Knowledge Check • The Blood Project

True or false: JAK2 V617F mutation is specific for polycythemia vera.

a

True

b

False

The mutation also occurs in other myeloproliferative neoplasms, though at lower frequency compared with polycythemia vera. For example, in essential thrombocythemia (ET) and primary myelofibrosis (PMF), the JAK2 V617F mutation frequency is estimated at 50% to 60%. The mutation can occur rarely in other hematologic malignancies such as myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), MDS/myeloproliferative neoplasm (MPN) overlap syndrome, and in half of the cases of refractory anemia with ringed sideroblasts associated with marked thrombocytosis.

True or false: JAK2 V617F mutation is sensitive for polycythemia vera.

a

True

The mutation occurs in over 95% of patients with polycythemia vera.

b

False

Sort the diseases according to whether they or not they are myeloproliferative neoplasms (MPN):

Chronic eosinophilic leukemia, NOS

Acute myelogenous leukemia

Mastocytosis

Polycythemia vera

Chronic neutrophilic leukemia

Myelodysplastic syndrome

Chronic myelogenous leukemia

Primary myelofibrosis

Essential thrombocythemia

MPN

Not MPN

Which of the following statement(s) is/are correct:

a

JAK2 V617F is a loss-of-function mutation

b

JAK2 V617F is a gain-of-function mutation

c

JAK2 V617F occurs in the pseudokinase domain of JAK2

Also called the JH2 domain.

d

JAK2 is a receptor tyrosine kinase

No, it is a non-receptor tyrosine kinase (i.e., a signaling intermediate).

A reminder of the location of the V617F mutation in the JH2 (pseudokinase domain) of JAK2:

What exon is the V617F mutation located in?

Click for Answer

Exon 14

What is ruxolitinib?

Click for Answer

An oral JAK1/JAK2 kinase inhibitor, Food and Drug Administration (FDA)-approved for the treatment of primary myelofibrosis or polycythemia vera (PV) in adults who have had an inadequate response to or are intolerant of hydroxyurea.