HemeRetic

Note 1: Janus Kinase 2 (JAK2, JAK 2)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.
Note 2: JAK2 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 JAK2 for any hematopoietic/reticuloendothelial disease even if it is not one of these three specific histologies.
Note 3: If JAK2 test result is positive, NOS, use code 850.

Code	Description
000	JAK-2 result stated as negative
010	JAK2 positive for mutation V617F in exon 14
020	JAK2 positive for mutation of exon 12
800	JAK2 positive for other specified mutation
810	JAK2 positive for more than one mutation
850	JAK2 positive NOS; specific mutation(s) not stated
888	OBSOLETE DATA CONVERTED V0200 See code 988 Not applicable for this site
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 (test not ordered and not performed)
999	Unknown or no information Not documented in patient record

CS Site-Specific Factor 1JAK2 (also known as Janus Kinase 2 and JAK2 Exon 12)