Patient description: The patients is a 25-year-old G1 P1 pregnant woman who is 24W3D gestational old who developed a sudden unset of fever and chills, accompany with nausea and vomiting. She also complains of dysuria, urgency and frequency. She also reports some severe pain in the flank. Her vital signs are: T = 39.7ºC, P = 117, R = 20, and BP = 113/74 mm Hg. Physical examination reveals tenderness on palpation of both costovertebral angles. She has no history of recurrent UTI prior to her pregnancy or any other underlying disease. The urine culture showed Gram-negative rod-shaped bacterial cells, leukocytes, and leukocyte casts. The blood culture is negative. A CBC shows Hb 12.9 g/dL, Hct 39%, MCV 76 fL, WBC count 14,120/µL.

Clinical trial eligibility criteria: eligible ages (years): 0.0-999.0,  Hemoglobinuria, Paroxysmal Screening Period: Individuals at least 18 years of age; Patients must have required at least 4 episodes of transfusions in the 12 months prior to Visit 1 for anemia or anemia-related symptoms; Presence of a GPI deficient red blood cell clone (type II cells) by flow cytometry of greater than or equal to 10%; Patients taking erythropoietin must be on a stable dose for 26 weeks prior to visit 1 and the dose must be expected to remain stable during the Observation Period and the Treatment Phase; Patients taking immunosuppressants must be on a stable dose for at least 26 weeks prior to Visit 1 and the dose must be expected to remain stable during the Observation period and the Treatment Phase; Patients taking corticosteroids must be on a stable dose for at least 4 weeks prior to Visit 1. The dose level may be decreased during the study as clinically appropriate. If the corticosteroids need to be increased, they may not be increased above the dose reported at Visit 1; Patients are allowed to take coumadin, but must be at a stable international normalized ratio (INR) level for 4 weeks prior to Visit 1 and are expected to maintain a stable INR level during the Observation Period and the Treatment Phase; Patients taking iron supplements or folic acid must be on a stable dose for 4 weeks prior to Visit 3 and be expected to remain stable during Observation Period and the Treatment Phase; Patients are allowed to take low molecular weight heparin, but must be on a stable dose for 4 weeks prior to Visit 1 and the dose must be expected to remain stable during Observation period and the Treatment Phase; Patient must be willing and able to give written informed consent; Patients must be vaccinated against N. meningitidis at Visit 1 or at least 14 days prior to Visit 3; Patient must avoid conception during the trial using a method that is most appropriate for their physical state and culture Observation Period: Documented LDH level greater than or equal to 1.5 x upper limit of normal (ULN) either at Visit 1 or during the Observation Period; Patients who have received one PRBC transfusion during the Observation Period at a hemoglobin value of less than or equal to 9 gm/dL with symptoms or at a hemoglobin value of less than or equal to 7 gm/dL without symptoms, and also within 1.5 gm/dL of the mean hemoglobin pre-transfusion value for the previous 12 months. This transfusion should be in accordance with that patient's individual transfusion hemoglobin algorithm, and occur within 48 hours of the hemoglobin sample that precipitated the transfusion; Platelet count greater than or equal to 100,000/mm(3) either at Visit 1 or during the Observation Period  Patients whose mean hemoglobin levels prior to transfusion over the previous 12 months is greater than 10.5 gm/dL; Absolute Neutrophil count less than or equal to 500/microL; Presence or suspicion of active bacterial infection, in the opinion of the Investigator, at Visit 3 or recurrent bacterial infections; Known or suspected hereditary complement deficiency; Participation in any other investigational drug trial or exposure to other investigational agent, device, or procedure within 30 days prior to Visit 1; Pregnant, breast-feeding, or intending to conceive during the course of the study, including the Post-treatment Phase; History of meningococcal disease; History of bone marrow transplantation; Any condition that, in the opinion of the Investigator, could increase the patient's risk by participating in the study or confound the outcome of the study