They form when there is a mutation in the Adenomatous Polyposis Coli gene or APC gene, which is a tumor suppressor gene that regulates cell growth.

当结肠腺瘤样息肉病（APC）基因突变时，结肠腺瘤往往会形成；APC基因是一种调控细胞增殖的抑癌基因。