Harr Hematology Practice Test

Sickle cell trait is a condition where an individual inherits one normal hemoglobin gene (Hgb A) and one sickle hemoglobin gene (Hgb S). As a result, individuals with sickle cell trait typically have a mixture of normal hemoglobin (Hgb A) and elevated levels of Hgb S, but the predominant form is Hgb A. In patients with sickle cell trait, approximately 60% to 70% of hemoglobin is Hgb A, while about 20% to 30% is Hgb S. The presence of Hgb A allows for normal oxygen transport and function, which is why these individuals generally do not experience the severe symptoms associated with sickle cell disease, where sickle hemoglobin predominates and leads to various complications. Other forms of hemoglobin, such as Hgb F (fetal hemoglobin) and Hgb A2, are present in smaller amounts and have limited relevance in the context of sickle cell trait. Hgb F is produced during fetal development and tends to decrease after birth, while Hgb A2 is usually present at low levels in adults and does not significantly influence the hemoglobin profile in sickle cell trait.