Table 3.

Association between the sites of the two APC mutations in sporadic colorectal tumors: By comparison with FAP (9), is allelic loss more common in sporadic tumors with a truncating mutation between codons 1,194 and 1,392 than in tumors with truncating mutations after codon 1,392?

	Sites and types of mutation		Total
	1,194–1,392	>1,392
LOH	18	16	34
No LOH	7	19	26
Total	25	35	60

As for Table 2, data are derived from the cell lines analyzed in this study and sporadic colorectal tumors in the APC Mutation Database, and only tumors with two hits identified are included. Numbers of tumors are shown, categorized according to their mutations, which are classified as (i) allelic loss (LOH) versus no loss (that is, an identified truncating mutation) and (ii) truncating mutations between codons 1,194 and 1,392 versus truncating mutations after codon 1,192. A problem in assessing these data is how to categorize tumors with one mutation between 1,194 and 1,392 and the other mutation after codon 1,392. We have taken an essentially conservative approach, which is to count these tumors twice in the table. Expected numbers of tumors (not shown) are then calculated on a multiplicative basis, assuming independence of the two hits. LOH is more strongly associated with tumors with truncating mutations between codons 1,194 and 1,392 (χ² = 4.10; df = 1; P < 0.05). If tumors with one mutation between 1,194 and 1,392 and the other mutation after codon 1,392 are counted once (that is, half in each category), the association is stronger (χ² = 4.53).