Analysis of RAS gene mutations in acute myeloid leukemia by polymerase chain reaction and oligonucleotide probes.

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Abstract
In vitro DNA amplification followed by oligonucleotide dot blot analysis were used to study RAS gene mutations in acute myeloid leukemia (AML). Fifty-two presentation AML DNAs were screened for mutation in codons 12, 13, and 61 of NRAS and in codons 12 and 61 of KRAS and HRAS. Fourteen (27%) contained mutations-all in NRAS and predominantly in codon 12. The most common amino acid substitution identified was of glycine by aspartic acid at codon 12 (7/18), with a G .fwdarw. A transition being the most common base change (11/18). No particular correlation was observed between disease subtype and the incidence or type of NRAS mutation. In DNA samples from four patients, 2 NRAS mutations were found to coexist. NIH 3T3 focus-formation assays revealed that in each case the mutations were present in different NRAS alleles. We also report the absence of a mutated RAS gene in relapse DNAs of four patients in which a RAS oncogene had been detected at presentation. These observations suggest that RAS mutations arise as part of the evolution of neoplastic transformation.