scholarly journals The Optimal Cut-Off Level for Hemoglobin A2 to Differentiate between Sickle Cell Disease Genotypes

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2391-2391 ◽  
Author(s):  
Fayiz Al Shueili ◽  
Murtadha K. Al-Khabori ◽  
Salam Al-Kindi ◽  
Yasser Wali ◽  
Shoaib Al-Zadjali
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Roc Analysis ◽  
Beta Thalassemia ◽  
Cell Disease ◽  
R Program ◽  
Alpha Thalassemia ◽  
Thalassemia Trait ◽  
Hemoglobin A2 ◽  
Rbc Count

Abstract Objectives: Hemoglobin A2 (HbA2) is elevated in the presence of beta thalassemia trait and it is used as an indicator of its presence. High-Performance Liquid Chromatography (HPLC) overestimates HbA2 in patients with Sickle Cell Disease (SCD) due to the co-elution of HbS in HbA2 column. The optimal cut-off level of HbA2 to indicate the presence of beta thalassemia trait has not been well established in patients with SCD. We aim to define the optimal cut-off level of HbA2 to differentiate between SS and S/Beta SCD genotype variants. Methods: In this cross-sectional study, we included 241 patients with SCD who have either SS or S/Beta genotype based on their HPLC and the Sickledex test®. The diagnoses were confirmed by the direct sequencing of PCR amplified products of all exons, exon-intron junctions and promoter region of the beta globin gene. We retrieved the following clinical and laboratory variables from the electronic health records: age, gender, Hemoglobin (Hb), Mean Corpuscular Volume (MCV), Red Blood Cell (RBC) count and HbA2. We used the receiver operating curve (ROC) analysis to obtain the optimal cut-off level of HbA2 using the maximum sensitivity and specificity (Youden criteria). All descriptive and analytical statistics were performed using R program. The ROC analysis was performed with the "OptimalCutpoints" package available in R program. Results: Among the 241 patients included in the analysis, SS and S/Bthal patients were 81% and 19% respectively. Male to female ratio was 126:115. Fifty-two percent were using hydroxyurea. The median HbA2 level was 4.5% (Range: 0.0-6.5) in the SS group and 6.5% (Range: 3.5-8.2) in the S/Bthal group. The median Hb, MCV and RBC count was 9.4 g/dL (Range: 5.3 - 15.0), 75 fL (55 - 111) and 3.8 *1012/L (1.9 - 6.3) respectively for the SS group; while it was 9.7 g/dL (6.6 - 12.3), 68 fL (57 - 86) and 4.2 *1012/L (2.5 - 5.4) respectively for the S/Bthal group. The optimal cut-off level for HbA2 was estimated to be 5.7% using a sensitivity of 91% and a specificity of 92%. The positive and negative predictive values were 75% and 98% respectively. The discrimination estimated using the Area Under the Curve (AUC) was 0.936 (95% Confidence Interval: 0.878-0.994). Conclusions: The optimal cut-off HbA2 level to differentiate SCD with the S/Bthal genotype from the SS genotype is 5.7% with a high sensitivity, specificity and discrimination. The unexpected overlap in the MCV and the RBC count is likely related to the high rate of Alpha thalassemia trait in the analyzed population. Incorporation of the presence of alpha thalassemia trait in the analysis may improve the discrimination of MCV and RBC count. Disclosures No relevant conflicts of interest to declare.

scholarly journals Genetic Analysis in the Tanzania Sickle Surveillance Study (TS3): Modifiers of Sickle Cell Disease and Identification of Hemoglobin Variants

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 988-988 ◽  
Author(s):  
Luke R. Smart ◽  
Emmanuela E. Ambrose ◽  
Mwesige Charles ◽  
Arielle G. Hernandez ◽  
Teresa S. Latham ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Board Of Directors ◽  
Sickle Cell ◽  
G6pd Deficiency ◽  
Sickle Cell Trait ◽  
Cell Disease ◽  
Advisory Committees ◽  
Alpha Thalassemia ◽  
Hemoglobin Variants ◽  
Thalassemia Trait

Introduction. Based on sparse historical data, Tanzania ranks fourth globally for the estimated number of annual births with sickle cell disease. Northwest Tanzania is projected to have an especially high burden of sickle cell disease, but no contemporary surveillance data exist to verify this projection. We designed a large prospective study to determine the prevalence of both sickle cell trait and sickle cell disease in northwest Tanzania. Additional objectives included an analysis of two known genetic modifiers of sickle cell disease [alpha thalassemia trait and glucose-6-phosphate dehydrogenase (G6PD) deficiency], as well as genetic variants affecting fetal hemoglobin (HbF) expression and characterization of hemoglobin variants. Methods. The Tanzania Sickle Surveillance Study (TS3) is a prospective cross-sectional study to determine the prevalence of sickle cell trait and disease in an area projected to be at high risk. Dried blood spots (DBS) from all children born to HIV-infected mothers in the 9 regions across northwest Tanzania were collected by the HIV Early Infant Diagnosis (EID) program and transported to a central laboratory at Bugando Medical Centre, a teaching and consultancy hospital in Mwanza. DBS were tested by isoelectric focusing and scored as normal, trait, disease, or variant. Samples scored as disease or variant were retested for confirmation, and then frozen for subsequent genetic analysis. In the US, genomic DNA was extracted from each DBS, and sickle cell disease status was confirmed by PCR and TaqMan genotyping. All confirmed samples were then analyzed for alpha thalassemia trait (rightward -3.7 gene deletion) using quantitative real time PCR, and for G6PD deficiency using three real time PCR probes to distinguish A and B G6PD isoforms, to identify the G6PD A- variant, and to confirm the sex, respectively. Single nucleotide polymorphisms within 3 quantitative trait loci [BCL11A, the HBS1L-MYB intergenic polymorphism (HMIP) region, and the gamma-globin promoter XmnI site] that modify baseline HbF were analyzed using TaqMan genotyping. DBS with hemoglobin variants were investigated for the presence of common variants found in East Africa. Results. Between February 2017 and May 2018, a total of 232 IEF gels were completed by local staff in Tanzania. Among EID samples from children <24 months of age, the median age was 52 days (IQR 41-93 days), and 17,278 unique DBS samples were scored. With 20 samples uninterpretable and 54 samples with missing results, the primary analysis was performed on 17,204 samples. The overall prevalence of sickle cell trait and disease in the entire cohort was 20.3% and 1.2%, respectively, for a sickle allele frequency of 0.114 with Hardy-Weinberg equilibrium. There was some geographical variation between individual districts in both sickle trait (15.2-27.8%) and disease (0.0-4.3%). Hemoglobin variants were rare (0.1%) and included 4 Hb G-Pest, 2 Hb Kenya, and 1 Hb P-Nilotic. Of 143 DBS confirmed to have sickle cell disease and available for further testing, 61 (43%) had one-gene deletion alpha thalassemia trait and 21 (15%) had two-gene deletion. A- G6PD deficiency was detected in 19.2% of males, and 25.7% of females were heterozygous carriers. The minor allelic frequency for known modifiers of HbF were 32.2% C at rs11886868 (BCL11A), 26.6% T at rs1427407 (BCL11A), 32.5% A at rs4671393 (BCL11A), 23.8% G at rs28384513 (HMIP), 4.5% C at rs9399137 (HMIP), and 0% A at rs7482144 (XmnI). Conclusion. The prevalence of sickle cell trait and disease among infants in northwest Tanzania is very high, exceeding 20% trait and 1.2% disease. Regional prevalence data paired with region-specific crude birth rates predict 10,055 births annually in the northwest regions, more than doubling previous estimates. Concomitant alpha thalassemia trait and G6PD deficiency are frequently co-inherited and may affect the phenotype, as well as common genetic modifiers of HbF expression. Our detailed genetic analysis of a geographically representative surveillance cohort provides a foundation for future targeted screening and the introduction of hydroxyurea for treatment of sickle cell disease in northwest Tanzania. Disclosures Ware: Bristol Myers Squibb: Other: Research Drug Donation; Addmedica: Other: Research Drug Donation; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Nova Laboratories: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Novartis: Other: DSMB.

Laparoscopic cholecystectomy in adult patients with beta-thalassemia or sickle cell disease

2005 ◽  
Vol 19 (12) ◽  
pp. 1668-1669 ◽  
Author(s):  
G. Marakis ◽  
T. E. Pavlidis ◽  
K. Ballas ◽  
S. Rafailidis ◽  
A. Sakantamis
Keyword(s):  
Laparoscopic Cholecystectomy ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Adult Patients ◽  
Beta Thalassemia ◽  
Cell Disease

scholarly journals Clinical events in the first decade in a cohort of infants with sickle cell disease. Cooperative Study of Sickle Cell Disease [see comments]

Blood ◽  
1995 ◽  
Vol 86 (2) ◽  
pp. 776-783 ◽  
Author(s):  
FM Gill ◽  
LA Sleeper ◽  
SJ Weiner ◽  
AK Brown ◽  
R Bellevue ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Clinical Course ◽  
The United States ◽  
Beta Thalassemia ◽  
Acute Chest Syndrome ◽  
Cooperative Study ◽  
Cell Disease ◽  
Splenic Sequestration ◽  
Clinical Events

Within the Cooperative Study of Sickle Cell Disease, 694 infants with confirmed sickle cell disease were enrolled at less than 6 months of age. Information about the nature and frequency of complications was collected prospectively over a 10-year period. Painful crises and acute chest syndrome were the most common sickle cell-related events in homozygous sickle cell anemia (SS), hemoglobin SC disease (SC), and S beta thalassemia patients (overall incidence in SS patients of 32.4 and 24.5 cases per 100 person-years, respectively). Bacteremia occurred most frequently in SS children under 4 years of age and in SC patients less than 2 years of age. The mortality rate was low in this cohort compared with that found in previous reports. Twenty children, all with Hb SS, died (1.1 deaths per 100 person-years among SS patients). Infection, most commonly with Streptococcus pneumoniae and Hemophilus influenzae, caused 11 deaths. Two children died of splenic sequestration, 1 of cerebrovascular accident, and 6 of unclear causes. Two patients underwent cholecystectomies, and 17 underwent splenectomies after one or more splenic sequestration crises. The experience of this cohort should reflect closely the true clinical course of those children with Hb SS and Hb SC disease who are observed in sickle cell centers in the United States.

scholarly journals Hydroxyurea increases hemoglobin F levels and improves the effectiveness of erythropoiesis in beta-thalassemia/hemoglobin E disease

Blood ◽  
1996 ◽  
Vol 87 (3) ◽  
pp. 887-892 ◽  
Author(s):  
S Fucharoen ◽  
N Siritanaratkul ◽  
P Winichagoon ◽  
J Chowthaworn ◽  
W Siriboon ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Beta Thalassemia ◽  
Limited Information ◽  
Cell Disease ◽  
Hemoglobin F ◽  
Hemoglobin E ◽  
Globin Chains ◽  
Hb E ◽  
Alpha Globin

Hydroxyurea (HU) is one of several agents that have been shown to enhance hemoglobin (Hb) F levels in patients with sickle cell disease and may be useful as a therapy for beta-globinopathies. However, limited information exists on the effects of HU in patients with thalassemia. Accordingly, we examined the hematologic effects of orally administered HU in 13 patients with beta-thalassemia/Hb E, including four patients who had been splenectomized. These patients were treated with escalating doses (final range, 10 to 20 mg/kg/d) for 5 months and were observed in the outpatient hematology clinic every 2 to 4 weeks. Complete blood counts including reticulocyte counts, amounts of Hb E and Hb F, G gamma:A gamma and alpha:non-alpha globin biosynthetic ratios were evaluated before and during treatment. Almost all patients responded with an average increase of 33% in Hb F levels, from a mean (+/- SD) of 42% +/- 11% to 56% +/- 8% (P < .0001), and a reciprocal decline in the percentage of Hb E from 59% +/- 9% to 49% +/- 8% (P < .001). Reticulocytosis was decreased from a mean (+/- SD) of 18.0% +/- 15.6% to 11.7% +/- 9.1% (P < .05); there was also a slight (10%) but statistically significant increase in hemoglobin levels and an improved balance in alpha:non-alpha globin chains ratios. The side effects were minimal in most patients, although these patients tended to tolerate a lower dose of HU before significant myelosuppression than has been our previous experience in sickle cell disease. One splenectomized patient died of sepsis during the trial. We conclude that increased Hb F production in beta-thalassemia/Hb E patients, with an improvement in the alpha:non-alpha globin ratios and, probably, the effectiveness of erythropoiesis, can be achieved using HU. Longer trials of HU in this population, including at other doses and in combination with other agents, appear warranted.

Beta-Globin Haplotypes and Alpha-Thalassemia 3.7 kb Deletion in Sickle Cell Disease Patients From the Occidental Brazilian Amazon

2016 ◽  
Vol 5 (4) ◽  
pp. 123-128 ◽  
Author(s):  
Janaina Santana Carneiro ◽  
Marilda de Souza Goncalves ◽  
Sergio Roberto Lopes Albuquerque ◽  
Nelson Abrahim Fraiji ◽  
Jose Pereira de Moura Neto
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Brazilian Amazon ◽  
Beta Globin ◽  
Cell Disease ◽  
Alpha Thalassemia

Sickle Cell Trait: A Benign State?

2016 ◽  
Vol 136 (3) ◽  
pp. 147-151 ◽  
Author(s):  
Taiwo R. Kotila
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Dna Analysis ◽  
Sickle Cell Trait ◽  
Beta Thalassemia ◽  
Compound Heterozygous ◽  
Cell Disease ◽  
Benign Condition ◽  
Red Cell Indices ◽  
Heterozygous Form

Background: Sickle cell trait (SCT) is the heterozygous form of sickle cell disease and expectedly should be a benign state with no complications ascribed to it. There are numerous reports challenging its being a benign condition, though this is controversial. Methods and Results: A review of the results of the accompanying investigations done on some of the patients show that beta thalassemia may be responsible for many of the ascribed symptoms and complications. These patients may therefore have sickle cell beta thalassemia, a compound heterozygous form of sickle cell disease. Conclusion: It is important to screen for beta thalassemia using red cell indices and quantitation of the different hemoglobin fractions before attributing any symptoms to SCT. DNA analysis, though useful in ascertaining the presence of the sickle cell gene, is not sufficient. There is the need to exclude the presence of mutations for beta thalassemia, which often is geographical region-specific.

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