Polycythemia vera: analysis of DNA from blood granulocytes using comparative genomic hybridization.

BACKGROUND AND OBJECTIVES The diagnosis of polycythemia vera (PV) is supported by the finding of an abnormal karyotype in patients with erythrocytosis. However, most PV patients have normal marrow cytogenetics at presentation and there is reluctance to use this test routinely. Comparative genomic hybridization (CGH) is a cytogenetic screening technique that analyzes interphase cells. This approach offers practical advantages over conventional cytogenetics and interphase fluorescence in-situ hybridization (IFISH). We have therefore evaluated the diagnostic utility of CGH applied to blood granulocytes in PV. DESIGN AND METHODS Blood granulocytes from 17 PV patients were analyzed using CGH and the results compared with those from previous conventional cytogenetics and IFISH studies. RESULTS Three patients had abnormal CGH profiles. One case had gain of 9p. This patient had normal IFISH results using a centromere-9 probe. The second case had complete gain of chromosomes 8 and 9 and the third had complete gain of chromosome 9, all confirmed by IFISH: Cytogenetics had not been performed in two of these cases and had failed in the third. Three cases with 20q deletion according to cytogenetics and/or IFISH, were normal by CGH. The remaining subjects were normal by all methods. INTERPRETATION AND CONCLUSIONS CGH analysis of blood granulocytes can detect the chromosome gains commonly observed in PV. However, CGH cannot be relied on to detect 20q deletions, which are the most frequent cytogenetic abnormality in PV. Thus, CGH has a role in the diagnosis and follow-up of PV patients, but must be used in conjunction with other methods.