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Background: Attenuated familial adenomatous polyposis (AFAP) is characterized by the presence of 10-99 colorectal adenomas. The disease may be associated with mutations in either APC or MUTYH genes. We purposed to evaluate the contribution of adenomatous polyposis coli ( APC) and MutY homologue ( MUTYH) germline alterations to the AFAP phenotype and to identify genotype/phenotype correlations. Methods: During counselling for familial adenomatous polyposis (FAP), 91 probands (and 107 affected individuals) who met the criteria of AFAP were identified. Eighty-two families were screened for constitutional mutations of the APC and MUTYH genes. Results: MUTYH mutations were detected in 21 families (25.6 % of the 82 tested), and APC mutations in 7 (8.5 %). Overall, constitutional alterations were found in 34.1 % of the probands. Patients with APC mutations were younger at cancer onset and had a higher mean number of polyps (48.5 ± 33.0 in APC+ individuals vs. 35.7 ± 24.9 in MUTYH+ individuals, and 33.2 ± 18.4 in the 'no mutation' group). Clinical features rendered the 'no mutation' group closer to MUTYH+ than to the APC+ group. Colorectal cancer at diagnosis was detected in 40 % of AFAP individuals. Conclusions: AFAP is a new clinical entity with its frequency in the general population still undefined. The number of adenomas varies greatly, with an average of 30-40 lesions. The molecular basis of AFAP can be established in approximately 1/3 of the patients. Both MUTYH and APC genes are implicated in AFAP, though the role of MUTYH is of considerably greater relevance. [ABSTRACT FROM AUTHOR]

The use of computed tomographic colonography (CTC) as a screening test for colorectal cancer is being advocated with growing enthusiasm by physicians and the public as stronger evidence of its validity and limited invasiveness emerges from the literature. Because the approach to surveillance of colorectal cancer depends on an individual's degree of risk category, which depends on familial and personal histories, it seems logical that the diagnostic performance and cost efficacy of screening CTC may differ according to the characteristics of the target population. Although CTC seems a valid option in low- to average-risk populations, pending a careful assessment of its cost and estimates of its cost efficacy, there are some important issues that should be addressed when it comes to considering its use in high-risk patients. The expected larger number of induced colonoscopies and higher false-positive rates are likely to have a great influence on CTC costs, but if its implementation causes a dramatic increase in the number of patients willing to undergo screening, thanks to its acceptability, then the cost efficacy ratio may ultimately become competitive with all other screening strategies for colorectal cancer. We strongly feel that large and well-conducted trials are needed to clarify the role of CTC in screening patients at increased risk of developing colorectal cancer. [ABSTRACT FROM AUTHOR]