All are seen in sickle cell anemia EXCEPT -

The terms "sickle cell crisis" or "sickling crisis" may be used to describe several independent acute conditions occurring in patients with SCD. SCD results in anaemia and crises that could be of many types including the vaso-occlusive crisis, aplastic crisis, sequestration crisis, haemolytic crisis, and others. Most episodes of sickle cell crises last between five and seven days. "Although infection, dehydration, and acidosis (all of which or sickling) can act as triggers, in most instances, no predisposing cause is identified." Ref Robbins 9/e pg 411