Group of hemoglobin synthesis disorder caused by mutations or deletions in at least 1 of the 4 alpha-globin genes, leading to variably impaired alpha-globin chain production, with accumulation of the now excess and unpaired beta-globin chains. Most are asymptomatic, may present with fatigue, dizziness, shortness of breath, jaundice, hypersplenism, symptoms of gallstone, growth retardation in child, mild dysmorphic facial features (Maxillary hypertrophy, frontal bossing, and prominence of malar eminences), and extra medullary hematopoiesis. Antenatal diagnosis (CVS at 10—12 week, amniocentesis, fetal blood sampling after 18 weeks of gestation).