Collaborative Stage

Note 1: JAK2 is a gene mutation that increases susceptibility to several Myeloproliferative neoplasms (MPNs). Testing for the JAK2 mutation is done on whole blood. Nearly all people with polycythemia vera and about half of those with essential thrombocythemia and primary myelofibrosis have the mutation. When JAK2 is positive the MPN is definitely reportable, however JAK2 itself does not specify which MPN is present. Other diagnostic tests are required to determine the specific histology.
Note 2: JAK 2 is used primarily for the following histologies: Polycythemia Vera, Essential Thrombocytopenia and Primary Myelofibrosis. Its usage continues to increase and may be used for other histologies in the future. Record JAK-2 for any Heme-Retic disease even if it is not one of the histologies noted.
Note 3: If JAK-2 test result is positive, NOS, use code 850.

Code	Description
000	JAK-2 test result stated as negative
010	JAK2 test performed, positive for mutation V617F in exon 14
020	JAK2 test performed, positive for mutation of exon 12
800	JAK2 test performed, positive for other specified mutation
810	JAK2 test performed, positive for more than one mutation
850	JAK2 test performed, positive NOS; specific mutation(s) not stated
888	OBSOLETE DATA CONVERTED V0200 See code 988: Not applicable for this schema
988	Not applicable: Information not collected for this case (May include cases converted from code 888 used in CSv1 for "Not applicable" or when the item was not collected. If this item is required to derive T, N, M, or any stage, use of code 988 may result in an error.)
997	Test ordered, results not in chart
998	Test not done
999	Unknown Insufficient information Not documented in patient record

CS Site-Specific Factor 1
JAK-2 (also known as Janus Kinase 2 and JAK 2 Exon 12)