Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease affecting 1-4 people in a million. The median survival rate is 10-15 years, with 35% of patients diagnosed with PNH dying within five years3. PNH is characterized by thrombocytopenia, leukopenia and thrombosis. Paroxysmal nocturnal hemoglobinuria should be suspected when the patient has hemoglobinuria with a negative Coombs test, aplastic anemia, and myelodysplastic syndrome. PNH often goes undiagnosed, and due to the high morbidity associated with it, there is a need to establish a test that can detect and diagnose PNH. Flow cytometry provides the best methodology for the detection of PNH clones and is more sensitive and specific than currently used tests, such as the ham and sucrose hemolysis assay. Additionally, PNH tests are mailed, so there is potential revenue and cost savings if Baylor Scott and White are able to perform the test in-house. A multiparametric flow cytometric test will be modified that will be able to monitor and diagnose PNH clones; thus improving the probability of survival and prognosis of the patient. Paroxysmal nocturnal hemoglobinuria (PNH) is a hemolytic anemia that is the result of a somatic mutation in the hematopoietic stem cell that arises from the bone marrow. The somatic mutation occurs in the phosphatidylinositol glycan complementation group A (PIG-A) gene. PIG-A is responsible for the assembly and production of glycosylphosphatidylinositol (GPI) proteins found in blood cells. The gene encodes the protein glycosyltransferase which is an integral component in creating the GPI anchors present on blood cells (RBCs). GPI proteins are needed to keep the proteins attached to the center of the paper. Furthermore, compensation will be required to reduce the fluorescent crossover of each individual antibody. After determining the appropriate dilutions and determining the correct parameters, the analysis of patients will begin. The analysis will be completed on both PNH patients and normal patients. Since PNH is a rare malignancy, PNH positive samples will be ordered to evaluate and confirm that the correct parameters have been established and that the sensitivity for detection of PNH clones is acceptable. Data Analysis The data collected will evaluate the sensitivity of the test with known PNH positive specimens and determine whether the correct parameters for the detection of PNH clones have been established. Histograms and scatterplots will be included in the data analysis to analyze the different clinical outcomes associated with PNH and also to compare what a normal population looks like.