IDH1 WT and R132H mutation testing
In June 2016 the World Health Organization introduced new guidelines for the classification of brain tumors, specifically recommending the addition of molecular testing (1). At the top of the list for glioma stratification is testing for mutations in Isocitrate Dehydrogenase (IDH1 and IDH2), which have been shown to cause the Glioma CpG Island Methylator Phenotype (G-CIMP, 2). Certain mutations in these enzymes cause a gain of function which leads to a DNA hypermethylation phenotype that correlates with increased survival.
G-CIMP is caused approximately 90% of the time by the R132H mutation in IDH2. Therefore, because most DNA methylation detection technologies perform poorly on FFPE tissues for multi-gene DNA methylation profiling, as is required to definitely establish G-CIMP. Consequently, most researchers now analyze for the primary IDH1 and IDH2 mutations or sequence both genes and infer G-CIMP from that result. Our GliomaSTRAT assay will analyze for both the DNA methylation profile to definitely establish G-CIMP and MGMT methylation, as well as the primary glioma-genic mutation, IDH1 R132H. All biomarkers can be analyzed in a single assay (3).
However, for those wishing a rapid test for the IDH1 Wildtype and R132H alleles without sequencing, we offer a CAPS based test. CAPS reactions for the IDH1 R132H mutation were performed with a promoter-primer forming a mismatch at the site of the mutation.
(1) The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary. Acta Neuropatholgica, June 2016, volume 131, Issue 6, pp803-820.
(2) Noushmehr H, Weisenberger DJ, Diefes K et al. Identification of a CpG island methylator phenotype that defines a distinct subgroup of glioma. Cancer Cell 17(5), 510–522 (2010).
(3) McCarthy et al. (2016) MethylMeter®: bisulfite-free quantitative and sensitive DNA methylation profiling and mutation detection in FFPE samples. Epigenomics 8(6), 747-765.
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