Microcytosis is seen in -

Causes of microcytosis (MCV < 80fl) • Iron deficiency anemia • Thalassemia • Sideroblastic anemia • Anemia of chronic disease In Hb Barts, all the four a chain genes are deleted resulting in formation of Barts Hb. In Hb Lepore, there is nonhomologus fusion of b and d genes and forms an abnormal hemoglobin with total absence of normal b chain. It is one of the form of b thalassemia minor.