5/2/2023 0 Comments Thalassemia minor![]() In addition, β-thalassemia mutations can be found in the compound heterozygous state with mutant hemoglobins. They often have moderate to severe boney abnormalities due to excessive expansion of bone marrow in the face of ineffective erythropoiesis. There is an increased propensity of these patients to become iron overloaded secondary to increased iron absorption and from chronic transfusions therefore these patients may require regular iron chelation therapy. ![]() Often patients with β-thalassemia will require either chronic transfusions to survive (thalassemia major) or may require intermittent transfusions at times of illness (thalassemia intermedia). The extent of anemia can vary depending on the nature of the mutations present in the β-globin genes (which determine whether or not any residual β-globin is produced), the extent of fetal (γ) hemoglobin production to compensate for globin chain imbalance, the presence of concomitant α-thalassemia that can reduced globin chain imbalance, and other unknown factors affecting severity. Patients who acquire two β-thalassemia mutations generally have a severe microcytic and hypochromic anemia. In contrast to α-thalassemia mutations, most β-thalassemia mutations are due to point mutations rather than deletions. Beta-thalassemiaĬarriers of β-thalassemia mutations (β-thalassemia trait) have microcytosis, hypochromia, a normal or increased number of red blood cells, and often will have an elevation of the minor adult hemoglobin, (HBA 2), along with a mild anemia in some cases. This condition is so-named because the fetal β-like globin chain (γ-globin) forms Hemoglobin Barts when assembled as a tetramer of four γ-globin chains. The extent of the disease depends on the types of mutations present.ĭeletion of all four α-globin genes is usually incompatible with a viable birth, and fetuses affected by such a condition have a severe form of hydrops fetalis, known as Barts hydrops. Those with three α-globin genes deleted have a condition known as HbH disease, which can be very variable in severity, but which often involves a moderate to severe anemia that can require regular transfusion therapy. Those with cis deletions of α-globin have a risk of transmitting severe forms of α-thalassemia to their children and therefore genetic counseling can be helpful in such cases. These patients are considered to have α-thalassemia trait. Patients may have two α-globin genes deleted on the same chromosome (in cis) or on different chromosome (in trans), in which case such individuals have microcytic red blood cell indices and hypochromia along with a mild anemia. When one α-globin gene is deleted, there is generally no consequence and it is difficult to distinguish between these individuals and those without such deletions. In the case of α-thalassemia, there are normally four α-globin genes present, with two located on each copy of chromosome 16. Patients who have thalassemia have an anemia associated with microcytosis (low MCV) and hypochromia (low MCH), although the extent of anemia can be highly variable. Are you sure your patient has thalassemia? What should you expect to find? There can also be significant morbidity from iron overload in the thalassemias both due to chronic transfusions and from increased absorption of iron in the setting of ineffective red blood cell production. Patients who acquire two mutations from their parents (homozygous state) can have a severe disease involving an anemia that may require intermittent or chronic transfusions. Carriers can have abnormal red blood cell indices indicated by a low mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH), abnormalities on hemoglobin analyses, and a mild anemia, but are generally clinically asymptomatic. ![]() If one acquires a single mutation of the globin genes (a heterozygous state) from the parents, then one is a carrier for thalassemia (described as thalassemia trait). The thalassemias generally are transmitted as simple Mendelian genetic diseases.
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