JAK2 is a member of the Janus kinase family.In 2013, two groups detected calreticulin mutations in a majority of JAK2-negative/MPL-negative patients with essential thrombocythemia and primary myelofibrosis, which makes CALR mutations the second most common in myeloproliferative neoplasms. All mutations (insertions or deletions) affected the last exon, generating a reading frame shift of the resulting protein, that creates a novel terminal peptide and causes a loss of endoplasmic reticulum KDEL retention signal. Diagnosis
The following revised diagnostic criteria for essential thrombocythemia were proposed in 2005. The diagnosis requires the presence of both A criteria together with B3 to B6, or of criterion A1 together with B1 to B6. The criteria are as follows:
A1. Platelet count > 400 × 103/µL for at least 2 months. A2. Acquired V617F JAK2 mutation present
B1. No cause for a reactive thrombocytosis
normal inflammatory indices
B2. No evidence of iron deficiency
stainable iron in the bone marrow or normal red cell mean corpuscular volume
B3. No evidence of polycythemia vera
hematocrit < midpoint of normal range or normal red cell mass in presence of normal iron stores
B4. No evidence of chronic myeloid leukemia
But the Philadelphia chromosome may be present in up to 10% of cases. Patients with the Philadelphia chromosome have a potential for the development of acute leukemia, especially acute lymphocytic leukemia. B5. No evidence of myelofibrosis
no collagen fibrosis and ≤ grade 2 reticulin fibrosis (using 0–4 scale)
B6. No evidence of a myelodysplastic syndrome
no significant dysplasia
no cytogenetic abnormalities suggestive of myelodysplasia

Treatment
Indications
Not all those affected will require treatment at presentation.
While most consumers find the taste of macrogol itself to be very mild and unobjectionable, the electrolytes contained in formulations for purging and cleansing give the solution an extremely salty and bitter taste.Polyethylene glycol-electrolyte solution is a prescription product sold under various brand names including Colyte, Gavilyte, Golytely, Nulytely, Moviprep, and Trilyte. Research
PEGylation
When attached to various biopharmaceutical medications (which are proteins), macrogol results in a slowed clearance of the carried protein from the blood. This makes for a longer-acting medicinal effect and reduces toxicity, and it allows for longer dosing intervals. It also reduces the proteins immunogenicity. Examples for PEGylated proteins include peginterferon alfa-2a and -2b, which are used to treat hepatitis C, pegfilgrastim, which is used to treat neutropenia, and pegloticase for the treatment of gout. Nerves and spinal cords
There is evidence demonstrating PEG-induced repair of specific nerve cells in animal models:

It has been shown that macrogol can improve healing of spinal injuries in dogs. One of the earlier findings is that macrogol can aid in nerve repair in earthworms. The subcutaneous injection of macrogol 2000 in guinea pigs after spinal cord injury leads to rapid recovery through molecular repair of nerve membranes. The effectiveness of this treatment to prevent paraplegia in humans after an accident is not known yet. Macrogol is being used in the repair of motor neurons damaged in crush or laceration incidents in vivo and in vitro. When coupled with melatonin, 75% of damaged sciatic nerves were rendered viable.