scholarly journals Effects of hydroxyurea on hemoglobin F and water content in the red blood cells of dogs and of patients with sickle cell anemia

Blood ◽  
1991 ◽  
Vol 78 (1) ◽  
pp. 212-216 ◽  
Author(s):  
EP Orringer ◽  
DS Blythe ◽  
AE Johnson ◽  
G Jr Phillips ◽  
GJ Dover ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Water Content ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Fetal Hemoglobin ◽  
Hemoglobin Concentration ◽  
Mean Corpuscular Hemoglobin ◽  
Cell Disease ◽  
Hemoglobin F ◽  
The Mean

A rationale for clinical trials of hydroxyurea (HU) treatment in sickle cell disease is that the agent increases red blood cell (RBC) fetal hemoglobin content. However, an additional effect of HU is to raise the mean corpuscular volume (MCV). To investigate the action of HU in a species that makes no electrophoretically distinguishable fetal hemoglobin, we treated dogs with the drug and compared their response to that of five patients with sickle cell anemia. Both dogs and patients had an increase in MCV, but the effect of HU treatment on the mean corpuscular hemoglobin concentration (MCHC), density, and water content of the RBCs differed in the two species. The dog RBCs became low in MCHC, high in ion and water content, and low in mean density. Thus, HU can raise MCV and lower MCHC without influencing fetal hemoglobin synthesis. A different pattern was seen in the sickle cell patients during HU treatment. Although the MCV of their RBCs increased, there was no change in MCHC, ion content, or mean density. A notable change in the sickle cell patients' blood was that two subpopulations of cells were nearly eliminated during HU treatment; the hypodense reticulocyte fraction and the hyperdense fraction that contains irreversibly sickled cells. These findings lead us to suggest that trials of HU in sickle cell disease must recognize the possibility that any beneficial effect of this agent might be due not only to an increase in hemoglobin F alone, but perhaps also to the associated increase in MCV or the altered RBC density profile.

scholarly journals Effects of hydroxyurea on hemoglobin F and water content in the red blood cells of dogs and of patients with sickle cell anemia

Blood ◽  
1991 ◽  
Vol 78 (1) ◽  
pp. 212-216 ◽  
Author(s):  
EP Orringer ◽  
DS Blythe ◽  
AE Johnson ◽  
G Jr Phillips ◽  
GJ Dover ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Water Content ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Fetal Hemoglobin ◽  
Hemoglobin Concentration ◽  
Mean Corpuscular Hemoglobin ◽  
Cell Disease ◽  
Hemoglobin F ◽  
The Mean

Abstract A rationale for clinical trials of hydroxyurea (HU) treatment in sickle cell disease is that the agent increases red blood cell (RBC) fetal hemoglobin content. However, an additional effect of HU is to raise the mean corpuscular volume (MCV). To investigate the action of HU in a species that makes no electrophoretically distinguishable fetal hemoglobin, we treated dogs with the drug and compared their response to that of five patients with sickle cell anemia. Both dogs and patients had an increase in MCV, but the effect of HU treatment on the mean corpuscular hemoglobin concentration (MCHC), density, and water content of the RBCs differed in the two species. The dog RBCs became low in MCHC, high in ion and water content, and low in mean density. Thus, HU can raise MCV and lower MCHC without influencing fetal hemoglobin synthesis. A different pattern was seen in the sickle cell patients during HU treatment. Although the MCV of their RBCs increased, there was no change in MCHC, ion content, or mean density. A notable change in the sickle cell patients' blood was that two subpopulations of cells were nearly eliminated during HU treatment; the hypodense reticulocyte fraction and the hyperdense fraction that contains irreversibly sickled cells. These findings lead us to suggest that trials of HU in sickle cell disease must recognize the possibility that any beneficial effect of this agent might be due not only to an increase in hemoglobin F alone, but perhaps also to the associated increase in MCV or the altered RBC density profile.

scholarly journals Relationship of erythropoietin, fetal hemoglobin, and hydroxyurea treatment to tricuspid regurgitation velocity in children with sickle cell disease

Blood ◽  
2009 ◽  
Vol 114 (21) ◽  
pp. 4639-4644 ◽  
Author(s):  
Victor R. Gordeuk ◽  
Andrew Campbell ◽  
Sohail Rana ◽  
Mehdi Nouraie ◽  
Xiaomei Niu ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Tricuspid Regurgitation ◽  
Fetal Hemoglobin ◽  
Hemoglobin Concentration ◽  
Systolic Pulmonary Artery Pressure ◽  
Cell Disease ◽  
Hemoglobin F ◽  
Hydroxyurea Treatment ◽  
Relationship Of

AbstractHydroxyurea and higher hemoglobin F improve the clinical course and survival in sickle cell disease, but their roles in protecting from pulmonary hypertension are not clear. We studied 399 children and adolescents with sickle cell disease at steady state; 38% were being treated with hydroxyurea. Patients on hydroxyurea had higher hemoglobin concentration and lower values for a hemolytic component derived from 4 markers of hemolysis (P ≤ .002) but no difference in tricuspid regurgitation velocity compared with those not receiving hydroxyurea; they also had higher hemoglobin F (P < .001) and erythropoietin (P = .012) levels. Hemoglobin F correlated positively with erythropoietin even after adjustment for hemoglobin concentration (P < .001). Greater hemoglobin F and erythropoietin each independently predicted higher regurgitation velocity in addition to the hemolytic component (P ≤ .023). In conclusion, increase in hemoglobin F in sickle cell disease may be associated with relatively lower tissue oxygen delivery as reflected in higher erythropoietin concentration. Greater levels of erythropoietin or hemoglobin F were independently associated with higher tricuspid regurgitation velocity after adjustment for degree of hemolysis, suggesting an independent relationship of hypoxia with higher systolic pulmonary artery pressure. The hemolysis-lowering and hemoglobin F–augmenting effects of hydroxyurea may exert countervailing influences on pulmonary blood pressure in sickle cell disease.

scholarly journals Analysis of hemoglobin F production in Saudi Arabian families with sickle cell anemia

Blood ◽  
1987 ◽  
Vol 70 (3) ◽  
pp. 716-720 ◽  
Author(s):  
BA Miller ◽  
M Salameh ◽  
M Ahmed ◽  
N Olivieri ◽  
G Antognetti ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Cell Disease ◽  
Erythroid Progenitors ◽  
Hemoglobin F ◽  
Gamma Globin ◽  
Hemoglobin Production

Erythrocytes and progenitor-derived erythroblasts of sickle cell anemia patients from the Eastern Province of Saudi Arabia contain increased fetal hemoglobin and G gamma globin. A distinctive DNA polymorphism haplotype in the beta globin gene cluster (++- +-), tightly coupled to a C----T substitution at position -158 5′ to the cap site of the G gamma globin gene, is strongly associated with sickle cell disease in this region. To determine whether the increased fetal hemoglobin production and/or elevated G gamma globin content are tightly linked to this haplotype, we studied 55 members of five Saudi families in which sickle cell disease is present. The results did not suggest a tight linkage of the haplotype to increased fetal hemoglobin production. On the other hand, several sickle trait family members heterozygous for the haplotype had normal fetal hemoglobin production in culture but elevated G gamma to A gamma ratios in peripheral blood. This observation suggests that in this genetic background increased expression of the G gamma globin gene may occur without a measurable increase in total fetal hemoglobin production. The family studies also clearly demonstrate that increased fetal hemoglobin production by erythroid progenitors is dependent on zygosity for the sickle gene in this population. These findings strongly suggest that other factors, such as the products of genes stimulated by hemolytic stress or other genetic determinants associated with the Saudi beta S chromosome, may interact with the -158 C----T substitution and influence gamma globin gene expression in this population.

Fetal hemoglobin in sickle cell anemia: a glass half full?

Blood ◽  
2014 ◽  
Vol 123 (4) ◽  
pp. 481-485 ◽  
Author(s):  
Martin H. Steinberg ◽  
David H. K. Chui ◽  
George J. Dover ◽  
Paola Sebastiani ◽  
Abdulrahman Alsultan
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Severe Disease ◽  
Fetal Hemoglobin ◽  
Cell Disease ◽  
Sickle Hemoglobin ◽  
F Cells ◽  
The Mean ◽  
Number Of Cells

Abstract Fetal hemoglobin (HbF) modulates the phenotype of sickle cell anemia by inhibiting deoxy sickle hemoglobin (HbS) polymerization. The blood concentration of HbF, or the number of cells with detectable HbF (F-cells), does not measure the amount of HbF/F-cell. Even patients with high HbF can have severe disease because HbF is unevenly distributed among F-cells, and some cells might have insufficient concentrations to inhibit HbS polymerization. With mean HbF levels of 5%, 10%, 20%, and 30%, the distribution of HbF/F-cell can greatly vary, even if the mean is constant. For example, with 20% HbF, as few as 1% and as many as 24% of cells can have polymer-inhibiting, or protective, levels of HbF of ∼10 pg; with lower HbF, few or no protected cells can be present. Only when the total HbF concentration is near 30% is it possible for the number of protected cells to approach 70%. Rather than the total number of F-cells or the concentration of HbF in the hemolysate, HbF/F-cell and the proportion of F-cells that have enough HbF to thwart HbS polymerization is the most critical predictor of the likelihood of severe sickle cell disease.

scholarly journals Analysis of hemoglobin F production in Saudi Arabian families with sickle cell anemia

Blood ◽  
1987 ◽  
Vol 70 (3) ◽  
pp. 716-720 ◽  
Author(s):  
BA Miller ◽  
M Salameh ◽  
M Ahmed ◽  
N Olivieri ◽  
G Antognetti ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Cell Disease ◽  
Erythroid Progenitors ◽  
Hemoglobin F ◽  
Gamma Globin ◽  
Hemoglobin Production

Abstract Erythrocytes and progenitor-derived erythroblasts of sickle cell anemia patients from the Eastern Province of Saudi Arabia contain increased fetal hemoglobin and G gamma globin. A distinctive DNA polymorphism haplotype in the beta globin gene cluster (++- +-), tightly coupled to a C----T substitution at position -158 5′ to the cap site of the G gamma globin gene, is strongly associated with sickle cell disease in this region. To determine whether the increased fetal hemoglobin production and/or elevated G gamma globin content are tightly linked to this haplotype, we studied 55 members of five Saudi families in which sickle cell disease is present. The results did not suggest a tight linkage of the haplotype to increased fetal hemoglobin production. On the other hand, several sickle trait family members heterozygous for the haplotype had normal fetal hemoglobin production in culture but elevated G gamma to A gamma ratios in peripheral blood. This observation suggests that in this genetic background increased expression of the G gamma globin gene may occur without a measurable increase in total fetal hemoglobin production. The family studies also clearly demonstrate that increased fetal hemoglobin production by erythroid progenitors is dependent on zygosity for the sickle gene in this population. These findings strongly suggest that other factors, such as the products of genes stimulated by hemolytic stress or other genetic determinants associated with the Saudi beta S chromosome, may interact with the -158 C----T substitution and influence gamma globin gene expression in this population.

scholarly journals Hydroxyurea Treatment for Sickle Cell Disease

2002 ◽  
Vol 2 ◽  
pp. 1706-1728 ◽  
Author(s):  
Martin H. Steinberg
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Fetal Hemoglobin ◽  
Hemoglobin Concentration ◽  
Pharmacologic Therapy ◽  
Acute Chest Syndrome ◽  
Cell Disease ◽  
Globin Chains ◽  
Hydroxyurea Treatment ◽  
Erythroid Precursors

High fetal hemoglobin (HbF) levels inhibit the polymerization of sickle hemoglobin (HbS) and reduce the complications of sickle cell disease. Pharmacologic agents that can reverse the switch from γ- to β-chain synthesis — γ-globin chains characterize HbF, and sickle β-globin chains are present in HbS — or selectively increase the proportion of adult erythroid precursors that maintain the ability to produce HbF are therapeutically useful. Hydroxyurea promotes HbF production by perturbing the maturation of erythroid precursors. This treatment increases the total hemoglobin concentration, reduces the vaso-occlusive complications of pain and acute chest syndrome, and attenuates mortality in adults. It is a promising beginning for pharmacologic therapy of sickle cell disease. Still, its effects are inconsistent, trials in infants and children are ongoing, and its ultimate value — and peril — when started early in life are still unknown.

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

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 68-68 ◽  
Author(s):  
Janet L. Kwiatkowski ◽  
Julie Kanter ◽  
Heather J. Fullerton ◽  
Jenifer Voeks ◽  
Ellen Debenham ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
High Risk ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Stroke Prevention ◽  
Cell Disease ◽  
Clinical Series ◽  
The Mean

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

ANTXR1 Intronic Variants Are Associated with Fetal Hemoglobin in the Arab-Indian Haplotype of Sickle Cell Disease

2018 ◽  
Vol 140 (1) ◽  
pp. 55-59 ◽  
Author(s):  
Zhara A. Al-Ali ◽  
Rana K. Fallatah ◽  
Esra A. Aljaffer ◽  
Eman R. Albukhari ◽  
Neriman Sadek Al-Ali ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Real Time Pcr ◽  
Genetic Variants ◽  
Fetal Hemoglobin ◽  
Genetic Mutations ◽  
Cell Disease ◽  
Hbf Level ◽  
Intronic Variants

Disease severity of sickle cell anemia is highly variable, and it is commonly accepted that fetal hemoglobin (HbF) levels play a major role as an ameliorating factor. Investigation of genetic variants have identified several genes to be the principal influencers of HbF regulation. Here, we further elucidated the association of rs4527238 and rs35685045 of ANTXR1 genes in the context of HbF level variance in sickle cell anemia patients of the Arab-Indian haplotype. Samples from 630 sickle cell anemia patients were analyzed for the mutations at 2 specific locations of the ANTXR1 gene by TaqMan®-based real-time PCR. The CC genotype (p = 0.018) of rs4527238 and the TT genotype (p = 0.048) of rs35685045 of ANTXR1 were found to be significantly associated with low HbF expression. The frequency of the CC genotype of rs4527238 was observed to be high in the low HbF patient group compared to the high HbF group (p = 0.009). Likewise, the frequency of the TT genotype of rs35685045 was also high among the low HbF group (p = 0.017). The ANTXR1 genetic mutations and the association with HbF expression in the Arab-Indian haplotype sickle cell patients revealed that the ANTXR1 gene may be a major HbF modulator leading to potential therapeutic options that should be further explored.

Low Fixed Dose Hydroxyurea for the Treatment of Adults with Sickle Cell Disease in Nigeria

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 981-981
Author(s):  
Titilola S. Akingbola ◽  
Bamidele Tayo ◽  
Santosh L. Saraf ◽  
Binal N. Shah ◽  
Chinedu A Ezekekwu ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Low Dose ◽  
Adverse Outcome ◽  
Clinical Malaria ◽  
Fixed Dose ◽  
Cell Disease ◽  
Hemoglobin F ◽  
The Us

Abstract Background: The vast majority of births with sickle cell anemia occur in Africa 1 and early-life mortality, generally before age five years, is as high as 90% 2,3. Hydroxyurea was approved for sickle cell anemia by the US FDA in 1998 but is not commonly used in Africa due to fear of toxicity, lack of awareness and limited availability. Hemoglobin F is a protective factor that decreases severity of sickle cell anemia, and hydroxyurea treatment leads to an increase in hemoglobin F. In the US, hydroxyurea is typically initiated at a dose of 15 mg/kg followed by dose escalations of up to 35 mg/kg if tolerated with a goal of maximal tolerated dose and maximal response in hemoglobin F. Neutropenia and thrombocytopenia are the usual limitations to achieving maximal dose. In the landmark Multicenter Study of Hydroxyurea, the clinical response to hydroxyurea correlated strongly with a reduction in the neutrophil count as well as an increase in the fetal hemoglobin concentration as reflected in percentage of F cells. A striking decrease in pain crises was observed in the first three months of therapy, before dose escalation and before maximal increase in hemoglobin F levels 4. Furthermore, hydroxyurea in the range of 10-15.9 mg/kg/day was reportedly effective in decreasing the frequency of pain episodes in children and adolescents in Oman 5, and hydroxyurea 10 mg/kg/day decreased pain episodes in children and adults with sickle cell anemia in India 6. From these perspectives, we reasoned that a fixed dose of hydroxyurea 10 mg/kg/day is reasonable to investigate in the African setting where the safety in relationship to the resources and infectious exposures is not known. Methods: We assigned 48 sickle cell anemia patients to hydroxyurea 500 mg/day for 24 weeks to determine safety and efficacy; 28 had high-risk disease based on hemoglobin F&lt;8.6% and absence of alpha-thalassemia. We defined a clinically meaningful adverse outcome category as ≥10% of patients developing platelets &lt;50,000/uL, granulocytes &lt;500/uL, clinical malaria and/or active tuberculosis. Picking up refills every four weeks was the adherence metric. We analyzed the results on an intent-to-treat basis. Results: The median (interquartile range) age was 25 (22-27) years and the median hydroxyurea dose 9.8 (9.1-10.4) mg/kg per day. The patients complied with treatment for a median of 20 (16-24) weeks. Four (8.3%) developed a pre-specified adverse outcome: clinical malaria (N=2), thrombocytopenia in combination with malaria (N=1), pulmonary tuberculosis (N=1). During therapy the median hemoglobin increased by 9.0 g/L, mean corpuscular volume by 11.2 fL and body weight by 3.0 kg while median white blood cells declined by 2600 per uL and platelets by 127,000 per uL (P&lt;0.001). The median hemoglobin F increased from 4.1% (2.3-6.3%) at baseline (N=27) to 8.5% (6.3-12.9%) during therapy (N=24) (P&lt;0.001). Conclusion: Our results suggest that low, fixed-dose dose hydroxyurea for sickle cell anemia in Nigeria is associated with a low adverse outcome rate and with improvements in blood counts, hemoglobin F and body weight. The effects on vaso-occlusive episodes and on the risks of recrudescent tuberculosis and malaria-associated thrombocytopenia should be assessed in further studies. Acknowledgment: Supported by a grant from the Doris Duke Foundation. References 1. Williams TN, Obaro SK. Sickle cell disease and malaria morbidity: a tale with two tails. Trends Parasitol 2011;27:315-20. 2. Grosse SD, Odame I, Atrash HK, Amendah DD, Piel FB, Williams TN. Sickle cell disease in Africa: a neglected cause of early childhood mortality. Am J Prev Med 2011;41:S398-405. 3. Makani J, Cox SE, Soka D, et al. Mortality in sickle cell anemia in Africa: a prospective cohort study in Tanzania. PLoS One 2011;6:e14699. 4. Charache S, Barton FB, Moore RD, et al. Hydroxyurea and sickle cell anemia. Clinical utility of a myelosuppressive "switching" agent. The Multicenter Study of Hydroxyurea in Sickle Cell Anemia. Medicine (Baltimore) 1996;75:300-26. 5. Sharef SW, Al-Hajri M, Beshlawi I, et al. Optimizing Hydroxyurea use in children with sickle cell disease: low dose regimen is effective. Eur J Haematol 2013. 6. Patel DK, Mashon RS, Patel S, Das BS, Purohit P, Bishwal SC. Low dose hydroxyurea is effective in reducing the incidence of painful crisis and frequency of blood transfusion in sickle cell anemia patients from eastern India. Hemoglobin 2012;36:409-20. Disclosures Ezekekwu: American Society of Hematology: Other: The Visitor training program was sponsored by ASH. Hsu: AstraZeneca steering committee for HESTIA trial: Research Funding. Gordeuk: Emmaus Life Sciences: Consultancy.

scholarly journals High fetal hemoglobin production in sickle cell anemia in the eastern province of Saudi Arabia is genetically determined

Blood ◽  
1986 ◽  
Vol 67 (5) ◽  
pp. 1404-1410 ◽  
Author(s):  
BA Miller ◽  
M Salameh ◽  
M Ahmed ◽  
J Wainscoat ◽  
G Antognetti ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Fetal Hemoglobin ◽  
Cell Disease ◽  
Chromosome 11 ◽  
Eastern Province ◽  
Genetically Determined ◽  
Hemoglobin Production

Abstract Homozygous sickle cell disease in the eastern province of Saudi Arabia is clinically mild. Circulating fetal hemoglobin levels of 16.0 +/- 7.4% were found in these anemic patients, but only 1.09 +/- 0.97% in their sickle trait parents. To determine whether these sickle cell anemia patients inherit an increased capacity to synthesize fetal hemoglobin, a radioimmunoassay of fetal and adult hemoglobin was performed on erythroid progenitor (BFU-E)-derived erythroblasts from Saudi Arabian sickle cell patients and their parents. Mean fetal hemoglobin content per BFU-E-derived erythroblast from Saudi Arabian sickle cell patients was 6.2 +/- 2.4 pg/cell or 30.4 +/- 8.6% fetal hemoglobin (normal 1.1 +/- 0.7 pg/cell and 5.1 +/- 1.8%). Linear regression analysis of % HbF in peripheral blood versus % HbF per BFU-E- derived cell showed a positive correlation with an r of 0.65. The variance of the intrinsic capacity to produce HbF may account for almost 40% (r2) of the variance of circulating fetal hemoglobin but other factors, particularly selective survival of F cells, must also contribute significantly. Despite virtually normal HbF levels in sickle trait parents of these Saudi patients, mean fetal hemoglobin production per BFU-E-derived erythroblast in these individuals was elevated to 3.42 +/- 1.79 pg/cell or 16.1 +/- 6.4% fetal hemoglobin, and the magnitude of fetal hemoglobin production found in parents correlated with that of the patients. These data indicate that the high fetal hemoglobin in Saudi sickle cell disease is genetically determined but expressed only during accelerated erythropoiesis. Further evidence of such genetic determination was provided by analysis of DNA polymorphisms within the beta-globin gene cluster on chromosome 11. This revealed a distinctive 5′ globin haplotype (+ + - + +) on at least one chromosome 11 in all high F SS and AS tested. The precise relationship of this haplotype to HbF production in this population remains to be defined.

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