Genetics of HbF and HbF Response to Hydroxyurea In Pediatric Sickle Cell Disease: A Multi-Site Pilot Analysis of Candidate SNP Variants

Abstract Abstract 2641 Abstract: Only few genes appear to strongly regulate HbF levels in adults with sickle cell disease (SCD). We aim to: (1) Extend these observations to children with SCD, who likely have better preserved marrow capacity; (2) Assess whether these same genes and other previously identified candidates (Ma et al., 2007) associate with HbF response to HU. Methods: We performed a retrospective analysis from 6 sites (see author affiliations) of children age 5–21 with HbSS or HbS-B thalassemia, untreated with HU or treated for > 6 months at comparable indications and dosing, using %HbF at steady state (baseline) and on HU at or near maximal tolerated dose (MTD), defined as >20mg/kg/day. Subject adherence to HU was assessed by report to their hematology clinician. Siblings were excluded to ensure genetic independence. Candidate 36 SNPs from 2 groups of genes were genotyped: 1) those from reported GWAS: 15 SNPs in BCL11A, 3 in HBS1L-MYB intron, 5' site in B globin, plus sar1; and 2) 15 candidate SNPs exhibiting the largest effect size on HbF with HU treatment (Ma, 2007). SNP genotyping (minor allele frequency (MAF) ranging from 0.10 to 0.50) was performed on the Sequenom MassArray iPLEX platform. (SNP sequences are available.) Duplicate samples assured genotype concordance. Genotype frequency distribution at each SNP was tested for deviations from Hardy-Weinberg equilibrium. MAFs were comparable across our 6 sites, to allele frequencies in HapMap for CEU populations, and CSSCD (Lettre et al., 2008), confirming validity of pooling SNP genotype data from the sites. Using HbF as a continuous trait, genetic associations were assessed from a total of 80 children, 29 of whom are on HU, between each of the 36 SNPs and: a) baseline %HbF; b) %HbF on HU treatment; c) delta %HbF (HU treatment - baseline). For each model, linear regression analysis was used to test quantitative trait and disease trait SNP associations assuming an additive effect for each copy of the minor allele on the phenotype. Resultant p-values were assessed for significance using Bonferroni adjustment for multiple testing. Results: Of the 80 children, comparing the 51 not on HU to those 29 on HU, no significance differences were seen in the distribution and average of baseline %HbF (9.2 vs. 8.9, p=0.820). SNP analyses are summarized in Table 1. 8 SNPs were nominally significantly associated with baseline %HbF. Direction of SNP association differed among these SNPs; some MAF may be reversed in this population compared to those previously reported. For %HbF on HU, the B globin SNP was significantly associated. The delta %HbF on HU is significantly associated with the B globin SNP and nominally so with BCLA11 and SAR1A gene. Our preliminary data begin to extend findings of specific genetic variants regulating HbF to children with SCD. Early data suggest that HbF in response to HU may share some of the mechanisms governing baseline HbF in SCD, not surprising given the commonality of enhanced erythropoiesis. Subject recruitment and analyses are on-going. Disclosure: Off Label Use: Hydroxyurea has not been FDA approved for use in children with sickle cell disease, a topic of the submitted abstract.

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Genetic Variation In MYH9 Is Associated with Sickle Cell Disease Nephropathy

Blood ◽

10.1182/blood.v116.21.1648.1648 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1648-1648

Author(s):

Emmanuel Okocha ◽

Melanie Garrett ◽

Karen Soldano ◽

Laura M. De Castro ◽

Jude Jonassaint ◽

...

Keyword(s):

High Risk ◽

African Americans ◽

Sickle Cell Disease ◽

Renal Dysfunction ◽

Sickle Cell ◽

Heavy Chain ◽

Multiple Testing ◽

Risk Haplotype ◽

Cell Disease ◽

Data Set

Abstract Abstract 1648 Background: Renal failure occurs in 5–18% of sickle cell disease (SCD) patients and is a major risk factor for early mortality. However, there is no established method of identifying SCD patients that are at high risk of developing this outcome prior to the appearance of proteinuria, and its pathobiology is not well understood. The non-muscle myosin heavy chain ll-A (MYH9) gene, which encodes the heavy chain of myosin II-A in the podocyte cytoskeleton, has been identified as driving the high risk of focal segmental glomerulosclerosis (FSGS) and end-stage renal disease in African Americans. Methods: We genotyped 26 single nucleotide polymorphisms (SNPs) in the MYH9 gene in 521 unrelated adult (18 – 83 years) SCD patients who had been screened for proteinuria. Logistic regression was used to determine if the SNPs predicted risk for proteinuria among the patients. Results: Of 521 adult SCD patients studied, 140 had proteinuria, while 381 did not. On average, subjects with proteinuria were 6 years older than subjects without proteinuria (p<0.0001). The odds of having proteinuria increased by 1.04 (4.2%) for every one year increase in age, starting at age 18. We found association with proteinuria for 8 SNPs in MYH9, with nominal p values ranging from 0.025 to 0.0001. Two of these SNPs (rs5756129 and rs1005570) had been previously associated with FSGS in African-Americans without SCD (Kopp et al., 2008). Five SNPs remained significant after correcting for multiple testing (p < 0.003) using the method described by Li and Ji (2005), and a risk haplotype significantly associated with proteinuria (p=0.001) was identified. The frequency of proteinuria among individuals who were homozygous for the risk genotype ranged from 40–50% for each of the five SNPs remaining significant after adjusting for multiple testing, while the risk of proteinuria for individuals who did not have that genotype ranged from 20–30%. Glomerular filtration rate was negatively correlated with proteinuria (r = -0.25, p < 0.0001) but was not itself associated with MYH9 SNPs. Although we tested for association of proteinuria with the two most significant BMPR1B SNPs found by Nolan et al. (2007), neither were associated with proteinuria or GFR in age-adjusted analysis of our cohort, although we did observe nominal evidence for association of a different BMPR1B SNP with proteinuria in our data set (rs1434536, p=0.004, age adjusted). To further investigate a possible connection between BMPR1B and MYH9, we performed regression analyses including BMPR1B SNPs (rs1434536, rs2240036 and rs4145993) and the MYH9 haplotype in the models and controlled for age. In these analyses, the MYH9 risk haplotype remained a significant predictor of proteinuria and was only borderline associated with GFR. None of the BMPR1B SNPs were associated with proteinuria or GFR when the MYH9 haplotype was included in the model, suggesting that MYH9 is likely the more important contributor to these processes in our data set. Conclusion: Our data provide additional support for the role of MYH9 in renal dysfunction among African Americans. A specific haplotype appears to be associated with increased risk for proteinuria among patients with SCD. The association of MYH9 with renal dysfunction in SCD provides insight into the pathophysiology of this process and may lead to early identification of patients at risk and, ultimately, to new modes of therapeutic intervention. Disclosures: De Castro: GlycoMimetics: . Telen:GlycoMimetics: Consultancy, clinical trial sponsorship.

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Abstract 2303: Prospective Correlation of Echocardiography Findings with Hematologic and Pulmonary Function Parameters in Children with Sickle Cell Disease

Circulation ◽

10.1161/circ.116.suppl_16.ii_503-b ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Niti Dham ◽

Craig Sable ◽

Caterina P Minnitti ◽

Andrew Campbell ◽

Manuel Arteta ◽

...

Keyword(s):

Regression Analysis ◽

Sickle Cell Disease ◽

Pulmonary Function ◽

Diastolic Function ◽

Sickle Cell ◽

Linear Regression Analysis ◽

Cell Disease ◽

Pulmonary Pressure ◽

Prospective Comparison ◽

Lv Mass

Background Adults with sickle cell disease (SCD) have an increased prevalence of pulmonary hypertension (PAH), associated with significant morbidity and mortality. This finding has not been validated in children. We carried out a prospective comparison of echocardiography (echo) data between SCD and control patients and a correlation between echo findings and hematologic and pulmonary function testing (PFT) in SCD patients. Methods Children with SCD and age and gender matched controls were prospectively enrolled during well visits. Each subject underwent a history and examination, echo, hematologic testing, and PFT. Echo data was compared between SCD patients and controls, and regression analysis was performed to assess for correlation between echo parameters and anemia, markers of hemolysis, and PFT in SCD patients. Results Of the 194 SCD patients and 29 controls enrolled, 180 SCD patients and 26 controls had measurable tricuspid valve regurgitation (TR) to estimate systolic pulmonary pressure. TR, left ventricle (LV) size and LV mass were significantly higher in children with SCD (Table 1 ). Linear regression analysis in SCD patients showed that TR, LV size, LV mass, and diastolic function (E/E TDI ) correlated significantly with hemoglobin, markers of hemolysis, and obstructive pulmonary disease (Table 2 ). There was no correlation between echo parameters and age, blood pressure, or measures of restrictive lung disease Conclusion Children with SCD have higher estimated pulmonary pressure, LV size and mass and a trend toward worse diastolic function when compared to controls. TR and LV size and mass correlate with anemia, hemolysis, and obstructive patterns on PFT. Table 1 - Comparative Data Table 2 - Regression Analysis

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A Randomized Clinical Hypnosis Pilot Study: Improvements in Self-Reported Pain Impact in Adults with Sickle Cell Disease

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2021/5539004 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Gwenyth R. Wallen ◽

Kimberly R. Middleton ◽

Narjis B. Kazmi ◽

Li Yang ◽

Alyssa T. Brooks

Keyword(s):

Sickle Cell Disease ◽

Coping Strategies ◽

Sickle Cell ◽

Current Evidence ◽

Control Group ◽

Cell Disease ◽

Significant Group ◽

Biobehavioral Intervention ◽

Bonferroni Adjustment ◽

Patient Reported

Sickle cell disease (SCD) is characterized by recurrent painful vasoocclusive crises. Current evidence focuses on the frequency of acute pain crises resulting in emergency department use and nonplanned inpatient hospital admissions; yet few studies focus on pain sequelae outside the healthcare system or how individuals self-manage their chronic SCD-related pain. This study investigated the feasibility of a biobehavioral intervention as an adjunct nonpharmacological therapy to assist in the self-management of chronic pain. A randomized, controlled clinical trial of hypnosis was conducted in outpatients with SCD (n = 31). Patient-reported outcomes (PROs) administered at baseline, five, and twelve weeks from both groups included pain frequency, intensity, and quality (Pain Impact Scale (PIQ) and Numerical Rating Scales); anxiety (State-Trait Anxiety Inventory), coping strategies (Coping Strategies Scale), sleep (Pittsburgh Sleep Quality Index (PSQI)), and depression (Beck Depression Inventory (BDI)). The same PROs were collected at weeks seventeen and twenty-four from the control group after the crossover. No significant group by time interaction effects were found in any of the PROs based on the repeated-measures mixed models. The PIQ and PSQI scores decreased over time in both groups. Post hoc pairwise comparisons with the Bonferroni adjustment indicated that the mean PIQ score at baseline decreased significantly by week 12 ( p = 0.01) in the hypnosis group. There were no significant changes across time before and after the crossover in any of the PROs in the control group. As suggested by these findings, pain impact and sleep in individuals with SCD may be improved through guided mind-body and self-care approaches such as hypnosis.

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Inflammatory Polymorphisms Link the Risk of Acute Chest Syndrome with Asthma in Adults with Sickle Cell Disease

Blood ◽

10.1182/blood.v118.21.1072.1072 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1072-1072 ◽

Cited By ~ 1

Author(s):

Latorya A. Barber ◽

Karen Soldano ◽

Melanie Garrett ◽

Eugene P. Orringer ◽

James R. Eckman ◽

...

Keyword(s):

Risk Factors ◽

Regression Analysis ◽

Sickle Cell Disease ◽

Sickle Cell ◽

Acute Chest Syndrome ◽

Genome Wide Association Studies ◽

Genetic Associations ◽

Cell Disease ◽

Inflammatory Genes ◽

Increased Risk

Abstract Abstract 1072 Acute chest syndrome (ACS) is a common cause of death among patients with sickle cell disease (SCD). There is increasing evidence that asthma may represent a significant risk factor for the development of ACS in children with SCD and it is associated with increased mortality (Newaskar, et al. 2010; Poulter, et al. 2011).The incidence of ACS in adolescent SCD patients is associated with the occurrence of asthma and genetic polymorphisms in NOS1 and NOS3 (Duckworth, et al. 2007). Polymorphisms in inflammatory genes, including IL-12A, IL-12B, and IL-4 receptor have been previously associated with the incidence and severity of asthma in non-SCD cohorts (Chen, et al. 2011; Mannino, et al. 2002; Caggana, et al. 1999). These data imply that the association of asthma with increased risk for ACS in adolescent SCD patients has a genetic component. However, the clinical and genetic associations among ACS, asthma, and inflammation have not been evaluated in adults with SCD. Our goals were (1) to identify clinical risk factors for ACS and (2) to identify single nucleotide polymorphisms (SNPs) in inflammatory genes associated with asthma and ACS in our population of adult SCD patients. All clinical data were collected using standardized report forms. Use of bronchodilators served as a surrogate for the occurrence of asthma. We analyzed 94 SNPs within 14 inflammatory genes in 675 DNA samples from SCD patients ascertained from Duke University, University of North Carolina-Chapel Hill, and Emory University. In order to achieve greater coverage in our genes of interest, SNP genotyping data was derived from two methods, Taqman genotyping assays from Applied Biosystems and genome-wide association studies (GWAS) using the Illumina-610 SNP array. Clinical and genetic associations with ACS and use of bronchodilators were examined using regression analysis (PROC LOGISTIC or GLM in SAS version 9.2, Cary, NC). The incidence of ACS in our population was 73%. Six percent of our population used bronchodilators, similar to the overall incidence of asthma in the US population (Newaskar et al., 2011). We observed a significant association between the use of bronchodilators and the incidence of ACS in our dataset, such that the percentage of patients with a history of ACS among bronchodilator users was 90% versus 73% in non-users (p=0.028). ACS was also associated with an increase in pain episodes (OR=1.6, p<0.0001), narcotics use (OR=1.5, p=0.0002), WBC counts (p=0.04), platelet counts (p=0.007), and higher mean hemoglobin (Hb) levels (p=0.003). ACS was also associated with decreased Hb F levels (p=0.05). After controlling for age, gender, and use of hydroxyurea, SNPs in IL-12A (rs568408; p=0.007), IL-12B (rs2195940; p=0.022), and IL-4R (rs3024537; p=0.049) were significantly associated with ACS. In addition, IL-12A (rs568408; p=0.037), IL-12B (rs2853694; p=0.009), and IL-4R (rs2283563; p=0.031) were significantly associated with the use of bronchodilators in our adult SCD cohort. None of the SNPs in IL=12B or IL-4R were found to be in linkage disequilibrium (LD) with each other. After multiple regression analysis, SNPs in IL-12A (rs568408; p=0.013), IL-12B (rs2195940; p=0.01), and IL-4R (rs3024537; p=0.02) remained significantly associated with ACS, and SNPs in IL-12A (rs568408; p=0.048), IL-12B (rs2853694; p=0.005), and IL-4R (rs2283563; p=0.01) remained significantly associated with use of bronchodilators. The functional significance of these SNPs is presently unknown. All of the polymorphisms are intronic except for rs568408, located in the 3'untranslated region of IL-12A. In summary, our findings in adult SCD patients support previous data in children demonstrating associations among inflammatory markers and asthma with the occurrence of ACS. Our data also support the association between asthma and increased risk of ACS. Finally, we have identified potential genetic risk factors for both asthma and ACS in adults with SCD. Our findings suggest that further investigation into the role of these inflammatory mediators in pulmonary dysfunction in SCD is warranted. Disclosures: No relevant conflicts of interest to declare.

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Beneficial Effect of Intravenous Dexamethasone in Children With Mild to Moderately Severe Acute Chest Syndrome Complicating Sickle Cell Disease

Blood ◽

10.1182/blood.v92.9.3082.421k15_3082_3089 ◽

1998 ◽

Vol 92 (9) ◽

pp. 3082-3089 ◽

Cited By ~ 7

Author(s):

Juan Carlos Bernini ◽

Zora R. Rogers ◽

Eric S. Sandler ◽

Joan S. Reisch ◽

Charles T. Quinn ◽

...

Keyword(s):

Sickle Cell Disease ◽

Beneficial Effect ◽

Hospital Stay ◽

Sickle Cell ◽

Linear Regression Analysis ◽

Therapeutic Modality ◽

Acute Chest Syndrome ◽

High Dose ◽

Blood Transfusions ◽

Cell Disease

Acute chest syndrome (ACS) in patients with sickle cell disease (SCD) has historically been managed with oxygen, antibiotics, and blood transfusions. Recently high-dose corticosteroid therapy was shown to reduce the duration of hospitalization in children with SCD and vaso-occlusive crisis. Therefore, we chose to assess the use of glucocorticoids in ACS. We conducted a randomized, double-blind placebo-controlled trial to evaluate the efficacy and toxicity of intravenous dexamethasone (0.3 mg/kg every 12 hours × 4 doses) in children with SCD hospitalized with mild to moderately severe ACS. Forty-three evaluable episodes of ACS occurred in 38 children (median age, 6.7 years). Twenty-two patients received dexamethasone and 21 patients received placebo. There were no statistically significant differences in demographic, clinical, or laboratory characteristics between the two groups. Mean hospital stay was shorter in the dexamethasone-treated group (47 hours v 80 hours; P = .005). Dexamethasone therapy prevented clinical deterioration and reduced the need for blood transfusions (P < .001 and = .013, respectively). Mean duration of oxygen and analgesic therapy, number of opioid doses, and the duration of fever was also significantly reduced in the dexamethasone-treated patients. Of seven patients readmitted within 72 hours after discharge (six after dexamethasone; P = .095), only one had respiratory complications (P = 1.00). No side effects clearly related to dexamethasone were observed. In a stepwise multiple linear regression analysis, gender and previous episodes of ACS were the only variables that appeared to predict response to dexamethasone, as measured by lengh of hospital stay. Intravenous dexamethasone has a beneficial effect in children with SCD hospitalized with mild to moderately severe acute chest syndrome. Further study of this therapeutic modality is indicated. © 1998 by The American Society of Hematology.

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Factors associated with abnormal cerebral blood flow in Egyptian children with sickle cell disease

Clinical and Translational Neuroscience ◽

10.1177/2514183x20911351 ◽

2020 ◽

Vol 4 (1) ◽

pp. 2514183X2091135

Author(s):

Foad Abd-Allah ◽

Mona Eltagui ◽

Alshaimaa Mahmoud Aboulfotooh ◽

Nirmeen Adel Kishk ◽

Mohammad Ahmed Farrag ◽

...

Keyword(s):

Sickle Cell Disease ◽

Blood Transfusion ◽

Sickle Cell ◽

Linear Regression Analysis ◽

Cell Disease ◽

Predictive Tool ◽

Cross Sectional ◽

Transfusion Therapy ◽

Egyptian Children ◽

Annual Frequency

Background: Transcranial Doppler (TCD) is a well-established tool for cerebrovascular assessment. Estimating the flow velocity across the intracranial arteries helps to identify children with sickle cell anaemia who are at risk for stroke. Objective: Our aim is to correlate TCD findings with clinical condition in children with sickle cell disease (SCD) to determine the value of TCD assessment as a predictive tool for stroke in SCD and to identify any association of TCD findings with disease severity, transfusion therapy and treatment administered. Methods: Eighty-five paediatric SCD patients aged from 3 years to 18 years of both genders who were followed up at the Hematology Clinic of New Children’s Hospital at Cairo University were included in this cross-sectional observational study. All our participants underwent routine laboratory investigations and TCD assessments. Results: Oof the 85 patients, two patients (2.3%) died before completing the TCD study and eventually 83 patients were included in the analysis. Seventeen (20.5%) patients had abnormal TCD findings, seven (8.4%) patients showed high-risk findings and 10 (12.1%) patients had conditional flow pattern. Logistic linear regression analysis confirmed that annual frequency of blood transfusion and hydroxyurea (HU) dose were associated with a decreased risk of abnormal TCD findings. Conclusion: The current study demonstrates that our TCD data reproduce the findings of other studies and that it is very likely the results from large trials are applicable for Egyptian children. The annual frequency of blood transfusion and HU dose were associated with a decreased frequency of abnormal TCD findings.

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Beneficial Effect of Intravenous Dexamethasone in Children With Mild to Moderately Severe Acute Chest Syndrome Complicating Sickle Cell Disease

Blood ◽

10.1182/blood.v92.9.3082 ◽

1998 ◽

Vol 92 (9) ◽

pp. 3082-3089 ◽

Cited By ~ 143

Author(s):

Juan Carlos Bernini ◽

Zora R. Rogers ◽

Eric S. Sandler ◽

Joan S. Reisch ◽

Charles T. Quinn ◽

...

Keyword(s):

Sickle Cell Disease ◽

Beneficial Effect ◽

Hospital Stay ◽

Sickle Cell ◽

Linear Regression Analysis ◽

Therapeutic Modality ◽

Acute Chest Syndrome ◽

High Dose ◽

Blood Transfusions ◽

Cell Disease

Abstract Acute chest syndrome (ACS) in patients with sickle cell disease (SCD) has historically been managed with oxygen, antibiotics, and blood transfusions. Recently high-dose corticosteroid therapy was shown to reduce the duration of hospitalization in children with SCD and vaso-occlusive crisis. Therefore, we chose to assess the use of glucocorticoids in ACS. We conducted a randomized, double-blind placebo-controlled trial to evaluate the efficacy and toxicity of intravenous dexamethasone (0.3 mg/kg every 12 hours × 4 doses) in children with SCD hospitalized with mild to moderately severe ACS. Forty-three evaluable episodes of ACS occurred in 38 children (median age, 6.7 years). Twenty-two patients received dexamethasone and 21 patients received placebo. There were no statistically significant differences in demographic, clinical, or laboratory characteristics between the two groups. Mean hospital stay was shorter in the dexamethasone-treated group (47 hours v 80 hours; P = .005). Dexamethasone therapy prevented clinical deterioration and reduced the need for blood transfusions (P < .001 and = .013, respectively). Mean duration of oxygen and analgesic therapy, number of opioid doses, and the duration of fever was also significantly reduced in the dexamethasone-treated patients. Of seven patients readmitted within 72 hours after discharge (six after dexamethasone; P = .095), only one had respiratory complications (P = 1.00). No side effects clearly related to dexamethasone were observed. In a stepwise multiple linear regression analysis, gender and previous episodes of ACS were the only variables that appeared to predict response to dexamethasone, as measured by lengh of hospital stay. Intravenous dexamethasone has a beneficial effect in children with SCD hospitalized with mild to moderately severe acute chest syndrome. Further study of this therapeutic modality is indicated. © 1998 by The American Society of Hematology.

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Selenium Status and Hemolysis in Sickle Cell Disease Patients

Nutrients ◽

10.3390/nu11092211 ◽

2019 ◽

Vol 11 (9) ◽

pp. 2211 ◽

Cited By ~ 1

Author(s):

Emília Delesderrier ◽

Cláudia S. Cople-Rodrigues ◽

Juliana Omena ◽

Marcos Kneip Fleury ◽

Flávia Barbosa Brito ◽

...

Keyword(s):

Sickle Cell Disease ◽

Linear Regression ◽

Sickle Cell ◽

Complete Blood Count ◽

Hematological Parameters ◽

Linear Regression Analysis ◽

Selenium Deficiency ◽

Alpha Tocopherol ◽

Cell Disease ◽

Chronic Hemolysis

Sickle cell disease (SCD) is a genetic hemoglobinopathy characterized by chronic hemolysis. Chronic hemolysis is promoted by increased oxidative stress. Our hypothesis was that some antioxidant micronutrients (retinol, tocopherol, selenium, and zinc) would be determinant factors of the degree of hemolysis in SCD patients. We aimed to investigate the nutritional adequacy of these antioxidants and their relationships to hemolysis. The study included 51 adult SCD patients regularly assisted in two reference centers for hematology in the State of Rio de Janeiro, Brazil. Serum concentrations of retinol, alpha-tocopherol, selenium, and zinc were determined by high-performance liquid chromatography or atomic absorption spectrometry. Hematological parameters (complete blood count, reticulocyte count, hemoglobin, direct and indirect bilirubin, total bilirubin, lactate dehydrogenase) and inflammation markers (leukocytes and ultra-sensitive C-reactive protein) were analyzed. A linear regression model was used to test the associations between the variables. Most patients presented selenium deficiency and low selenium consumption. Linear regression analysis showed that selenium is the main determinant of hemolysis among the antioxidant nutrients analyzed. Thus, data from this study suggest that the nutritional care protocols for patients with SCD should include dietary sources of selenium in order to reduce the risk of hemolysis.

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DNA Variants Involved in Regulation of Fetal Hemoglobin in Mexican Patients with Sickle Cell Disease. a Preliminary Analysis

Blood ◽

10.1182/blood-2020-139812 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 30-31

Author(s):

Lourdes Del Carmen Rizo-De La Torre ◽

Francisco Javier Perea-Díaz ◽

Efrain Aquino ◽

Martha Venegas ◽

Carmela Hernández-Carbajal ◽

...

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Preliminary Analysis ◽

Fetal Hemoglobin ◽

Minor Allele ◽

Allele Frequencies ◽

The Other ◽

Cell Disease ◽

Dna Variants ◽

Allele Count

HbS (HBB:c.20A>T, beta 6 Glu>Val) is a frequent Hb variant in Mexico, in particular in some regions close to the Pacific and Atlantic Oceans, with carrier frequencies from 0.5 to 12.8%, therefore Sickle Cell Disease patients are often seen in those regions. It is well known that increased levels of Fetal Hemoglobin (HbF) ameliorates the clinical complications of sickle cell disease. Several genetic studies have identifiedBCL11A,HBS1L-MYB(intergenic region),HBG2andHBBP1genes, among others, to be involved in HbF regulation; DNA variants in theselociare associated to elevated HbF. The aim of present study was to analyze 15 variants in HbF regulatorylociin Mexican patients with Sickle Cell Disease. About 10 mL of peripheral blood was collected in EDTA for hematological and molecular testing from 24 sickle cell anemia patients (S/S) and 15 sickle cell trait carriers (S/A) from Southern Mexico, 13 were from the state of Guerrero and 26 from Chiapas. All subjects voluntarily agreed to participate in this study and gave signed informed consent; underaged patients' consent was obtained from their parents; all procedures were performed according to the ethical principles of the Declaration of Helsinki. Hemoglobin S genotype was determined by Sanger sequencing; DNA variants genotyping was performed by qPCR using commercial Taqman probes for the following variants: inBCL11Ars11886868, rs4671393, rs7557939, rs1427407, rs766432, rs6706648, rs7599488; inHBS1L-MYBrs7776054, rs28384513, rs9399137, rs4895441, rs9402686, rs1320963, inHBG2rs7482144 and inHBBP1rs10128556. Hematological and clinical data were analyzed by IBM SPSS v24®. A total of 39 sickle cell patients were studied, twenty-one patients were male and 18 were female (53.8% and 46.2% respectively). Thirty-two were pediatric age patients and 7 adults. Anemia was observed in all S/S patients, eight had severe anemia (<8 g/dL); on the other hand, only 5/15 S/A patients had anemia (10 - 12 g/dL); HbF over 5% was observed in 23/24 S/S patients and in 13/15 S/A had HbF from 2% - 5%. Nineteen S/S patients were treated with hydroxyurea and presented less severe phenotype and more elevated HbF, however, the statistical analysis showed no significant differences (12.9%vs8.9%p=0.248) (Table 1). Genotype and allele frequencies are displayed in Table 2. All minor alleles were observed in frequencies over 0.05, the mo2st commonly observed minor allele wasBCL11Ars1427407 (0.69), and the less frequently observed wasHBBP1rs101028556 (0.08). The allele frequencies of four HbF regulating variants were significant different from those reported for Mexican ancestry population (MXL) in 1000 Genome database (rs11886868 C>T, rs4671393 A>G, rs7599488 C>T and rs10128556 C>T), however, the analyzed sample in this study is undersized and is not representative of the global Mexican population. No differences were observed when comparing allele frequencies from GuerrerovsChiapas patients, nor S/SvsS/A. The correlation analysis of minor allele count (MAC) and HbF demonstrated no association when comparing it to HbF levels. Likewise, the analysis was performed onBCL11AandHBS1L-MYBvariants and showed no significant correlations. There was also no correlation between MAC and the other hematological parameters (RBC, Hb, PCV, MCV and MCH). We report the first study of HbF regulating DNA variants in Mexican sickle cell disease patients. The preliminary analysis of HbFvsminor allele count showed no relation of total MAC and increased HbF, neither with the variants ofBCL11AorHBS1L-MYB. Disclosures No relevant conflicts of interest to declare.

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BCL11A Polymorphism and HbF Response to Hydroxyurea in Adult Patients with Sickle Cell Disease

Blood ◽

10.1182/blood.v118.21.1051.1051 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1051-1051

Author(s):

Philip Sobash ◽

Ferdane Kutlar ◽

Harrison C. Brown ◽

Betsy Clair ◽

Abdullah Kutlar

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

Conflicts Of Interest ◽

Extended Period ◽

Minor Allele ◽

Maximal Response ◽

Cell Disease ◽

Promoter Polymorphisms ◽

Hemoglobin F ◽

Wide Range

Abstract Abstract 1051 Several genetic polymorphisms are known to influence baseline hemoglobin F (HbF) levels in patients with sickle cell disease (SCD). These include XmnI polymorphisms in the Gγ globin promoter, polymorphisms of HBS1L-MYB and more recently BCL11A. Over the past several years, many studies have shown that polymorphisms in the BCL11A gene are strongly associated with baseline HbF levels in various populations with SCD. The strongest association has been found with a SNP (G→A) in the intron2 of the BCL11A gene (rs4671393). SCD patients on hydroxyurea (HU) therapy display a wide range of HbF responses. The factors underlying this heterogeneity are not clearly delineated. We undertook a study of the BCL11A rs4671393 polymorphism in a population of adult SCD patients who have been on HU therapy for an extended period. Fifty-nine African-American patients with SCD (25 male, mean age 33.9 and 34 female, mean age 34.5) were studied for BCL11A rs4671393 polymorphism and its correlation to HbF response (percent change in HbF from baseline to maximal response). The minor allele frequency (MAF) of A was 0.288. The distribution of HbF response (δHbF) was plotted against the genotype and is shown in the figure. As can be seen, patients with an A allele had a higher δHbF (12.1%) as opposed to those with the wild type (G/G), which was at 10.6%. Those homozygous for the minor allele (A/A) showed a 10.8% increase in HbF in response to HU therapy. These results are suggestive of a higher HbF response to HU when an A allele is present at this position. The number of homozygous for the minor allele are too small to reach a definite conclusion. Disclosures: No relevant conflicts of interest to declare.

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