What is Paroxysmal Nocturnal Haemoglobinuria (PNH)?

The medical information provided on this website is by way of general guidance only. You should always contact your clinician for medical advice and do not rely upon the information provided here.


Paroxysmal nocturnal haemoglobinuria (PNH) is a rare disease affecting between approximately one and two people in every one million and affects both men and women at different ages. PNH is an ‘acquired’ genetic disease, so it cannot be inherited and patients are usually diagnosed in young adulthood.

PNH is a bone marrow failure disorder where abnormal blood cells can emerge from the bone marrow lacking multiple GPI- anchored proteins as a result of a genetic defect (mutation) in the “PIGA” gene. Absence of these proteins leave the blood cells unprotected against a series of complex reactions called “complement activation” which is part of the body’s normal immune response to fight infections. As a result, the red blood cells are destroyed (haemolysis) which is the main cause of PNH symptoms and complications.

PNH is often diagnosed with aplastic anaemia although patients can have one without the other. Treatment for aplastic anaemia is different from PNH and will depend on whether it is inherited or acquired.

Not everyone who has PNH is affected by it in the same way. Some people may have no symptoms and others may have many as well as other complications.

It is possible for PNH to disappear however this is not very common.

There is no cure yet for PNH, however there are successful treatments which can alleviate the symptoms.