FAP is caused by mutations in the APC gene and various genotype-phenotype relationships have been defined including reports that colorectal polyposis is less severe with mutations 5' to codon 157 and that the risk of desmoid tumours is high in FAP patients with APC gene mutations between codons 1444 and 1598.
The aim of this study was to assess the potential for APC gene transfer into fibroblasts in vitro and in vivo as a basis for consideration of gene therapy in the prevention or treatment of desmoid tumours.
An analysis was made of the association between development of desmoid and age at colectomy, family history of desmoids, gender, and APC mutation in FAP patients in the Registry (1980-2005) at Mount Sinai Hospital, Toronto, Ontario, Canada.
As predicted by the APC germline mutations among these patients, a high percentage (29%) of FAP-associated desmoids showed loss of the APC region at 5q22.2, which was infrequently (3%) seen among sporadic tumours.
The finding of low-frequency CTNNB1 mutation or APC loss in wild-type desmoids was validated in the remaining eight wild-type desmoids; directed miSeq identified low-frequency CTNNB1 mutation in four and comparative genomic hybridization identified APC loss in one.
FAP results from germline adenomatous polyposis coli (APC) gene mutations and desmoids arise following biallelic APC mutation, with one change usually occurring distal to the second beta-catenin binding/degradation repeat of the gene (3' to codon 1399).
Previous studies reported that CTNNB1 mutations were detected in 84% and that mutations of the APC gene were found in several cases of sporadic desmoid tumors lacking CTNNB1 mutations.
A similarity to abdominal fibromatoses (desmoids) in familial adenomatous polyposis and a cytogenetic study showing partial deletion of 5q in a subset of aggressive fibromatoses suggests that the adenomatous polyposis coli (APC) gene plays a role in its pathogenesis.
This study investigated the risk of desmoids in FAP, the relation between specific APC gene mutations and desmoid formation, and the clinical characteristics of FAP patients with desmoids.
These findings are compatible with the presence of a "second hit" inactivation of the APC gene and implicate this gene in the pathogenesis of desmoid tumors.
We report a familial adenomatous polyposis patient with a known truncating mutation on exon 15 of the APC gene who developed an invasive follicular thyroid cancer in addition to multiple intra-cranial and spinal desmoids.
Mutations in the APC gene contribute to development of sporadic desmoid tumors as well as to the hereditary tumors that usually accompany familial adenomatous polyposis (FAP).
In agreement with Knudson's 'two-hit' theory, the inactivation of the residual APC gene in FAP is a critical step in the development of both colorectal cancer and desmoids.
Multivariate analysis was performed, and hazard ratios (HR) calculated for variables including female gender, 3' APC mutation, surgical intervention for FAP (colectomy with ileo-rectal anastomosis or restorative proctocolectomy), age at surgery and family history (FH) of desmoids.
Genetic testing for germline mutations of the APC gene in patients with apparently sporadic desmoid tumors but a family history of colorectal carcinoma.
There is an increased risk for desmoid tumors in individuals with APC mutations between codons 543-713 and 1310-2011 when compared to a reference population.
This family report shows that a molecular analysis of the APC gene should be performed in familial desmoid tumors for accurate genetic counseling and follow-up.
The truncated APC gene retained 3 repeats in 88% (7/8) of FAP duodenal tumors, 100% (26/26) of gastric tumors retained 2 or 3 repeats and 83% (5/6) of desmoid tumors retained 2 repeats.