Alpha-thalassemia

Symptoms

What are the main symptoms of alpha-thalassemia?

The symptoms of alpha-thalassemia are variable, according to the severity of disease. Alpha-thalassemia is caused by mutations in the HBA1 and/or HBA2 genes. We each have two copies of HBA1 and HBA2, for a total of four copies.

Babies with no working copies of the HBA1 or HBA2 genes have the most severe form, hemoglobin Bart syndrome. Symptoms begin prenatally and include swelling of the body, fluid surrounding the brain, heart and lungs, severe anemia, enlarged liver and spleen, heart defects and defects of the urinary and genital system. Death usually occurs in newborns. These pregnancies can be complicated by preeclampia (extreme hypertension), excessive amniotic fluid or reduced amniotic fluid, bleeding in the genital tract, and premature delivery.

The less severe form of alpha-thalassemia is called hemoglobin H disease. These individuals have one working copy of the HBA1 or HBA2 gene. Symptoms of this form vary from mild to more severe. Symptoms usually start by age one, but for some, symptoms do not begin until adulthood. Those with more severe symptoms can have anemia, enlarged spleen, gallstones, slowed growth and decreased bone density. 24% to 80% of these patients receive blood transfusions, and blood transfusions start between 0 and 3 years of age. Those with less severe symptoms are less like to receive blood transfusions, with 3% to 29% chance. The age at first blood transfusion is older, between 6 and 15 years of age. The anemia, enlarged spleen, gallstones, slowed growth and decreased bone density are more mild. People with hemoglobin H disease may experience bone changes of the face, such as enlargement of the upper jaw, protruding of the forehead and enlargement of the cheekbones. In very severe cases, infants have died prenatally or soon after birth. The cause of this extreme variability is unknown.

People with alpha-thalassemia trait have two working copies of HBA1 or HBA2 genes. They have mild anemia. Silent carriers have three working copies or HBA1 or HBA2 genes and do not experience symptoms.

During pregnancy, women with hemoglobin H may experience more severe anemia. In the third trimester, increased rate of premature labor, preeclampsia and congestive heart failure have been reported.

Origa, R., Moi, P., Galanello, R., & Cao, A. (2013). Alpha-Thalassemia. GeneReviews at GeneTests Medical Genetics Information Resource (database online). Copyright, University of Washington, Seattle. 1997-2013. Available at http://www.genetests.org. Accessed (2/29/2016).

Vichinsky, E. (2012). Advances in the treatment of alpha-thalassemia. Blood Reviews, S31-S34. http://www.sciencedirect.com/science/article/pii/S0268960X12700103

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