C-FMS POINT MUTATIONS IN ACUTE MYELOID-LEUKEMIA - FACT OR FICTION

Point mutations in codons 12,13, and 61 of N-ras have consistently been reported in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) using a variety of techniques. Recently mutations in codons 301 and 969 of c-fms, preferentially involving TAT-to-TGT at codon 969, have also been identified in these disorders by allele specific oligonucleotide (ASO) hybridization. We have developed allele specific restriction analysis (ASRA) protocols for the detection of point mutations in the critical codons of these genes. ASRA involves enzymatic digestion of polymerase chain reaction (PCR)-induced restriction sites which are specific for normal but not mutant alleles. A total of 11 N-ras mutations were observed in 10 out of 46 AML patients, consistent with the reported frequency of N-ras mutations when alternative techniques of comparable sensitivity are used. In contrast, c-fms point mutations were not detected in a similar number of patients with AML, including 39 studied for mutations in both N-ras and c-fms, and this difference is statistically significant (p < 0.003). A more sensitive technique (ASRA + ASO hybridization) also failed to detect TAT-to-TGT substitutions at codon 969 in a subgroup of M4-AML patients considered to be at greatest risk of harboring c-fms mutations. This study suggests that c-fms mutations at codons 301 and 969 are not important in the pathogenesis of AML in the vast majority of patients.