Combined iPLEX and TaqMan assays to screen for 45 common mutations in Lynch syndrome and FAP patients

Mutations of genes associated with the mismatch repair mechanism and mutations of the APC gene are the most frequent causes of hereditary colorectal cancer. An iPLEX test combined with TaqMan genotyping assays was therefore developed to identify common recurrent mutations of those genes in the Polish population. We analyzed 349 DNA samples from 95 positive controls previously identified by sequencing and 254 unexamined individuals. The iPLEX test included two plexes, which comprised seven mutations of the APC gene and 29 mutations of three of the mismatch repair genes. TaqMan assays were designed for nine mutations not covered by the iPLEX assays: one mutation in the APC gene and eight mutations in the mismatch repair genes. Results were then verified independently by sequencing. Our combination method allowed detection of all recurrent mutations occurring in group of patients, followed by full analysis by DNA sequencing. With the exception of one false positive in the iPLEX test in the positive control group that could be assigned to contamination from neighboring wells rather than a detection error, given sufficient DNA concentration and quality, the designed iPLEX/TaqMan test had an accuracy of 100% for the designed assays. These results suggest that the combined iPLEX/TaqMan test is an outstanding tool for identification of recurrent mutations among hereditary colorectal cancer patients.