Hemophilia is an X-linked recessive disorder in which affected individuals do not produce certain clotting factors. This results in copious bleeding after injuries. People with hemophilia A lack Factor VIII, people with hemophilia B lack Factor IX, for example. Patients with sickle cell anemia experience significant pain with dehydration and stress due to sickling of the red blood cells. Patients with polycythemia vera are generally asymptomatic but have an elevated hematocrit generally found with routine lab draws. Iron-deficiency anemia presents with weakness and fatigue but not excessive bleeding.