Table 3.

Pre- and Post-test probabilities of being an MLH1 mutation carrier for three a priori risk groups

		*ACII	*BG & *1dMMR tumour	General population & *1dMMR tumour
Pre-test probability		60% (6)	10.5% (21–23)	4.0% (23–26)
Post-test normal MLH1 promoter region	True positive	85.5%	31.4%	14.0%
	False negative	12.6%	1.2%	0.4%
Post-test wt BRAF	True positive	74.9%	19.0%	7.7%
	False negative	17.5%	1.6%	0.6%
Post-test wt BRAF OR normal MLH1	True positive	71.6	18.5	7.7
	False negative	13.1	1.31	0.6
Post-test wt BRAF AND normal MLH1	True positive	86.9	33.5	15.5%
	False negative	22.9	2.3	0.8%

AC = Amsterdam criteria and BC = Bethesda guidelines

^*1dMMR tumour = MLH1 loss on immunohistochemistry or MSI-H