The majority of patients with essential thrombocythemia, primary myelofibrosis and polycythemia vera have a somatic mutation in one of three sites. A myeloproliferative neoplasm that is negative for all 3 of these mutations is termed "triple negative".

Common somatic mutations that drive MPNs involve:

(1) exon 9 of CALR (calreticulin, chromosome 19p13.13)

(2) exon 10 of MPL (thrombopoietin receptor, chromosome 1p34.2)

(3) V617F of JAK2 (chromosome 9p24.1)


A patient negative for all 3 is termed "triple negative".


Methods that can be used to identify disease driving mutations in a triple-negative patient:

(1) whole exome sequencing (WES)

(2) Sanger sequencing


These methods have identfiied a wide variety of mutations indicating that this group is heterogeneous.


The presence of polyclonal hematopoiesis (absence of clonal hematopoiesis) may indicate a hereditary/familial myeloproliferative disorder.

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