STUDIES IN SICKLE CELL ANEMIA<subtitle>Inheritance Factor, Including Effect of Interaction of Genes for Sicklemia and Thalassemia</subtitle>

Abstract

THE HEREDITARY nature of the sickling of erythrocytes of certain persons has been recognized and accepted for many years. The exact pathogenesis of the genetic pattern, however, has been the source of controversy. Earlier investigators¹recognized no genetic difference between sickle cell disease and the asymptomatic trait (sicklemia). They regarded both conditions as being due to a single dominant gene which in some persons produced active disease and in others only an asymptomatic trait. More recently, Neel²and Beet³have taken issue with the older hypothesis and have presented an alternative concept. According to these workers, the asymptomatic sickle cell trait is due to a gene which is represented but once in the patient's genetic system (heterozygous state), whereas active sickle cell disease appears when the gene occurs twice (homozygous state). Moreover, the earlier investigators often found the sickling phenomenon lacking in the blood of one parent