Adenomatous polyposis coli promoter abnormalities in familial adenomatous polyposis and gastric adenocarcinoma and proximal polyposis of the stomach

Table 1 Classification of familial adenomatous polyposis and gastric adenocarcinoma and proximal polyposis of the stomach associated with adenomatous polyposis coli promoter-region alterations

Class	Genetic alteration	Typical variants	Predominant phenotype	Gastric involvement	Colorectal involvement	Cancer risk
I	Promoter 1B-limited deletion	Large deletions in promoter 1B	Classical FAP	Absent-mild	Severe	High CRC risk
II-a	YY1 binding site SNV	c.-191T>C, c.-191T>G, c.-195A>C	GAPPS	Severe	Absent-mild	High GC risk
II-b	YY1 binding site SNV	c.-192A>T, c.-190G>A	Classical FAP	Absent-mild	Severe	Moderate CRC risk
II-c	YY1 binding site indel	c.-192_-191delATinsTAGCAAGGG	Mixed GAPPS and AFAP	Severe	Moderate	High GC and moderate CRC risks
III	Non-YY1 binding site SNV	c.-40G>A	AFAP	Absent	Moderate	Moderate CRC risk
IV	Large structural alteration	Chromothripsis and large upstream CNVs	Classical FAP or AFAP	Not available	Severe	Moderate CRC risk

FAP: Familial adenomatous polyposis; CRC: Colorectal cancer; YY1: Yin Yang 1; SNV: Single-nucleotide variant; GAPPS: Gastric adenocarcinoma and proximal polyposis of the stomach; GC: Gastric cancer; AFAP: Attenuated familial adenomatous polyposis; CNV: Copy number variation.