ADAMTS13 and acute chest syndrome: Although Demagny et al. did not find any significant reduction in ADAMTS13 antigen in patients with sickle cell compared to healthy controls, nor any difference in ADAMTS13 antigen between sickle cell patients in chronic steady state vs. those with veno-occlusive crises/acute chest syndrome [59], significant differences have been seen in vWF antigen, with increased levels in patients presenting with vaso-occlusive crisis [59,60,61] and elevated levels in more severe genotypes (HbSS or HBSβ0) [62], suggesting dysregulation of ADAMTS13-vWF axis.