title: Clinical and molecular features of attenuated adenomatous polyposis in northern Italy.
abstract: 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.
authors.affiliation: Dipartimento di Medicina Interna, Università di Modena e Reggio Emilia, Modena, Italy.
authors.forename: M Ponz
authors.initials: MP
authors.lastname: de Leon
authors.forename: E D L
authors.initials: ED
authors.lastname: Urso
authors.forename: S
authors.initials: S
authors.lastname: Pucciarelli
authors.forename: M
authors.initials: M
authors.lastname: Agostini
authors.forename: D
authors.initials: D
authors.lastname: Nitti
authors.forename: L
authors.initials: L
authors.lastname: Roncucci
authors.forename: P
authors.initials: P
authors.lastname: Benatti
authors.forename: M
authors.initials: M
authors.lastname: Pedroni
authors.forename: S
authors.initials: S
authors.lastname: Kaleci
authors.forename: A
authors.initials: A
authors.lastname: Balsamo
authors.forename: C
authors.initials: C
authors.lastname: Laudi
authors.forename: C
authors.initials: C
authors.lastname: Di Gregorio
authors.forename: A
authors.initials: A
authors.lastname: Viel
authors.forename: G
authors.initials: G
authors.lastname: Rossi
authors.forename: T
authors.initials: T
authors.lastname: Venesio
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D045647:DNA Glycosylases / Q000235:genetics*; D005260:Female; D005736:Gardner Syndrome / Q000235:genetics* / Q000473:pathology*; D017491:Genes, APC; D005838:Genotype; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010641:Phenotype; D018709:Statistics, Nonparametric; D047368:Tumor Burden / Q000235:genetics; D055815:Young Adult
chemical_list: D045647:DNA Glycosylases; C061738:mutY adenine glycosylase