No JAK2 won’t get negative , treatment is to avoid the complications. This can be a spontaneous mutation that caused trouble in JAK2, such spontaneous changes won’t be transmitted and may not cause risk in family line . But if you are having family history , then yes it can be heritable- it’s an autosomal dominant transmission - so 50 % children of one diseased parent may harbour the disease . You can consult me with your family tree or history if you want to discuss this further