Dear Editor,Inherited pericentric inversion of chromosome 9, the inv(9)(p11-q13), has been found in approximately 1–4% ofhumans without apparent phenotypic consequences [1, 2].Although inv(9)(p11-q13) has been regarded as a normalfamilial karyotype variant, it has also been associated withpredisposition to the development of solid tumors [3, 4] andacute biphenotypic (ABL) [5], lymphoblastic (ALL) [6],and myeloblastic (AML) [7] leukemias. Moreover, theinherited chromosomal abnormality has been associatedwith increased risk for acute leukemia (AL), delay inbone marrow (BM) recovery after chemotherapy for AL,and delay in engraftment after allogeneic hematopoieticstem cell transplantation (HSCT) from carriers of the inv(9) in some reports [5, 6, 8, 9] but not in others [7, 10–12]. Additionally, an acquired inv(9)(p11-q13) has beendescribed in a case of essential thrombocythemia (ET)[13], a case of AML, and a case of severe anemia due togastrointestinal bleeding [14]. Thus, the role of thechromosomal abnormality in hematological diseases, ifany, remains unclear. Herein, we report, after approvalfrom the local Ethics Committee, an inherited inv(9)(p11-q13) in a patient with transient pancytopenia and in apatient with polycythemia vera (PV) and discuss thesignificance of these findings.A 34-year-old previously healthy white man wasevaluated in our service in April 2005 because of a1-month history of headache. No abnormalities were foundat physical examination. Hematological data were asfollows: hemoglobin (Hb), 12.0 g/dl; white blood cell(WBC), 1.2×10