A new phenotypic manifestation of familial adenomatous polyposis.

Familial adenomatous polyposis (FAP) is an autosomal dominant disease with hundreds of colorectal adenomas in teenagers and progression to colorectal cancer if colectomy is not performed. We investigated the association of two phenotypic manifestations-oral mucosal vascular density (OMVD) and oral mucosal reflectance (OMR)--with FAP and patients with multiple colorectal adenomas. Thirty-three patients with FAP from 29 unrelated pedigrees with APC gene mutation, 5 with multiple adenomas and no known gene mutations, and 50 population controls were evaluated for the two different manifestations utilizing a photographic/spectrophotometric system capturing images and reflectance at various wavelengths. Statistical analysis was performed with student t test and test performance characteristics were calculated. There were no significant differences in demographic variables between the FAP and control group. A significant difference in OMVD between FAP patients and controls was noted, P < 0.001. The sensitivity and specificity of oral mucosal vascular density for FAP was 91 and 90%, respectively. No association between this phenotypic manifestation and age or gender was found. All 5 patient with multiple polyps were positive for OMVD and the value was significantly higher than controls, P = 0.002. No significant difference was noted in OMR between the two patient groups and controls. OMVD is a new phenotypic manifestation in patients with FAP and also may identify those with multiple adenomas without known gene mutation.