The PTEN T167A assay is also able to differentiate between no spiked-in copies and one, three or ten tumor copies (at p < 0.001 for all pairwise comparisons) in the presence of 105 copies and 2 × 105 copies of wild type DNA; the NRAS Q61L mutation is able to differentiate between no spiked-in copies and three or ten tumor copies (at p < 0.001 for all pairwise comparisons) in the presence of 105 copies and 2 × 105 copies of wild type DNA, but not between zero and one spiked-in copy (p > 0.05 for both 105 and 2 × 105 copies). The gene discussed is PTEN; the disease is neoplasm.