Use

JAK2 (9p24.1) break‑apart test by FISH is useful for detecting JAK2 rearrangements in eosinophilia workup. Eosinophilia is a common feature of the diseases that are recognized by the WHO category, Myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1, or with PCM1‑JAK2. For analysis of JAK2 mutations for suspected myeloproliferative neoplasms (MPN), consider JAK2 V617F Mutation Analysis with or without reflex to JAK2 Exon 12‑14 Mutation Analysis by molecular.