Table 1.

Summary of epigenetic, genetic, and associated phenotypic alterations

Site and type of alteration	Percentage of tumors	No. tumors	Total tumors evaluated
APC gene
APC gene alteration identified	70.2	146	208
APC promoter hypermethylation	31.7	64	202
Mutation in APC mutation cluster region	62.0	129	208
Point mutation	—	87 (136)*	—
G-to-A transition	—	19 (25)*	—
C-to-T transition	—	30 (32)*
Frameshift mutation	—	57 (59)*	—
MGMT gene and MGMT expression
MGMT promoter hypermethylation	27.4	57	208
Loss of MGMT protein expression	24.5	51	208
Concordance of MGMT methylation status with MGMT protein expression status	82.7	172	208
hMLH1 gene and microsatellite instability
hMLH1 promoter hypermethylation†	9.2	19	207
Loss of hMLH1 protein expression	9.8	20	204
Concordance of hMLH1 methylation status with hMLH1 protein expression status	94.6	192	203
High levels of microsatellite instability (MSI-H)	10.6	22	208
Concordance of hMLH1 methylation status with MSI status	92.6	187	202
CpG island methylation of additional markers
Frequency of hypermethylation
P16 gene†	19.5	39	200
N33 gene	93.8	180	192
MINT1†	10.1	21	208
MINT2†	22.6	47	208
MINT25	28.3	51	180
MINT27	39.6	67	169
MINT31†	20.3	42	207
CIMP with three markers (≥ 60%)	10.1	21	208
KRAS proto-oncogene/BRAF gene
KRAS codon 12 or 13 mutation	39.2	80	204
KRAS codon 12 or 13 G-to-A transition	—	56	—
Codon 12a G-to-A	—	5	—
Codon 12b G-to-A	—	26	—
Codon 13b G-to-A	—	25	—
BRAF mutation	6.5	13	199
BRAF V600E nt 1799 T-to-A transversion	4.5	9	199
Discordant KRAS and BRAF V600E mutation status	100	9	9
P53 gene
Exon 5–8 mutation	55.2	112	203
G-to-A transition	—	40	—
C-to-T transition	—	31	—

^*Number in parenthesis is the number of APC mutations. The total number of APC mutations exceeds the number of tumors due to the occurrence of multiple mutations in 41 tumors. The total number of point mutations includes the number of G-to-A transition mutations.

^†Five markers used to define CIMP based on cluster analysis (see Fig. 2).