The network of associations between death, clinical complications, and laboratory findings in sickle cell disease. The arc (arrow) direction specifies the conditional probability tables that are sufficient to compute the overall distribution. Colored in red are the nodes that alone are sufficient to predict the risk for death (severity score). Nodes in blue are associated with predictive nodes in red. For example, the Hb genotype is associated with several laboratory variables including WBC and LDH and thus modulates disease severity indirectly through these nodes. See Tables 3,4. ACS indicates acute chest syndrome; AVN, avascular necrosis; BUN/creatinine, ratio of BUN to creatinine; Sys BP, systolic blood pressure; Hb, total hemoglobin concentration; %HbF, percentage of fetal hemoglobin; WBC, leukocyte count; Hb genotype, sickle cell anemia, sickle cell anemia-α thalassemia, HbSC disease.