Open AccessGenotyping concordance in DNA extracted from formalin‐fixed paraffin embedded (FFPE) breast tumor and whole blood for pharmacogenetic analyses
Author(s) -
Hertz Daniel L.,
Kidwell Kelley M.,
Thibert Jacklyn N.,
Gersch Christina,
Regan Meredith M.,
Skaar Todd C.,
Henry N. Lynn,
Hayes Daniel F.,
Van Poznak Catherine H.,
Rae James M.
Publication year - 2015
Publication title -
molecular oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.332
H-Index - 88
eISSN - 1878-0261
pISSN - 1574-7891
DOI - 10.1016/j.molonc.2015.07.002
Subject(s) - genotyping , concordance , single nucleotide polymorphism , genotype , molecular inversion probe , pharmacogenetics , snp , biology , breast cancer , snp genotyping , snp array , microbiology and biotechnology , genetics , cancer , gene
Background Cancer pharmacogenetic studies use archival tumor samples as a DNA source when germline DNA is unavailable. Genotyping DNA from formalin‐fixed paraffin embedded tumors (FFPE‐T) may be inaccurate due to FFPE storage, genetic aberrations, and/or insufficient DNA extraction. Our objective was to assess the extent and source of genotyping inaccuracy from FFPE‐T DNA and demonstrate analytical validity of FFPE‐T genotyping of candidate single nucleotide polymorphisms (SNPs) for pharmacogenetic analyses. Methods Cancer pharmacogenetics SNPs were genotyped by Sequenom MassARRAYs in DNA harvested from matched FFPE‐T, FFPE lymph node (FFPE‐LN), and whole blood leukocyte samples obtained from breast cancer patients. No‐ and discordant‐call rates were calculated for each tissue type and SNP. Analytical validity was defined as any SNP with <5% discordance between FFPE‐T and blood and <10% discordance plus no‐calls. Results Matched samples from 114 patients were genotyped for 247 SNPs. No‐call rate in FFPE‐T was greater than FFPE‐LN and blood (4.3% vs. 3.0% vs. 0.5%, p < 0.001). Discordant‐call rate between FFPE‐T and blood was very low, but greater than that between FFPE‐LN and blood (1.1% vs. 0.3%, p < 0.001). Samples with heterozygous genotypes were more likely to be no‐ or discordantly‐called in either tissue (p < 0.001). Analytical validity of FFPE‐T genotyping was demonstrated for 218 (88%) SNPs. Conclusions No‐ and discordant‐call rates were below concerning thresholds, confirming that most SNPs can be accurately genotyped from FFPE‐T on our Sequenom platform. FFPE‐T is a viable DNA source for prospective–retrospective pharmacogenetic analyses of clinical trial cohorts.