title: K-ras mutation in colorectal carcinomas from singapore.
abstract: 54 sporadic colorectal cancers were analyzed for aberrations in the K-ras oncogene. DNA was extracted from frozen tissues obtained from surgical resection and analyzed for mutations in codons 12, 13 and 61 of the K-ras oncogene using single strand conformation polymorphism analysis (SSCP) and direct sequencing. Point mutations in the K-ras oncogene were found in 26/54 (48%) cases, all of which resulted in amino acid substitutions. No other types of mutations (e.g. insertions or deletions) were found. 4 of the mutations were at codon 12, 22 in codon 13 and only 1 was a codon 61 mutant. G-->A transitions were found to be predominant. A remarkable finding was the high preponderance of (13)Gly-(13)Ser mutations (54%). No correlation was observed between K-ras mutations and tumor location, Dukes' stage, differentiation levels, age or sex of the patient.
authors.affiliation: NATL UNIV SINGAPORE, DEPT COMMUNITY OCCUPAT & FAMILY MED, SINGAPORE 0511, SINGAPORE. NATL UNIV SINGAPORE, DEPT PATHOL, SINGAPORE 0511, SINGAPORE. NATL UNIV SINGAPORE, DEPT SURG, SINGAPORE 0511, SINGAPORE. NATL UNIV SINGAPORE, INST MOLEC & CELL BIOL, SINGAPORE 0511, SINGAPORE.
authors.forename: T
authors.initials: T
authors.lastname: Phang
authors.forename: C
authors.initials: C
authors.lastname: Shi
authors.forename: A
authors.initials: A
authors.lastname: Wee
authors.forename: S
authors.initials: S
authors.lastname: Ngoi
authors.forename: B
authors.initials: B
authors.lastname: Li
authors.forename: H
authors.initials: H
authors.lastname: Lee
authors.forename: C
authors.initials: C
authors.lastname: Ong