Alpha-thalassemia is an inherited condition that have defect in hemoglobin synthesis produces a hypochromic, microcytic anemia. Affected individuals have premature red blood cell destruction which can cause pale skin, weakness, fatigue, and more serious complications. Alpha-thalassemia is caused by decreased synthesis of alpha-globin chains. Four alpha-globin genes are normally present (2 on each chromosome 16). One, 2, 3, or 4 alpha-globin genes may be deleted or, less commonly, contain mutations. Deletions account for approximately 90% of disease-causing alleles in alpha thalassemia. The 7 most common including --SEA, --THAI, --FIL, --MED, -α3.7, -α4.2 and -α20.5 are tested by this assay. Less frequently, alpha-thalassemia results from single point mutations. The most common nondeletion mutation in Thailand is hemoglobin Constant Spring (HbCS) and hemoglobin Pakse (HbPS). Point mutations other than HbCS and HbPS are not detected by this assay.