POINT MUTATIONS OF THE N-RAS GENE IN THE BLOOD-PLASMA DNA OF PATIENTSWITH MYELODYSPLASTIC SYNDROME OR ACUTE MYELOGENOUS LEUKEMIA

Oncogene mutations are frequently found in several tumour types and, a mong these, point mutations of the ras gene are particularly significa nt. A predominance of N-ras mutations has been found in the bone marro w DNA of patients with myelodysplatic syndrome (MDS) or acute myelogen ous leukaemia (AML). On the other hand, increased levels of plasma DNA have previously been observed in patients suffering from various mali gnant diseases. In the present work we have investigated, by polymeras e chain reaction (PCR), point mutations of the N-ras gene in the DNA o f plasma, blood cells and bone marrow of 10 patients suffering from AM L or MDS. The different ras mutations detected in five cases were alwa ys present in the plasma DNA while sometimes absent in the DNA of peri pheral blood cells or bone marrow. This indicates that a bone marrow b iopsy or aspiration does not necessarily contain all the malignant clo nes involved in the disease. Plasma could thus prove to be an easily a ccessible and useful material for detection and monitoring of myeloid disorders.