PNH Screen

General Information

Requests

Please supply clinical details as this may impact upon the final report. Recent transfusion history should also be supplied – red cell analysis is not available on post transfusion samples. Please be aware that it may not be possible to provide results on patients who are severely neutropenic.

GENERAL INFORMATION

PNH is caused by a single point mutation in the PIG-A gene resulting in disruption of glycosylphophatidylinositol (GPI) synthesis and a deficiency in all GPI-anchored proteins. 

De Novo PNH is rare but small clones may be recognised in conditions such as myelodysplasia and MDS.

PNH screening is performed by multi-colour flow cytometry which provides a sensitive and reliable recognition of PNH clones by analysis of red cells, neutrophils and monocytes.

Assay performance:

The Lower limit of quantitation (LLOQ) is 0.01% for red cell and neutrophil analysis. Clones may be recognised below this level, but are not quantifiable (this will be indicated on the report). This sensitivity relies upon the ability to count sufficient cells. In patients who are severely neutropenic (<1.0 x 10⁹/L) this may not be achievable.

The ability to identify PNH red cells is limited in patients who have received a recent blood transfusion. In these patients, and in patients who are actively haemolysing, clone size may be underestimated or not recognised. The purpose of red cell analysis is largely to recognise PNH type II and III clones.