Alpha-thalassemia

One or more genes coding the alpha-globin chain of Hg is deleted.
Blood smear: target cells; hypochromic, microcystic erythrocytes.

4 variants:
1) 3-4 N genes - no symptoms
2) 2 N genes -----mild anemia, decreased MCV
3) Hg H disease,only 1 N gene------severe hemolytic anemia, MCV<70, splenomegaly
4) hydrous fetalis, NO N genes, stillbirth