alpha thalassemia major - أطلس مختبرات العرب

This is alpha thalassemia major. There have been two major variations of alpha thalassemia arise in human history. One variation, most prevalent in Southeast Asia, is known as alpha thalassemia 1. In this variant, two alpha globin genes are deleted on one chromosome 16. The other variant, known as alpha thalassemia 2, is most common in Africa and the Mediterranean region, and differs in that a single alpha globin gene is missing from one chromosome 16. Alpha thalassemia 1, with alpha globin gene deletions on a single chromosome 16, can give rise to alpha thalassemia major in the homozygous state, when both chromosomes are affected. Affected persons become anemic in utero, because even fetal hemoglobin cannot be produced, and severe hydrops fetalis results, which leads to stillbirth, or death soon after birth from pulmonary hypoplasia or cardiac failure. Hemoglobin electrophoresis will reveal affected fetuses or neonates to have about 80% hemoglobin Bart's (a tetramer of gamma chains) and about 20% hemoglobin Portland (or sometimes hemoglobin Gower 1) normally present only in embryonic life in the first trimester. RBC's that contain mostly hemoglobin Bart's have marked anisocytosis and poikilocytosis, and there is expansion of erythropoiesis with many immature RBC's in the peripheral blood, as evidenced by polychromasia, nucleated RBC's and even erythroblasts as shown here.