A comparison of Direct sequencing, Pyrosequencing, High resolution melting analysis, TheraScreen DxS, and the K-ras StripAssay for detecting KRAS mutations in non small cell lung carcinomas

Table 1 Summary of the genotyping results obtained with the five tested methods in 131 NSCLC samples

DNA sample number	Direct sequencing	Pyrosequencing	TheraScreen DxS	K-ras StripAssay	HRM	Consensus
1	12Cys	12Cys	12Cys	12Cys	Mutation	12Cys
2	13Cys	13Cys	Wt	13Cys	Mutation	13Cys
3	12Cys	12Cys	12Val	Wt	Mutation	12Cys
4	12Asp	12Asp	12Asp	12Asp	Mutation	12Asp
5	12Cys	12Cys	12Cys	12Cys	Mutation	12Cys
6	12Cys	12Cys	12Cys	12Cys	Mutation	12Cys
7	Wt	12Cys	12Cys	12Cys	Mutation	12Cys
8	Wt	12Val	12Val	12Val	Mutation	12Val
9	Wt	12Cys	12Cys	12Cys	Mutation	12Cys
10	Wt	12Cys	12Cys	12Cys	Wt	12Cys
11	Wt	Wt	12Cys	12Cys	Wt	12Cys
12	Wt	Wt	12Cys	12Cys	Wt	12Cys
13	Wt	Wt	12Val	12Val	Wt	12Val
14	Wt	Wt	12Cys	12Cys	Wt	12Cys
15	Wt	Wt	12Cys	12Cys	Wt	12Cys
16	Wt	Wt	12Arg	13Cys	Inconclusive	Mutation
17	Wt	Wt	12Cys	12Cys	Mutation	12Cys
18	Wt	Wt	12Asp	13Asp	Not tested	Mutation
19	Wt	Wt	12Asp	Wt	Mutation	12Asp
20	Wt	Wt	12Cys	Wt	Not tested	Inconclusive
21	Wt	Wt	13Asp	Wt	Not tested	Inconclusive
22	Wt	Wt	Wt	12Cys	Mutation	12Cys
23	Wt	Wt	Wt	12Cys	Mutation	12Cys
24	Wt	Wt	Wt	12Arg	Wt	Wt
25	Wt	Wt	Wt	12Val	Wt	Wt
26	Wt	Wt	Wt	12Cys	Wt	Wt
27	Wt	Wt	Wt	13Cys	Wt	Wt
28	Wt	Wt	Wt	12Ala,13Cys	Wt	Wt
29	Wt	Wt	Wt	12Ser	Not tested	Inconclusive
30	Wt	Wt	Wt	12Ala	Wt	Wt
31	Wt	Wt	Wt	Wt	Mutation	Wt
32	Wt	Wt	Wt	Wt	Mutation	Wt
33 - 131	Wt (99 samples)	Wt (99 samples)	Wt (99 samples)	Wt (99 samples)	Wt (87 samples), 11-no DNA template, 1 –inconclusive sample.	Wt

The consensus result for a given sample was taken to be that obtained when the two CE-marked methods (K-ras StripAssay and TheraScreen DxS) were concordant with one-another (results that do not match this consensus are highlighted with a dark background). The detection of different types of mutation by different methods (e.g. in sample 3, p.Gly12Cys vs p.Gly12Val; in sample 16, p.Gly12Arg vs p.Gly13Cys; and in sample 18, p.Gly12Asp vs p.Gly13Asp) was not considered indicative of discrepancy because the precise identity of the mutation present is clinically irrelevant in this case (instances of type-of-mutation discordance are highlighted with a light background). In cases where the K-ras StripAssay and TheraScreen DxS kit generated inconsistent results, the sample was considered to be mutated only if one of the other three methods indicated the presence of a mutation. Thus, three samples (samples 20, 21, and 29) generated inconclusive results. Inconclusive results were excluded from further analysis.

ISSN: 1756-9966