Alpha-globin is made by four genes, two on each strand of chromosome 16. Alpha-Thalassemia results from decreased production of alpha-globin due to a deletion or mutation in one or more of the four alpha-globin gene copies. The more genes affected, the less alpha-globin produced. Hence resulting in four different types of alpha-thalassemia: · Silent Carrier State (one affected gene): causes no health problems because the lack of alpha-globin is so small that there is no anemia, but individuals can pass on the affected gene to their offspring. · Alpha Thalassemia Trait (two affected genes): patients with this condition have red blood cells that are microcytic, hypochromic, have decreased MCV, and have mild chronic anemia. · Hemoglobin H Disease (three affected genes): this condition can cause moderate to severe anemia, splenomegaly, bone deformities, and fatigue. · Alpha Thalassemia Major (also called hydrops fetalis, four affected genes): the most severe form of alpha thalassemia. No alpha globin is produced in this case, therefore, no Hb A or Hb F are produced. Most individuals with this condition die before or shortly after birth. This test can be used to detect the presence or absence of large deletions in the HBA1 or HBA2 gene in patients or their family members suspected of having alpha thalassemia or who are carriers of alpha globin deletions. It can also be used in the prenatal diagnosis of alpha thalassemia.
Collect in EDTA vacutainer tube. Avoid contamination with DNA of phlebotomist. Avoid haemolysed samples. Do not freeze samples. Send tube unopened.