Hemoglobin A2 values in sickle cell disease patients quantified by high performance liquid chromatography and the influence of alpha thalassemia

Introduction: Since 2003, only few cases of sickle cell disease have officially been reported in Nepalese medical journals, and all reported patients belong to the Tharu ethnic group of Nepal. This is the first study that details sickle cell disease and carrier in 1250 individuals in western Nepal. Methods: This is a retrospective review of the patients and carriers of sickle cell disease diagnosed by either a positive haemoglobin electrophoresis report or a positive high performance liquid chromatography (HPLC) report. Analysis was done using SPSS 20. Results: Out of the 1250 individuals, 51.4% were females. 601 (48.08%) were patients with a form of sickle cell disease, the mean age was 24.5  12 yrs years. Most patients came from Bardiya district. Most common symptoms were related to joint pain. The patients and carriers of sickle cell disease were mostly from Tharu ethnic group (97.7%). Conclusion: These data suggest that sickle cell disease and other haemoglobinopathies are more prevalent than previously reported among members of the Tharu ethnic group and other residents of western Nepal. More research is imperative to assess the burden of the sickle cell disease and other haemoglobinopathies in Nepal.

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

Blood ◽

10.1182/blood-2018-99-118697 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 2391-2391 ◽

Cited By ~ 1

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.

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THE EFFECT OF ALPHA THALASSEMIA, HBF and HBC ON HAEMATOLOGICAL PARAMETERS OF SICKLE CELL DISEASE PATIENTS IN IBADAN, NIGERIA.

Mediterranean Journal of Hematology and Infectious Diseases ◽

10.4084/mjhid.2022.001 ◽

2022 ◽

Vol 14 (1) ◽

pp. e2022001

Author(s):

FASOLA ATINUKE

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

High Performance ◽

Hematological Parameters ◽

Globin Gene ◽

Health Centre ◽

Full Blood Count ◽

Cell Disease ◽

Alpha Thalassemia ◽

Alpha Gene

Background: Sickle cell disease is a protean disease with limited data on the phenotypic and genetic variants in Nigeria. This study was conducted to provide baseline data on these variants by characterizing the existing forms of sickle cell disease and correlating these with basic hematological parameters. Methods: Adult and pediatric patients with SCD were recruited from a tertiary health centre in Nigeria. Patients were age and sex matched with healthy controls. Blood samples were obtained for Full Blood Count, phenotyping by High Performance Liquid Chromatography and genotyping for alpha thalassemia by multiplex gap polymerase chain reaction. Data analysis was done using IBM SPSS statistics version 23. Results: A total of 130 patients with sickle cell disease and 117 controls were studied. Alpha thalassemia in the study population was due to a 3.7kb deletion in the alpha globin gene cluster at a prevalence of 45.4% in the patients and 47% in controls. The prevalence of the various existing forms of SCD genotype was: Homozygous S without alpha gene deletion (HbSS)- 39.2%; HbSC - 10.8%; HbSα+1- 35.4%; HbSα+2 - 6.9% and HbSF- 7.7%. HbA2 was significantly elevated in individuals with two alpha gene deletions (HbSα+2). HbF and HbA2 were negatively correlated with each other (r= -0.587, p < 0.001). Individuals with the HbSC genotype followed by HbSα+2 had the best hematological parameters. Conclusions: Hematological parameters varied with hemoglobin genotype. The C hemoglobin and homozygous alpha thalassemia deletion had better ameliorating effect on SCD hematological parameters than the F hemoglobin in this population.

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Voxelotor Treatment Interferes With Quantitative and Qualitative Hemoglobin Variant Analysis in Multiple Sickle Cell Disease Genotypes

American Journal of Clinical Pathology ◽

10.1093/ajcp/aqaa067 ◽

2020 ◽

Vol 154 (5) ◽

pp. 627-634

Author(s):

Nicola J Rutherford-Parker ◽

Sean T Campbell ◽

Jennifer M Colby ◽

Zahra Shajani-Yi

Keyword(s):

Sickle Cell Disease ◽

Sickle Cell ◽

High Performance ◽

Clinical Laboratory ◽

The United States ◽

Cell Disease ◽

Hemoglobin Variant ◽

Hbd Punjab ◽

The Impact

Abstract Objectives Voxelotor was recently approved for use in the United States as a treatment for sickle cell disease (SCD) and has been shown to interfere with the quantitation of hemoglobin (Hb) S percentage. This study aimed to determine the effect of voxelotor on the quantitation of hemoglobin variant levels in patients with multiple SCD genotypes. Methods In vitro experiments were performed to assess the impact of voxelotor treatment on hemoglobin variant testing. Whole blood samples were incubated with voxelotor and then analyzed by routinely used quantitative and qualitative clinical laboratory methods (high-performance liquid chromatography [HPLC], capillary zone electrophoresis [CZE], and acid and alkaline electrophoresis). Results Voxelotor modified the α-globin chain of multiple hemoglobins, including HbA, HbS, HbC, HbD-Punjab, HbE, HbA2, and HbF. These voxelotor-hemoglobin complexes prevented accurate quantitation of multiple hemoglobin species, including HbS, by HPLC and CZE. Conclusions Technical limitations in quantifying HbS percentage may preclude the use of HPLC or CZE for monitoring patients treated with voxelotor. Furthermore, it is unclear whether HbS-voxelotor complexes are clinically equivalent to HbS. Consensus guidelines for reporting hemoglobin variant percentages for patients taking voxelotor are needed, as these values are necessary for determining the number of RBC units to exchange in acute situations.

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Multicenter Evaluation of HemoTypeSC as a Point-of-Care Sickle Cell Disease Rapid Diagnostic Test for Newborns and Adults Across India

American Journal of Clinical Pathology ◽

10.1093/ajcp/aqz108 ◽

2019 ◽

Vol 153 (1) ◽

pp. 82-87 ◽

Cited By ~ 3

Author(s):

Malay B Mukherjee ◽

Roshan B Colah ◽

Pallavi R Mehta ◽

Nikhil Shinde ◽

Dipty Jain ◽

...

Keyword(s):

Sickle Cell Disease ◽

Newborn Screening ◽

Sickle Cell ◽

High Performance ◽

Screening Program ◽

Point Of Care ◽

Genetic Disorder ◽

Cell Disease ◽

Point Of Care Test ◽

Tribal Areas

Abstract Objectives Sickle cell anemia is the commonest genetic disorder in India, and the frequency of the sickle cell gene is very high in the remote tribal areas where facilities are generally limited. Therefore, a rapid and affordable point-of-care test for sickle cell disease is needed. Methods The diagnostic accuracy of HemoTypeSC was evaluated against automated high-performance liquid chromatography (HPLC) as the gold standard for its efficacy in a newborn screening program. Results A total of 1,559 individuals (980 newborns and 579 adults) from four participating centers were analyzed by both methods. HemoTypeSC correctly identified 209 of 211 total hemoglobin (Hb) SS cases, for a 99.1%/99.9% total HbSS sensitivity/specificity. Overall, HemoTypeSC exhibited sensitivity and specificity of 98.1% and 99.1% for all possible phenotypes (HbAA, HbAS, and HbSS) detected. HPLC is relatively expensive and not available in most laboratories in remote tribal areas. Conclusions We conclude that the rapid, point-of-care testing device HemoTypeSC test is suitable for population and newborn screening for the HbS phenotype.

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