Clinical utility of routine MPL exon 10 analysis in the diagnosis of essential thrombocythaemia and primary myelofibrosis.
Approximately 50% of essential thrombocythaemia and primary myelo-fibrosis patients do not have a JAK2 V617F mutation. Up to 5% of these are reported to have a MPL exon 10 mutation but testing for MPL is not routine as there are multiple mutation types. The ability to routinely assess both JAK2 and MPL mutations would be beneficial in the differential diagnosis of unexplained thrombocytosis or myelofibrosis. We developed and applied a high resolution melt (HRM) assay, capable of detecting all known MPL mutations in a single analysis, for the detection of MPL exon 10 mutations. We assessed 175 ET and PMF patients, including 67 that were JAK2 V617F-negative by real time polymerase chain reaction (PCR). Overall, 19/175 (11%) patients had a MPL exon 10 mutation, of whom 16 were JAK2 V617F-negative (16/67; 24%). MPL mutation types were W515L (11), W515K (4), W515R (2) and W515A (1). One patient had both W515L and S505N MPL mutations and these were present in the same haemopoietic colonies. Real time PCR for JAK2 V617F analysis and HRM for MPL exon 10 status identified one or more clonal marker in 71% of patients. This combined genetic approach increases the sensitivity of meeting the World Health Organization diagnostic criteria for these myeloproliferative neoplasms.
Department of Haematology, Haemato-Oncology Diagnostic Service, Addenbrooke's Hospital, Cambridge, UK.
Elaine M
EM
Boyd
Anthony J
AJ
Bench
Andrea
A
Goday-Fernández
Shubha
S
Anand
Krishna J
KJ
Vaghela
Phillip
P
Beer
Mike A
MA
Scott
David
D
Bareford
Anthony R
AR
Green
Brian
B
Huntly
Wendy N
WN
Erber
D000465:Algorithms; D003937:Diagnosis, Differential; D005091:Exons; D005819:Genetic Markers; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D055728:Primary Myelofibrosis / Q000175:diagnosis* / Q000235:genetics; D053628:Receptors, Thrombopoietin / Q000235:genetics*; D013920:Thrombocythemia, Essential / Q000175:diagnosis* / Q000235:genetics; D044366:Transition Temperature
D005819:Genetic Markers; D053628:Receptors, Thrombopoietin; C082218:MPL protein, human; C507924:JAK2 protein, human; D053614:Janus Kinase 2