BOTH PAROXYSMAL NOCTURNAL HEMOGLOBINURIA (PNH) TYPE II CELLS AND PNH TYPE III CELLS CAN ARISE FROM DIFFERENT POINT MUTATIONS INVOLVING THE SAME CODON OF THE PIG-A GENE

To the Editor: Paroxysmal nocturnal hemoglobinuria (PNH) is due to a somatic mutation of the PIG-A gene occurring in a hematopoietic stem cell. This results in a deficiency of all proteins that are normally attached to the cell membrane via a glycosyl phosphatidylinositol (GPI) anchor.[1][1] [2][2