Sickle Cell Trait (Hemoglobin AS)
This patient has sickle cell trait (Hb AS), a benign carrier state that requires no treatment but warrants genetic counseling. 1, 2
Diagnosis
The hemoglobin electrophoresis pattern definitively establishes sickle cell trait:
- Hgb A 56.7% - Normal adult hemoglobin predominates
- Hgb S 38.8% - Sickle hemoglobin present at typical carrier levels (35-45%)
- Hgb A2 3.2% - Normal range (2-3.5%)
- Hgb F <1% - Normal adult level
- Hgb C <5% - Essentially absent 1
This pattern is characteristic of heterozygous inheritance of one normal β-globin gene and one sickle β-globin gene. The Hgb S percentage of approximately 40% is pathognomonic for sickle cell trait, distinguishing it from sickle cell disease (Hgb SS) where Hgb S would be >90% with no Hgb A present. 3
Clinical Significance and Management
Sickle cell trait is a benign condition with normal life expectancy and no routine treatment required. 1
Key management points:
- No hematologic intervention needed - Patients are asymptomatic with normal hematologic parameters 4
- Genetic counseling is mandatory - Family studies should be performed to identify other carriers and provide reproductive counseling 1, 2
- Reproductive risk assessment - If both partners carry sickle cell trait, there is a 25% risk of sickle cell disease (Hgb SS) in offspring, 50% risk of trait, and 25% chance of normal hemoglobin 2
Critical Pitfalls to Avoid
Do not confuse sickle cell trait with sickle cell disease or compound heterozygous states (such as Hgb SC disease or Hgb S/β-thalassemia), which require active management. The presence of >50% Hgb A confirms this is simple trait. 5, 3
Never skip family studies - This is essential for genetic counseling and family planning, particularly for identifying at-risk couples before conception. 1, 2
Do not use HbA1c for diabetes monitoring in patients with hemoglobinopathies unless using assays validated for use with variant hemoglobins, as standard assays may give inaccurate results. 1
Avoid misdiagnosis - The electrophoretic pattern must be carefully interpreted, as some rare variants (such as Hgb G-Philadelphia) can migrate similarly to Hgb S and create confusion. 5
Rare Clinical Considerations
While sickle cell trait is benign, counsel patients about extremely rare complications:
- Hematuria (from renal papillary necrosis)
- Splenic infarction at extreme altitude (>10,000 feet)
- Exertional rhabdomyolysis under extreme physical stress with dehydration 1
These complications are sufficiently rare that they do not warrant activity restrictions in daily life.