Alpha-thalassemia trait

Loss of two of the four α-globin genes (either both on one chromosome cis or one on each trans). Causes a mild hypochromic, microcytic anemia with no or minimal symptoms.

• By itself it causes minimal health issues (often only slight anemia), but cis deletion carriers (common in Asians) have significant risk of a child with Hb Bart's hydrops fetalis if the partner is also cis carrier. Often mistaken for iron deficiency; identifying it prevents unnecessary iron therapy.

• Mild microcytosis (MCV ~70–75) with normal or mildly low hemoglobin (often 11–13 g/dL). Patients are usually asymptomatic. Sometimes detected via newborn screening (transient 5–10% Hb Bart's at birth that disappears later).
• Labs: Iron studies normal. Electrophoresis typically normal (no significant changes in HbA2 or HbF). RBC count may be normal or slightly elevated. Blood smear may show slight hypochromia and occasional target cells.
• Often discovered in evaluation of a mild anemia that doesn't respond to iron. More common in individuals of African (trans deletions) or Southeast Asian (cis deletions) descent.

1. Differentiate from β-thalassemia trait: in α-thalassemia trait, HbA2 is normal (in β-trait, HbA2 is high). Family studies can help (Africans often have trans α-thalassemia, which generally poses less risk to offspring than cis).
2. Genetic testing is definitive if needed (DNA analysis for α-globin gene deletions), especially in prenatal context. If a patient is a cis deletion carrier, test the partner to assess hydrops risk.
3. No specific therapy required for the mild anemia. Avoid iron unless deficient. Ensure patients (especially those with cis mutations) understand the risk of hydrops fetalis in offspring if partner is also a carrier.

1. No treatment needed for anemia itself (it's very mild). Advise folate-rich diet or supplementation if any hemolysis (though significant hemolysis is not typical in trait).
2. Avoid unnecessary iron supplements (can cause overload). Monitor during pregnancy as anemia may slightly worsen; treat with transfusion only if absolutely needed (rare).
3. Key management is genetic counseling: if both parents have α-thalassemia trait (especially cis type), offer prenatal diagnosis (CVS or amniocentesis) to detect hydrops fetalis early.

• In African populations, α-thalassemia trait is often trans (α-/α-), which doesn't cause hydrops in offspring (child would just have trait). In Southeast Asians, trait is often cis (–/αα), so two cis carriers can have a hydrops baby.
• If microcytosis is present but electrophoresis is normal, think α-thalassemia trait (especially if iron is normal).
• On newborn screening, 5–15% Hb Bart's can be seen in α-thalassemia trait, but disappears after infancy as beta chains take over.

• Two potential cis-carrier parents (Southeast Asian descent) planning children — urgent need for genetic counseling and prenatal testing to prevent unrecognized hydrops fetalis.
• If a patient with trait shows unexpectedly severe anemia or hemolysis, look for an additional problem (e.g., coexistent iron deficiency or G6PD deficiency) — trait alone shouldn't cause severe anemia.

1. Microcytosis + normal iron + normal electrophoresis → suspect α-thalassemia trait.
2. If confirmation needed (e.g., for prenatal planning), do DNA analysis for α-globin gene deletions.
3. Identify if deletion is cis or trans (family/ethnic background helps): if cis, test partner. If both cis → offer invasive prenatal testing for each pregnancy.
4. Otherwise, routine care; monitor CBC periodically. Ensure appropriate counseling and avoid unwarranted iron therapy.

• An otherwise healthy 30-year-old African-American man has a mild microcytic anemia (Hb 12) with normal iron and normal electrophoresis → α-thalassemia trait (trans).
• A pregnant Southeast Asian woman is found to have microcytic anemia with normal iron and normal electrophoresis; her husband has the same → α-thalassemia trait (likely cis) in both, high risk of Hb Bart's hydrops fetalis.