Identifying Genetic and Biological Determinants of Race-Ethnic Disparities in Stroke in the United States.

In the United States, causes of racial differences in stroke and its risk factors remain only partly understood, and there is a long-standing disparity in stroke incidence and mortality impacting Black Americans. Only half of the excess risk of stroke in the United States Black population is explained by traditional risk factors, suggesting potential effects of other factors including genetic and biological characteristics. Here, we nonsystematically reviewed candidate laboratory biomarkers for stroke and their relationships to racial disparities in stroke. Current evidence indicates that IL-6 (interleukin-6), a proinflammatory cytokine, mediates racial disparities in stroke through its association with traditional risk factors. Only one reviewed biomarker, Lp(a) (lipoprotein[a]), is a race-specific risk factor for stroke. Lp(a) is highly genetically determined and levels are substantially higher in Black than White people; clinical and pharmaceutical ramifications for stroke prevention remain uncertain. Other studied stroke risk biomarkers did not explain racial differences in stroke. More research on Lp(a) and other biological and genetic risk factors is needed to understand and mitigate racial disparities in stroke.

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.

Sickle Cell Trait from a Metabolic, Renal, and Vascular Perspective: Linking History, Knowledge, and Health.

Sickle cell trait (SCT) is at the intersection of genetics, social policy, and medicine. SCT occurs in three-hundred million people worldwide and in approximately 8 % of African-Americans. There has been great debate about the influence of SCT on health. Yet data exist, albeit controversial, which suggest that SCT is associated with metabolic derangements that can lead to sudden death after vigorous physical activity, renal dysfunction, thromboembolic events, and stroke. In addition, it has even been postulated that SCT might enhance the vascular complications of diabetes. This review focuses on (a) the scientific breakthroughs that led to the discovery of hemoglobin S, sickle cell disease, and SCT, (b) the history of screening programs in the United States, (c) the incidence and etiology of exercise-related sudden death in military personnel and athletes with SCT, and (d) the data examining the potential chronic disease consequences of SCT from a metabolic, renal, and vascular perspective.

Obstetrician-gynecologists' knowledge of sickle cell disease screening and management.

BACKGROUND: Although obstetrician/gynecologists (OB/GYNs) play an important role in sickle cell disease (SCD) screening and patient care, there is little information on knowledge of SCD or sickle cell trait (SCT) or related practices in this provider group. Our objective was to assess SCD screening and prenatal management practices among OB/GYNs. METHODS: Twelve hundred Fellows and Junior Fellows of the American College of Obstetricians and Gynecologists (the College)a were invited to complete a mailed survey, of which half (n = 600) belonged to the Collaborative Ambulatory Research Network.b Participants answered questions regarding appropriate target patient groups for prenatal SCD screening, folic acid requirements, practice behaviors and adequacy of their medical school and residency training. RESULTS: A total of 338 CARN members (56.3%) and 165 non-CARN members (27.5%) returned a survey. Of the 503 responders, 382 provided obstetric services and were included in the analyses. Forty percent of these respondents (n = 153) reported seeing at least 1 patient with SCD in the last year. Of these, 97.4% reported regularly screening people of African descent for SCD or SCT, whereas 52.9% reported regularly screening people of Mediterranean descent and 30.1% reported regularly screening people of Asian descent. Only 56.2% knew the correct recommended daily dose of folic acid for pregnant women with SCD. The proportion of respondents that rated training on SCD screening, assessment and treatment as barely adequate or inadequate ranged from 19.7% to 39.3%. CONCLUSIONS: The practice of many OB/GYNs who care for patients with SCD are not consistent with the College Practice Guidelines on the screening of certain target groups and on folic acid supplementation. There may be an opportunity to improve this knowledge gap through enhanced medical education.

Sickle trait in African-American hemodialysis patients and higher erythropoiesis-stimulating agent dose.

African Americans require higher doses of erythropoiesis-stimulating agents (ESAs) during dialysis to manage anemia, but the influence of sickle cell trait and other hemoglobinopathy traits on anemia in dialysis patients has not been adequately evaluated. We performed a cross-sectional study of a large cohort of adult African-American hemodialysis patients in the United States to determine the prevalence of hemoglobinopathy traits and quantify their influence on ESA dosing. Laboratory and clinical data were obtained over 6 months in 2011. Among 5319 African-American patients, 542 (10.2%) patients had sickle cell trait, and 129 (2.4%) patients had hemoglobin C trait; no other hemoglobinopathy traits were present. Sickle cell trait was more common in this cohort than the general African-American population (10.2% versus 6.5%-8.7%, respectively, P<0.05). Among 5002 patients (10.3% sickle cell trait and 2.4% hemoglobin C trait) receiving ESAs, demographic and clinical variables were similar across groups, with achieved hemoglobin levels being nearly identical. Patients with hemoglobinopathy traits received higher median doses of ESA than patients with normal hemoglobin (4737.4 versus 4364.1 units/treatment, respectively, P=0.02). In multivariable analyses, hemoglobinopathy traits associated with 13.2% more ESA per treatment (P=0.001). Within subgroups, sickle cell trait patients received 13.2% (P=0.003) higher dose and hemoglobin C trait patients exhibited a similar difference (12.9%, P=0.12). Sensitivity analyses using weight-based dosing definitions and separate logistic regression models showed comparable associations. Our findings suggest that the presence of sickle cell trait and hemoglobin C trait may explain, at least in part, prior observations of greater ESA doses administered to African-American dialysis patients relative to Caucasian patients.

Haplotipos del gen de la globina beta en portadores de hemoglobina S en Colombia / Beta globin haplotypes in hemoglobin S carriers in Colombia

Introducción. La mutación de la hemoglobina S (HbS) va acompañada por otras mutaciones en la región del cromosoma 11, conocida como conjunto de la globina beta(beta globin cluster). El patrón de combinación de estos polimorfismos da lugar a los haplotipos que se heredan junto con la mutación de la hemoglobina S, se denominan haplotipos de la mutación bs y revisten gran importancia epidemiológica y clínica. Objetivo. Determinar la frecuencia de los principales haplotipos asociados al gen HBB en pacientes colombianos heterocigotos para hemoglobina S. Materiales y métodos. En la Clínica Colsanitas se han estudiado a la fecha 1.200 muestras de sangre periférica de niños en busca de hemoglobinopatías, y se ha encontrado el rasgo falciforme como la hemoglobinopatía más frecuente. Se determinaron los haplotipos del gen HBB que presentaron la mutación beta-S en 33 niños con patrón electroforético de hemoglobina AS, mediante reacción en cadena de la polimerasa (PCR) y enzimas de restricción. Se determinaron el patrón electroforético de la hemoglobina, el nivel de hemoglobina fetal y los parámetros hematológicos de cada individuo. Resultados. Los haplotipos de la hemoglobina S encontrados con mayor frecuencia en la muestra analizada son de origen africano y su orden de aparición fue mayor para el haplotipo Bantú (36,4 %), seguido por Senegal (30,3 %), Benín (21,2 %) y Camerún (12,1 %). La electroforesis de hemoglobina confirmó el fenotipo AS; la dosificación de hemoglobina fetal mostró niveles por debajo de 1 % y los parámetros hematológicos analizados mostraron valores normales en el 100 % de los individuos. Conclusión. Los haplotipos de la HbS encontrados con mayor frecuencia en la muestra estudiada eran de origen africano y su distribución variaba de acuerdo con el lugar de prodedencia del individuo. La mayor frecuencia correspodió al haplotipo Bantú.

Introduction. The hemoglobin S (HbS) mutation is accompanied by other mutations in the region of chromosome 11 known as "beta globin cluster". The pattern of combination of these polymorphisms giving rise to the haplotypes that co-inherit the HbS mutation, are called haplotypes bs, and are of great epidemiological and clinical significance. Objective. The frequencies of major haplotypes associated with S beta-globin gene was determined in Colombian patients heterozygous for hemoglobin S. Materials and methods. As part of the national neonatal screening program at Clínica Colsanitas, located in major cities of Colombia, nearly 1,200 children from different areas of the country were examined for hemoglobinopathies. The sickle cell trait was identified as the most common. S beta-globin gene haplotypes were determined by PCR and restriction enzymes in 33 children with AS hemoglobin electrophoretic patterns (carrier state). In addition, electrophoretic patterns of hemoglobin, fetal hemoglobin levels and hematologic parameters of each individual were identified. Results. The most frequent haplotypes in Colombia were the Bantú haplotype (36.4 %), followed by Senegal (30.3 %), Benin (21.2 %) and Cameroon (12.1 %) haplotypes. Hemoglobin electrophoresis confirmed the AS phenotype in all patients, and fetal hemoglobin levels below 1%. Other hematological parameters were normal in all cases. Conclusion. The HbS haplotypes found more frequently in the sample were of African origin, and their distribution varied according to the place of origin of the individual. The most frequent corresponded to the Bantu haplotype.

[Co-inheritance of autosomal dominant polycystic kidney disease and sickle cell trait in African Americans]. / Co-herencia de poliquistosis renal autosómica dominante y hemoglobina con rasgo falciforme en afroamericanos.

BACKGROUND: Macroscopic haematuria secondary to renal cyst rupture is a frequent complication in autosomal dominant polycystic kidney disease (ADPKD). Sickle-cell disease is an autosomal recessive haemoglobinopathy that involves a qualitative anomaly of haemoglobin due to substitution of valine for the glutamic acid in the sixth position of 3-globin gene on the short arm of chromosome 11. For the full disease to be manifested, this mutation must be present on both inherited alleles. The severity of the disease is proportional to the quantity of haemoglobin S (Hb S) in the red cells; sickle-cell trait (Hb S <50%) and homozygous sickle-cell disease (Hb S >75%). In sickle-cell disease, the abnormal Hb S loses its rheological characteristics and is responsible of the various systemic manifestations including those of the kidney, such as macroscopic haematuria secondary to papilar necrosis. Despite the generally benign nature of the sickle-cell trait, several potentially serious complications have been described. Metabolic or environmental changes such as hypoxia, acidosis, dehydration, hyperosmolality or hyperthermia may transform silent sickle-cell trait into a syndrome resembling sickle-cell disease with vaso-occlusive crisis due to an accumulation of low deformable red blood cells in the microcirculation originating haematuria from papilar necrosis. On the other hand, it has been demonstrated an earlier onset of end-stage renal disease (ESRD), in blacks with ADPKD and sickle-cell trait when compared with blacks with ADPKD without the trait. PATIENTS AND METHODS: We studied 2 african-american families (4 patients) which presented with both ADPKD and sickle-cell trait (Hb S <50%). The diagnosis of sickle-cell trait was confirmed by haemoglobin electrophoresis. The renal volume was measured by magnetic resonance imaging (MRI). RESULTS: The proband subject in family 1 presented frequent haematuria episodes, associated to increase of renal volume, developed very early ESRD and was dialyzed at the age of 39 years. The other 3 patients in family 2 presented different degree of renal function. CONCLUSIONS: The presence of sickle haemoglobin should be determined in african-american and west-african patients with ADPKD because it is an important prognostic factor. Coherence of sickle-cell trait may have influence on ADPKD evolution to ESRD and other complications, such as cystic haemorrhages. MRI can identify intracystic haemorrhage and permit renal volume measure.

Um caso de discriminação genética: o traço falciforme no Brasil / Genetic Discrimination: sickle cell trait in Brazil

Este artigo discute um caso de discriminação genética envolvendo uma atleta brasileira de voleibol identificada como portadora do traço falciforme. O traço falciforme é uma das características genéticas mais prevalentes na população brasileira, mas não é descrito como uma doença genética. O avanço da genética clínica vem provocando uma popularização dos testes genéticos em diferentes contextos de promoção da saúde. Ao criticar o argumento da Confederação Brasileira de Vôlei de que o exame para o traço falciforme seria uma medida de proteção à saúde dos atletas, o objetivo do artigo foi demonstrar como a popularização da informação genética não pode prescindir do aconselhamento genético e de garantias éticas. A análise mostrou que a exclusão da atleta da seleção oficial de vôlei não se justificou por medidas de proteção à saúde, mas por discriminação genética.

This paper analyses a case of genetic discrimination of a Brazilian volleyball athlete. A routine exam identified the sickle cell trait in her blood. The sickle cell trait is one of the most prevalent genetic information in Brazilian population, but it not considered a genetic disease. The advancement of clinical genetic promotes a popularization of genetic tests in different health care initiatives. The aims of this paper are: 1) to criticize the argument supporting the test for sickle cell trait as a health care initiative; 2) to demonstrate how the popularization of genetic information demands genetic counseling and ethical protections. The analysis demonstrates how the athlete exclusion from the official volleyball team is not supported by medicine and is a case of genetic discrimination.

The feasibility of using ethnicity as a primary tool for antenatal selective screening for sickle cell disorders: pointers from the research evidence.

The Department of Health has announced a linked antenatal and neonatal screening programme for haemoglobinopathies by 2004 in a comprehensive national plan for the National Health Service in Britain. In response the National Screening Committee has commenced development work on how such a programme can best be implemented, including investigation of the effectiveness of a question about ethnic origin as a basis for selection. In addition, two recent health technology assessment reports have assessed alternative options for antenatal and neonatal haemoglobinopathy screening programmes in the United Kingdom. Both reports and commentators have emphasised the importance of developing a standardised instrument for collecting ethnicity data and recommended early development of such work. An examination of the evidence base on the use of ethnicity as a primary screening tool reveals substantial variability in practice and in the quality of data collected, with risk group misclassification as high as 20% against a recommended target of under 5.5%. The literature on the conceptual basis and structure of ethnicity questions, method of assignment in data collection, and level of resolution on categorisation is reviewed to identify the most appropriate content and format of a screening question for the haemoglobinopathies. Question options are evaluated, including the use of an extended 2001 Census classification and a 'non-North European' identifier and a candidate question based on 'family origins' is offered for debate. Finally, issues relating to the testing of the efficiency of an ethnicity question and the operationalising of its use for antenatal sickle cell screening are discussed.

Hemoglobinopathies among five major ethnic groups in Karachi, Pakistan.

A brief survey of abnormal hemoglobin variants among the major ethnic groups of Karachi was conducted; 202,600 subjects were studied. Patients with low hemoglobin (Hb), low mean cell volume (MCV) and mean cell hemoglobin (MCH) including anemia, microcytosis, hypochromic hemolysis and target cells, were refered for the identification of hemoglobinopathy by molecular methods. Population screening showed that 60% had iron-deficiency anemia and 40% had hemolytic anemia, of which 20.6% was due to beta-thalassemia major, 13% beta-thalassemia trait, 5.1% sickle cell disease, 0.76% hemoglobin D Punjab (HbD Punjab), 0.32% hemoglobin C (HbC), and 0.22% hereditary persistence of fetal hemoglobin (HPFH).

[Cardiac surgery using cardiopulmonary bypass in a patient with sickle-cell trait].

The sickle-cell gene is most concentrated in West Central Africa, the northeast corner of Saudi Arabia and East Central India. Sickle cell trait is the heterozygous condition for Hb S gene. Thirty to fifty per cent of their hemoglobin is Hb S and the remainder is Hb A. The sickle-cell crisis is induced by hypoxia, hypercarbia, acidosis, low flow condition, and hypothermia, which leads to vasoocclusion. A 39-year-old black man from Burkina Faso located in West Africa with left ventricular rupture was admitted for operation using cardiopulmonary bypass (CPB). He had been diagnosed as sickle-cell trait. The Hb S concentration was 36.2 per cent before operation with hemoglobin electrophoresis. During CPB, the minimum blood temperature was 31 degrees C and an aortic cross-clamp was not done. Total CPB time was 1 hour 31 minutes. Use of vasodilator and hyperventilation was effective. No neurological sequelae were observed.

Screening for sickle-cell trait in the emergency department.

OBJECTIVE: To determine 1) whether young adult black patients in an emergency department (ED) are familiar with sickle-cell anemia and 2) how many of these patients know their own sickle-cell trait status. DESIGN: Black patients in an ED were interviewed. Women aged 18 to 40 years and men aged 18 to 50 were included. Sickle-cell screening was offered to the patients. SETTING: The ED of a large urban university hospital with an annual census of 50,000, approximately 25% of whom are black. PATIENTS: A convenience sample of 147 black patients presenting to the ED with minor medical conditions. INTERVENTIONS: The subjects were interviewed to determine their knowledge base regarding sickle-cell anemia and to determine how many knew their sickle-cell trait status. The subjects were tested for sickle-cell trait. MEASUREMENTS AND MAIN RESULTS: 98% of the patients had heard of sickle-cell anemia and 73% knew that it was a genetic disorder. Only 31% of the patients knew their sickle-cell status. Women were more likely than men to know their status. Approximately half of the patients who had family histories of the trait or the disease knew their own status. Two of the 47 patients (4%) tested had positive sickle-cell screen results. CONCLUSIONS: Most black patients of childbearing age presenting to the ED have heard of sickle-cell anemia and know that it runs in families, but few know their own trait status. Until access to primary care providers is improved, ED physicians who care for patients at risk for sickle-cell trait have an obligation to ask them about prior screening and either screen them or refer them for screening.

Growth and development in white patients with sickle cell diseases.

We have evaluated height, weight, bone age, somatomedin-C levels, and pubertal development in 114 Sicilian patients affected by sickle cell diseases (SCDs). Thirty-one had homozygous sickle hemoglobin (SS), 55 S-beta 0 thalassemia, and 28 S-beta + thalassemia. In both children and adults, the mean height and weight were approximately 1 SD below the normal mean for age. The height was below the normal range only in a few subjects (8 children and 4 adult women). Somatomedin-C levels were within the normal range in most of the patients (37/44 children and 17/22 adults). Bone age revealed a slight delay in skeletal maturation (mean chronological age and bone age were 7.7 +/- 3 and 7.11 +/- 2.9 respectively; p < 0.05). Mean age at menarche was increased compared to normal subjects. Our findings show that Sicilian patients with SCD exhibit a moderate delay of growth and adolescence but attain a final height within the normal range.

Prediction and diagnosis of sickling disorders in neonates.

A pilot scheme for the prediction and detection of sickle cell disease in neonates was set up and the results from its first three years of operation analysed. A total of 153 women booking at the antenatal clinic were found to have haemoglobin S. The protocol required that all partners of the women so identified be screened for abnormal haemoglobins and beta thalassaemia trait, and that the babies of these women should have cord blood electrophoresis performed. In fact this was only achieved in 75 partners (49%) and 91 of 145 infants (63%). Of 10 babies born with sickle cell disease during the study period, nine had mothers known to have haemoglobin S or C, but only four of these mothers' partners had been tested before delivery of the child. This pilot study highlights the problems in establishing effective antenatal screening programmes, especially in ethnic minority groups. The results show that detailed staff training, careful organisation of administrative arrangements, and education of 'at risk' groups should all be undertaken before the launching of major screening initiatives.