KRAS/BRAF mutation is associated with poor prognosis but is not a predictive biomarker for irinotecan or oxaliplatin. There is no evidence that patients with KRAS/BRAF mutated tumors are less likely to benefit from these standard chemotherapy agents.

For the Mutation Detection 2003 Special IssueScreening for deletions of all or part of genes poses a challenge in the diagnostic laboratory. Numerous methods are available for detecting deletions of a few base pairs or very large deletions, but difficulties arise in detecting deletions of a few kilobases. Two new techniques have recently been described that allow detection of such midsize deletions by simultaneously screening for the loss or duplication of up to 40 target sequences. These are the multiplex amplification and probe hybridization (MAPH) and the multiplex ligation-dependent probe amplification (MLPA). Both rely on sequence-specific probe hybridization to genomic DNA, followed by amplification of the hybridized probe, and semi-quantitative analysis of the resulting PCR products. The relative peak heights or band intensities from each target indicate their initial concentration. The two techniques differ in the ease with which probes can be generated in house, and the labor intensity of performing the assay.