Correlation between the plasma level of von willebrand factor and the severity of sickle cell disease in Sudanese patients

Background: Sickle cell anaemia is a congenital hemolytic disorder caused by mutation in the β-globin gene at position 6 with replacement of glutamic acid by valine, which results in structural change in β-chain of haemoglobin. Homozygous patients suffer from hemolytic anaemia and other serious complications. The underline pathology of much of these complications is the recurrent occurrence of vasoocclusion due to microthrombi formation resulting in organs ischemia. In this study we investigated the role of vWF as a determinant of sickle cell disease severity through its contribution to the formation of such microthrombi. Patients and methods: Seventy Sudanese patients, homozygous for sickle haemoglobin were investigated in this study, they are 35 females and 35 males, the mean of their ages is 6.8 years. 34 patients presented during vasoocclusive crisis and 36 presented in steady state. The clinical disease severity was determined using two different scoring system, and vWF antigen level in the plasma was estimated by using ELISA technique. Results: Statistical analysis for the correlation between severity score and vWF level in the plasma (in steady state) revealed strong positive association in the couple of scoring systems (P = 0.008) and (P = 0.009) (Paerson correlation). Conclusion: Severity of sickle cell anaemia increases with elevation of vWF level in the plasma in the steady state. This is due to contribution of vWF to the formation of microthombi through platelet activation. Platelet count in turn affects vWF level, which is elevated with a high platelet count. Elevation of vWF and platelet count are associated with a hypercoagulable state in sickle cell anaemia