Paroxysmal Nocturnal Hemoglobinuria (PNH) is a rare disease affecting 1-4 people per 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, leucopenia, 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 because of the high morbidity associated with PNH, it is necessary to establish an assay able to detect and diagnose PNH. Flow cytometery provides the best methodology for detection of PNH clones and it is both more sensitive and specific than current assays used such as Ham and Sucrose Hemolysis test. In addition, PNH tests are mail out, therefore, there exists potential revenue and cost savings if Baylor Scott and White is able to perform the assay in-house. A multiparameter flow cytometric assay will be modified that will be capable of monitoring and diagnosing PNH clones; thus improving the patient’s likelihood of survival and prognosis.
Paroxysmal Nocturnal Hemoglobinuria (PNH) is a hemolytic anemia that is a 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 which are present on blood cells. The gene encodes for the protein glycosyltransferase which is an integral component in the creation of the GPI anchors present on blood cells (RBC’s) . GPI proteins are necessary in keeping proteins attached to the surface membrane of cells derived from hematopoiesis such as red blood cells, white blood cells, and platelets. The mutation in the PIG-A gene results in a stop codon, which causes a truncated version of glycosyltransferase rendering it functionless. The lack of glycosyltransferase prevents the transfer of N-acetyl glucosamine from UPD N-acetyl glucosamine to endoplasmic reticulum phosphatidylinositol preventing the formation of GPI linked proteins. GPI anchors are essential components in anchoring proteins that regulate the complement system and prevent unnecessary cell death. Several proteins that require GPI anchors are decay accelerating factor (CD 55) and membrane inhibitor of reactive lysis/protectin (CD59) respectively present on RBC’s. Decay accelerating factor (DAF) disrupts C3 convertase formation, and membrane inhibitor of reactive lysis (MIRL) prevents C9 from binding thus stops the membrane attack complex assembly3. In addition, CD66b which is may be responsible for signal transduction pathways and activation of neutrophils is affected by the lack of GPI anchors . Although the mutation arises in the hematopoietic stem cell, RBC’s experience lysis more readily than any other blood cell.
PNH can be further...