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

Abstract

BackgroundIn sickle cell disease, the quantification of Hb A2 is important for the differential diagnosis between sickle cell anemia (Hb SS) and Hb S/β0-thalassemia.ObjectiveTo determine Hb A2 levels as quantified by high performance liquid chromatography in patients with sickle cell anemia (Hb SS) and with the SC hemoglobinopathy, with or without concomitant alpha thalassemia.MethodsThis is a retrospective study of 242 children aged between two and six years with diagnoses of Hb SS or Hb SC. The hemoglobin was evaluated using high performance liquid chromatography and alpha thalassemia [3.7 kb deletion (−α3.7)] was detected by polymerase chain reaction. Patients were classified as homozygous (−α3.7/−α3.7), heterozygous (−α3.7/α), or homozygous wild-type. Analysis of variance was used to compare the mean Hb A2 values between the alpha thalassemia groups.ResultsThe mean (± standard deviation) Hb A2 concentrations in the Hb SS group (n = 135) was 3.68 ± 0.65%. The mean values for individuals with Hb SS and heterozygous (n = 28) or homozygous for alpha thalassemia (n = 3) were 3.98 ± 0.64% and 4.73 ± 0.25%, respectively. The mean Hb A2 of all the Hb SC patients (n = 107) was 4.01 ± 0.507 with 4.29 ± 0.41% and 4.91 ± 0.22% in individuals heterozygous (n = 23) and homozygous for alpha thalassemia (n = 7), respectively. All patients homozygous for alpha thalassemia had Hb A2 levels above 3.5%. However, Hb A2 values above 5.2% were seen in patients with Hb SS and Hb SC, independently of alpha thalassemia.ConclusionHb A2 levels are elevated in patients with Hb S or Hb C, and are directly influenced by the alpha thalassemia genotypes.

Knowledge of professional healthcare providers about sickle cell disease: Impact of a distance education course

“…It predominantly affects the Black population and presents clinical manifestations within the first years of life with repercussions on morbidity and mortality 1, 2. Despite technological and scientific advances to improve the prognosis of sickle cell disease, its management persists as a challenge for professional healthcare providers, since it involves complex aspects of diagnosis, treatment and prevention of complications 3, 4, 5…”

The importance of hemoglobin A2 determination

“…There lies the importance of the paper entitled “Hemoglobin A 2 values quantified by high performance liquid chromatography in patients with sickle cell disease, and the influence of the presence of alpha-thalassemia” written by Fonseca et al and published in this edition of the Revista Brasileira de Hematologia e Hemoterapia. 22 The authors demonstrate that Hb A 2 was overestimated not only in individuals with Hb S but also in patients with Hb C, and that the Hb A 2 level was influenced by the genotype of α-Thal.…”

Techniques for the Detection of Sickle Cell Disease: A Review

“…The most popular methods for detecting these diseases are the full count of blood cells, Hb electrophoresis, and high-performance liquid chromatography (HPLC). These methods are considered the gold standard in the diagnosis of SCD [ 12 ].…”