![]() The pathophysiology of PNH is the genetic mutation of Phosphatidylinositol glycan anchor biosynthesis, class A(PIG-A) gene on chromosome Xp22.1, whose gene product is necessary for the synthesis of glycosylphosphatidylinositol (GPI) anchors the reduction or deletion of the GPI anchor is the result of mutation of PIG-A gene, which leads to the deficiency of GPI-anchored proteins (GPI-APs) ( Figure 1) ( 5). Due to the low incidence rate of PNH, the disease may be ignored easily, which often leads to misdiagnoses and missed diagnoses. If not diagnosed or treated well, it can cause a 35% death rate within 5 years ( 4). ![]() According to a recent study, the incidence rate of PNH and aplastic anemia (AA)-PNH syndrome was about 0.35 cases per 100,000 people per year, and the overall prevalence rate was 3.81 per 100,000 ( 3). In 2007, the incidence of PNH was reported to be 1.59 per 100,000 people in the United Kingdom ( 2). It is a benign clonal disease, characterized by intravascular hemolysis, hemoglobinuria, venous thrombosis, and bone marrow failure ( 1). Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell (HSC) genetic mutation disease, causing defective erythrocyte membrane hemolysis. In this paper, we focus on how T lymphocytes are involved in immune escape hypothesis in the pathogenesis of PNH. Besides, HSCs from PIG-A-knockout mice do not show clonal expansion in bone marrow, so PIG-A mutation cannot explain the clonal advantage of the PNH clone and some additional factors are needed thus, in recent years, many scholars have put forward the theories of the second hit, and immune escape theory is one of them. PIG-A gene mutation could also be found in bone marrow hematopoietic stem cells (HSCs) of healthy people, but they have no growth advantage only the HSCs with PIG-A gene mutation in PNH patients have this advantage and expand. The deficiency of complement inhibitors causes chronic complement-mediated intravascular hemolysis of GPI-anchor-deficient erythrocyte. Its pathologic basis is the mutation of the PIG-A gene, whose product is necessary for the synthesis of glycosylphosphatidylinositol (GPI) anchors the mutation of PIG-A gene results in the reduction or deletion of the GPI anchor, which leads to the deficiency of GPI-anchored proteins (GPI-APs), such as CD55 and CD59, which are complement inhibitors. Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell genetic mutation disease that causes defective erythrocyte membrane hemolysis. ![]() Department of Hematology and Oncology, Tianjin Medical University General Hospital, Tianjin, China. ![]() Chenyuan Li † Xifeng Dong † Huaquan Wang Zonghong Shao * ![]()
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