ABSENCE OF MUTATIONS IN THE RET GENE IN ACUTE MYELOID-LEUKEMIA

Expression of the tyrosine kinase receptor RET has previously been det ected in normal hematopoietic cells, and especially in cells of the my eloid lineage. Furthermore, RET was shown to be differentially express ed in acute myeloid leukemia (AML), a disease characterized by excessi ve cell growth and aberrant maturation of cells, with the highest leve ls of expression in leukemias with monocytic differentiation. RET is k nown to be expressed in cells from the excretory system and from the d eveloping central and peripheral nervous system. Both activating and i nactivating aberrations in the RET gene have been detected in disorder s derived from these tissues. To investigate whether the differential expression is a primary defect in AML, the presence of RET alterations was scanned by Southern blot analysis on DNA of blasts obtained from 17 AML patients. However, no RET gene aberrations were found. Subseque ntly, denaturing gradient gel electrophoresis (DGGE) analysis was perf ormed on the DNA. of blasts from ten selected cases. All five variants detected turned out to represent neutral DNA polymorphisms, including a novel polymorphism in exon 14. Since we were unable to detect mutat ions of RET in AML, it is unlikely that it plays an important role in leukemogenesis.