Thalassemia is a blood disorder of genetic origin that results from the interaction of thalassemia genes and those genes associated with abnormal hemoglobins. Heterozygous thalassemia or thalassemia minor is the less serious form of the disorder and is generally without symptoms. Homozygous thalassemia or thalassemia major is the more serious form of the disorder and if untreated can lead to massive splenomegaly and death by 5 years of age. Thalassemia major also is referred to as Cooley’s anemia or Mediterranean anemia due to its high prevalence in Mediterranean and Middle Eastern countries (e.g., Cyprus, Greece, Turkey, and Italy) and descendants from these areas. Other regions where thalassemia major may be found include Southeast Asia and Africa. With increased mobility and marriage between ethnic groups, the prevalence of thalassemia major has decreased considerably over time; with geographic differences in prevalence, no single prevalence rate is cited. Although prevalence of the major form is of increasing rarity, individuals with thalassemia minor are carriers for the major form and should engage in genetic counseling prior to having children.
The homozygous form of deficient beta chain synthesis, which presents during childhood. This inherited blood disorder most commonly affects people of Mediterranean, Middle Eastern, Indian, Asian, and Southeast Asian descent. Malaria is endemic in these areas, and the thalassemia trait (carrier status that is generally asymptomatic) may provide protection against malaria. When both parents have the trait and pass it on to a child (25% chance in each pregnancy), the child develops the disorder. The different forms of thalassemia vary in severity, but each affects the body’s ability to produce a specific type of hemoglobin. The most severe form is B thalassemia major (Cooley’s anemia), which prevents or greatly reduces the body’s ability to produce “adult” hemoglobin (HbA). Clinically thalassemia is characterized by fatigue, splenomegaly, severe anemia, enlargement of the heart, mild jaundice, leg ulcers, and cholelithiasis. When untreated, bone marrow expands as the body attempts to increase blood cell formation, causes thickening of the cranial bones, and increases cheekbone eminences.