title: Acute myeloid leukemia: analysis of ras gene mutations and clonality defined by polymorphic X-linked loci.
abstract: In vitro DNA amplification and synthetic oligonucleotide hybridization was used to analyze 57 acute myelocytic leukemias (AML) for the presence of ras gene mutations. We demonstrated mutated alleles in 19% of primary AMLs (10/51) as well as in five of six secondary leukemias. Mutations occurred predominantly at N-ras codons 12, 13, or 61 (13 cases) and twice at Ki-ras codons 12 and 13. Ras gene mutations were preferentially associated with an M4 morphology according to the FAB (French-American-British) classification, but no particular correlation was observed with respect to clinical parameter (sex, age, course of disease) or immunophenotype and karyotype. Mutated ras alleles were absent in nine mutation-positive cases analyzed during remission. However, a more complex pattern emerged from the five patients analyzed in relapse exhibiting identical ras mutations in three cases, absence of a mutated allele in one patient, and acquisition of a N-ras mutation in yet another case, in which no mutation had been detected initially. Moreover, restriction fragment length polymorphisms (RFLP) of the X-chromosome genes hypoxanthine phosphoribosyl transferase (HPRT) and phosphoglycerate kinase (PGK) were studied in 19 of the AML patients. Nine cases (47%) were heterozygous for BglI or BamHI RFLPs at the PGK or HPRT loci, respectively, and therefore suitable for clonal analysis investigating X-chromosome inactivation. All of the patients exhibited a monoclonal leukemic cell population at presentation. In addition, five of seven cases studied in remission showed reemergence of a polyclonal pattern. However, two children exhibited persistence of monoclonal hematopoiesis despite complete clinical/hematological remission and a corresponding loss of a mutated ras allele in one of the patients. These data indicate the value of molecular genetic approaches for evaluation of the heterogeneous nature of remission and relapse in AML.
authors.affiliation: Department of Pediatrics II, University of Ulm, F.R.G.
authors.forename: C R
authors.initials: CR
authors.lastname: Bartram
authors.forename: W D
authors.initials: WD
authors.lastname: Ludwig
authors.forename: W
authors.initials: W
authors.lastname: Hiddemann
authors.forename: J
authors.initials: J
authors.lastname: Lyons
authors.forename: M
authors.initials: M
authors.lastname: Buschle
authors.forename: J
authors.initials: J
authors.lastname: Ritter
authors.forename: J
authors.initials: J
authors.lastname: Harbott
authors.forename: A
authors.initials: A
authors.lastname: Fröhlich
authors.forename: J W
authors.initials: JW
authors.lastname: Janssen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D011905:Genes, ras; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D015470:Leukemia, Myeloid, Acute / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010735:Phosphoglycerate Kinase / Q000235:genetics; D012150:Polymorphism, Restriction Fragment Length; D014960:X Chromosome
chemical_list: D007041:Hypoxanthine Phosphoribosyltransferase; D010735:Phosphoglycerate Kinase