t(X;17)(p11;q21) BCOR/RARA

	t(X;17)(p11;q12), G-banding.

Disease	A variant case of acute promyelocytic leukemia
Epidemiology	Very rare. One case has been reported.
Clinics	A bone marrow sample was markedly hypercellular, containing 83% promyelocytes. Coagulopathy was present with an increased prothrombin time, an activated partial thromboplastin time, decreased fibrinogen, and mildly increased fibrin/fibrinogen degradation products.
Cytology	Bone marrow promyelocytes were strongly positive for Sudan black B, myeloperoxidase staining and naphthol AS-D chloroacetate staining and negative for alpha-naphthyl butyrate staining. Flow cytometric analysis: HLA-DR-/CD13+/CD33+/CD56+.
	Rectangular cytoplasmic bodies and round inclusions are found in some of hypergranular promyelocytes. May-Giemsa staining.
Treatment	Conventional chemotherapy plus ATRA achieved complete remission, followed with consolidation therapies. However, 35 months after diagnosis, the patient relapsed and cord blood transplantation was performed with a myeloablative conditioning regimen. After engraftment was achieved, a bone marrow sample showed third CR. The patient demonstrated overt coagulopathy, sensitivity to ATRA, but resistance to arsenic trioxide.

	FISH analysis (Vysis LSI PML/RARA dual color, dual fusion translocation probe, Vysis; Downers Grove, IL). One of the RARA signals (green) is split. PML signals (red) are intact.

	Schematic diagram of RARA, BCOR and the BCOR-RARA fusion protein. The break point is indicated by the black line. Ankyrin repeats (ANK).
Transcript	BCOR cDNA (isoform b; reference NM_001123384) from exons 1 to 12 to be fused to RARA exon 3. Full length chimeric fusion transcripts spanning from the start codon to 4948 nt of BCOR cDNA fused to RARA cDNA from exon 3 to the stop codon. A reciprocal chimeric cDNA of RARA-BCOR was not detected.

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