Status of the APC Gene in Familial and Sporadic Colorectal Tumours as Determined by Closely Flanking Markers

Using polymorphic close-flanking markers, allele deletion in the vicinity of APC was detected in the majority of sporadic colorectal cancers in a large unselected series. Deletion was due to interstitial deletion or mitotic recombination, but seldom to whole chromosome loss. Mitotic recombination affecting APC was associated with smaller tumours than interstitial deletion. Sporadic adenomas showed a slightly lesser frequency of allele loss, but no such loss was observed in 28 adenomas from 4 cases of familial polyposis.