Abstract
The frequency and severity of the painful sickle cell crisis vary greatly among affected patients. Aside from a high level of Hb F(>20%) there is no established parameter which may modulate the clinical severity of the disease. In this paper we describe two groups of adult patients with homozygous SS and present their characteristics. The division into these two groups was on the basis of relatively low RBC deformability (≤37% of control) and high RBC deformability (>65% of control) in the steady state. None of the patients had α‐gene deletion and all had Hb F level Mild disease as far as painful crises are concerned, Increased number of Dense cells, and Decreased red cell Deformability. In addition these patients have high incidence of leg ulcers, have low incidence of urinary tract infection, and less mortality. Cellular factors seem to contribute to the incidence of painful crises.