Prevalent in parts of Asia and Medit
Patients have only one working gene for alpha globin, and make less than the usual amount of alpha globin chains.
Deletion of or mutations in three alpha-chain genes lead to hemoglobin H disease.
Ranges from a mild to severe chronic hemolytic anemia.
Most frequently results from an absence of three of the four Alpha-globulin genes.
This hemoglobin variant is primarily present throughout Southeast Asia, the Medit
Because of population migration from southeast Asia the incidence has increased significantly in the United States.
Hemoglobin H migrates at a fast rate at an alkaline pH during hemoglobin electrophoresis.
Patients at risk for developing severe anemia requiring urgent blood transfusions, especially during times of infection, fever, or pregnancy.
Patients may have hepatomegaly, splenomegaly, cholelithiasis, iron overload, growth retardation in children and, rarely, hydrops fetalis in utero.
The α-thalassemias are caused by deletions and nondeletional mutations affecting the two adjacent α-globin genes, α1 and α2, on chromosome 16p13.3, resulting in reduced or absent α-globin chain synthesis.
In hemoglobin H disease, 3 of the 4 alpha globin genes are either deleted or rendered functionally inactive through mutation.
α-thalassemia is the decreased production of α 2 -globin or α 1 -globin gene products
α-globin is a subunit essential for both fetal and adult hemoglobin.
Reduced α-globin production disrupts the ratio of globin chains.
The hemoglobin is unstable and is often associated mild to moderate anemia.
Infections or fever can make the anemia worse.
In California the incidence of hemoglobin H disease is about 1 in 15,000 births, or about 35-40 cases per year.
Compound heterozygosity for α-thalassemia, which is caused by the deletion of one-α-globin gene.
Carrier rates approach 70% in some areas of the world.
Hemoglobin H-Constant Spring disease, which is a more severe form of this disorder and can cause more severe anemia.
Hemoglobin H-Constant Spring disease produces a longer than usual alpha globin chain and causes the hemoglobin to be even more unstable than in hemoglobin H disease.
Laboratory results are similar to those with iron deficiency except that the red blood cell count and RDW are greater andv the MCV is usually lower.
Peripheral blood smear exhibits more targeting, anisocytosis, poikilocytosis, and polychromasia than in patients with iron deficiency.
The reticulocyte can is generally between five and 10% but may be within normal range.