GSTM1 and susceptibility to pneumonia measurement: Acute pain lasting >2 h and requiring care at a medical facilityACS: new pulmonary infiltrate with pneumonia-like symptoms, requiring O2 and/or blood transfusionHepatic sequestration: Increase liver size with RUQ pain, abnormal LFTs, drop in Hb ≥2 g/dLSplenic sequestration: an enlarged spleen and an acute decrease in Hb of ≥2 g/dLPriapism lasting >2 h and requiring a visit to a medical facilitySevere VOE defined as VOE requiring 24h of management in hospital or observation unit OR 2 visits to ER/day unit in 2 days with both needing IV treatment