paroxysmal nocturnal haemoglobinuria

Last edited 05/2021 and last reviewed 04/2022

Paroxysmal nocturnal haemoglobinuria is an acquired clonal, benign, haematopoietic stem cell disorder which results in the formation of defective red cells, white cells and platelets. It is characterised by intravascular haemolysis and frequent venous thrombosis or bleeding.

It is caused by a mutation in an X-linked gene involved in the formation of membrane phosphatidyl inositol anchors. The membranes of these cells are deficient in those proteins normally anchored to the cell through a phosphatidyl inositol linkage, including complement deactivating factors.

PNH is a very rare disorder and should be suspected in confusing cases of haemolytic anaemia.

About 4 decades ago 10-year survival for this condition was only 50 percent

  • however, in the last 15 years, advances in treatment such as the development of eculizumab have improved survival to more than 75 percent (1)


  • Schrezenmeier H, Muus P, Socié G, Szer J, Urbano-Ispizua A, Maciejewski JP, Brodsky RA, Bessler M, Kanakura Y, Rosse W, Khursigara G, Bedrosian C, Hillmen P. Baseline characteristics and disease burden in patients in the International Paroxysmal Nocturnal Hemoglobinuria Registry. Haematologica. 2014 May;99(5):922-9.