Healthy People 2020 objective.