| Summary: | 碩士 === 國立臺灣大學 === 醫事技術研究所 === 83 === Paroxysomal nocturnal hemoglobinuria (PNH) is an acquired hemo-lytic anemia characterized clinically by current episodes of intravascullar hemolysis resulting hemoglobinuria. The disease, which is a stem cell disorder of a clonal nature, is associated with complication, such as venous thrombosis, bone marrow dys- plasia, and leukemic conversion. The hemolysis is a consequence of the abnormal sensitivity of the erythrocytes to complement-mediated lysis. It is well known that abnormal sensitivity is predominantly due to a deficiency in complement regulatory mem-brane proteins, that control the activity of both the C3 con-vertase and the membrane attack complex, such as CD55(DAF) and CD59(MIRF). CD55 and CD59 share the common biochemical feature of binding anchored to the cell by glycosyl phosphatidyl inositol (GPI) moiety. A defect in biosynthesis of the GPI-anchor results in deficiency of surface expression of CD55, CD59, and multiple proteins. Recent studies have shown that first interme-diate in the pathway of GPI-anchor synthesis is not formed in PNH cell line. By using expression cloning, the complementary DNA(called Phosphatidylinositol Glycan Class-A: PIG-A )that corrects the abnormality in GPI-anchor synthesis for PNH in all patient examined. We studied blood cell from 10 patient with PNH.The cell content of CD55 and CD59 was assayed by fluorescence-activated flowcytometry. In patient with PNH, CD55 expression was deficient in 32% to 85%, and CD59 in 33% to 92%. The genomic DNA of PIG-A was amplified by the polymerase chain reaction and analyzed by direct nucleotide sequencing. We found somatic mutations in PIG-A gene from two patients, LT and YHL. Form patient LT, two nucleo- tides were observed after codon 23 of the sample in the patient, in dicating that there was a G deletion before codon23. From patient YHL, two nucleotides were observed at codon 405 of the atient,indicating that there was a C to T mutation at codon 405.
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