Patients with classic paroxysmal nocturnal hemoglobinuria (PNH) have clinical evidence of intravascular hemolysis typified by reticulocytosis, abnormally high concentration of serum lactate dehydrogenase, indirect bilirubin, and abnormally low concentration of serum haptoglobin. These symptoms are due to a lack of being able to carry out which of the following posttranslational modifications?

Question

Quizplus · Accepted Answer

Patients with PNH have a deficiency in the GPI anchor, which is a type of glipiated linkage, due to mutations in the PIGA gene. This deficiency leads to the absence of protective proteins on the surface of red blood cells, causing hemolysis.  Many membrane-associated glycoproteins belong to neither the peripheral nor the transmembrane class. These glycoproteins are tethered to the outer leaflet of the plasma membrane via a glycosylphosphatidylinositol linkage to their C-termini. This type of membrane attachment is referred to as a GPI linkage and the glycoproteins are termed glypiated proteins. One clinically important glypiated protein is the glycoprotein present on the surface of erythrocytes, that is, decay-accelerating factor (DAF; also known as CD55 = cluster of differentiation protein 55). The normal function of DAF is to prevent erythrocyte lysis by complement

Patients with Classic Paroxysmal Nocturnal Hemoglobinuria (PNH) Have Clinical Evidence