Table 3.

Loss of Nuclear Immunoreactivity for αABC Correlates with β-Catenin Mutations

	β-Catenin mutation	No β-catenin mutation	Totals
C Terminus +/αABC + (concordant pattern)	7	32	39
C Terminus +/αABC loss (discordant pattern)	13	1	14
Totals	20	33	53

Fisher’s exact test, P < 0.001.

Fifty-three tumors showing a nuclear immunoreactivity for C terminus β-catenin antibodies in a fraction of cells greater than 10% were probed with αABC antibody. Among 14 tumors showing a discordant pattern with C terminus β-catenin antibodies versus αABC (C terminus +/αABC loss), 13 carried mutation of β-catenin. Among the cases showing a concordant pattern of reactivity for C terminus β-catenin antibodies and αABC (C terminus +/αABC +, 39 cases), only 7 carried mutations. These mutations corresponded to D32Y, D32G, and S33F aminoacid substitutions (see Table 4 ▶ ).