Thalassemia is a group of genetic blood disorders where the synthesis of one of the polypeptide chains that form hemoglobin is decreased, resulting in abnormal formation of hemoglobin and destruction of red blood cells, leading to anemia. There are 2 major types: alpha thalassemia occurs when genes related to alpha globin protein are missing or mutated, and beta thalassemia occurs when genetic defects affect beta globin protein production.

Common clinical features of alpha thalassemia include anemia with skin pallor, weakness, and fatigue.

The most severe form of alpha thalassemia is hemoglobin Bart hydrops fetalis (Hb Bart) syndrome. Hb Bart syndrome is characterized by hydrops fetalis, a condition where excess fluid builds in the body prior to birth, resulting in hepatosplenomegaly, cardiac abnormalities, and genitourinary defects. Most neonates with this form of thalassemia are stillborn or die shortly after birth. Maternal complications include preeclampsia, premature delivery, and abnormal bleeding.

Hemoglobin H (HbH) disease is another form of alpha thalassemia that causes mild-to-moderate anemia, hepatosplenomegaly, and jaundice. In some cases, patients may experience bone changes due to extra-medullary hematopoiesis such as jaw overgrowth or prominent forehead. Onset is typically in early childhood, and patients usually live into adulthood.

Alpha thalassemia occurs more frequently in residents of Southeast Asia, North Africa, India, Central Asia, the Middle East, and Mediterranean countries. Caused by HBA1 and HBA2 gene deletions, it has a complex inheritance pattern, and offspring may inherit if both parents are missing at least one alpha globin allele.

Treatment is dependent on the severity of disease.