From OMIMAlpha-thalassemia is one of the most common hemoglobin genetic abnormalities and is caused by the reduced or absent production of the alpha-globin chains. Four clinical conditions of increased severity are recognized: the silent carrier state (clinically and hematologically normal); thalassemia trait (microcytosis, hypochromia, and mild anemia); hemoglobin H (HbH) disease (613978; moderate to severe microcytic, hypochromic, hemolytic anemia, mild jaundice, moderate hepatosplenomegaly); and Hb Bart hydrops fetalis syndrome (severe anemia, generalized edema, ascites, marked hepatosplenomegaly, skeletal and cardiac malformations, usually death in utero) (summary by Galanello and Cao, 2011).
http://www.omim.org/entry/604131 From MedlinePlus GeneticsAlpha thalassemia is a blood disorder that reduces the production of hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen to cells throughout the body.
In people with the characteristic features of alpha thalassemia, a reduction in the amount of hemoglobin prevents enough oxygen from reaching the body's tissues. Affected individuals also have a shortage of red blood cells (anemia), which can cause pale skin, weakness, fatigue, and more serious complications.
Two types of alpha thalassemia can cause health problems. The more severe type is known as hemoglobin Bart hydrops fetalis syndrome, which is also called Hb Bart syndrome or alpha thalassemia major. The milder form is called HbH disease.
Hb Bart syndrome is characterized by hydrops fetalis, a condition in which excess fluid builds up in the body before birth. Additional signs and symptoms can include severe anemia, an enlarged liver and spleen (hepatosplenomegaly), heart defects, and abnormalities of the urinary system or genitalia. Without treatment, most babies with this condition are stillborn or die soon after birth because of these serious health problems. Hb Bart syndrome can also cause serious complications for women during pregnancy, including dangerously high blood pressure with swelling (preeclampsia), premature delivery, and abnormal bleeding.
HbH disease causes mild to moderate anemia, hepatosplenomegaly, and yellowing of the eyes and skin (jaundice). The features of HbH disease usually appear in early childhood, and affected individuals typically live into adulthood.
https://medlineplus.gov/genetics/condition/alpha-thalassemia