Treatment of Sickle Cell Anemia

Abstract

SICKLE cell anemia was described first by Herrick in 1910.1 Since then, surveys of Negroes in the United States have revealed the incidence of the symptomless sickle cell trait to be about 9% and incidence of sickle cell anemia to be about 2.25 per thousand.2 In the past decade sickle cell anemia has been the subject of many studies, which have contributed greatly to our understanding of many of the abnormalities that occur in the disease. Conclusions drawn from these studies form the basis for our current ideas of the pathogenesis of the disease. Since our present therapy is directed toward this aspect of the disease, the pathogenesis of sickle cell anemia will be reviewed briefly before treatment is discussed. It now seems well established that the sickling phenomenon is due to a gene which produces sickle cell anemia when it is present in the homozygous state and sickle cell trait when it occurs in the heterozygous state.* The erythrocytes in both conditions are abnormal and assume the characteristic "sickle shape" when the hemoglobin is in the reduced form.5 This characteristic of the cells has been shown to be due to hemoglobin that is different from the normal electrophoretically.f Erythrocytes in patients with sickle cell anemia contain only the abnormal "sickle cell" hemoglobin, while those of persons with the sickle cell trait contain a mixture of the abnormal "sickle cell" hemoglobin and normal hemoglobin. Studies of erythrocyte survival in vivo indicate that the increased hemolysis in sickle cell anemia is due to a defect in the erythrocytes, which have a survival time much shorter than normal, in contrast with those in sickle cell trait, which apparently have a normal life span.4; A hemolytic type of anemia occurs because hematopoiesis, although increased, is not able to compensate for the excessive erythrocyte destruc¬ tion. In many patients hemoglobin and erythrocyte levels remain essentially the same over a period of years because the life span of the red cells and the maximum compensatory effort that the bone marrow is able to make remain unchanged. § On occasions this balance is upset, and the anemia rapidly becomes much more severe, either as a result of increased hemolysis or as a consequence of the develop¬ ment of a temporary aplastic state in the bone marrow.15 Aside from the sickling property of the erythrocytes and the presence of anemia, probably the most charac¬ teristic feature of sickle cell anemia is the occurrence of sudden attacks of pain or other localized manifestations in almost any part of the body. These episodes appear to be explained by the capillary engorgement and areas of infarction that are found

Considerazioni su un caso di due Gemelle Monozigotiche affette da Anemia Drepanocitica

“…2) II fatto che le crisi si accompagnino quasi sempre o a infezioni (virali o batteriche) o a febbri non meglio identificate (10,25,27,33) o a crisi di aplasie midollari le quali, a loro volta, come avviene anche per le altre malattie emolitiche, frequentemente sono connesse a infezioni virali (34).…”