title: Relative role of APC and MUTYH mutations in the pathogenesis of familial adenomatous polyposis.
abstract: OBJECTIVE
  Familial adenomatous polyposis (FAP) is an interesting model for the study of colorectal tumour. Two genes contribute to the FAP phenotype - APC and MUTYH - but their relative role is still undefined. The objective of this study was to evaluate the contribution of the two genes to the pathogenesis of FAP by means of a series of FAP families.
  
  
  METHODS
  Sixty-one unrelated families with a diagnosis of FAP and a total of 187 affected individuals were evaluated. After extracting DNA, APC and MUTYH genes were sequenced.
  
  
  RESULTS
  In the whole series of patients, colectomy with ileorectal anastomosis was the most frequent surgery, although the number of patients treated by total proctocolectomy and ileoanal anastomosis was increasing. Duodenal and jejunal-ileal adenomas were present in more than half of the patients. Constitutional mutations were detected in 37 of the 45 families (82.2%); there were 33 families with APC and 4 with MUTYH alterations. Age at onset of polyposis and age at surgery were 10-15 years delayed for carriers of MUTYH mutations; cancer at diagnosis was frequent, and extracolonic manifestations were diagnosed in the majority of MUTYH-positive families. MUTYH-associated polyposis showed the horizontal transmission expected for recessive inheritance (at variance with the dominant pattern seen with APC mutations).
  
  
  CONCLUSIONS
  At least two genes are associated with the FAP phenotype. APC mutations account for the majority of cases, while MUTYH mutations can be observed in 10% of patients. There are few but definite differences between APC- and MUTYH-associated FAP, such as age at diagnosis and pattern of transmission.
authors: Department of Internal Medicine, University of Modena and Reggio Emilia, Modena, Italy.
authors: Annalisa
authors: A
authors: Pezzi
authors: Luca
authors: L
authors: Roncucci
authors: Piero
authors: P
authors: Benatti
authors: Romano
authors: R
authors: Sassatelli
authors: Liliana
authors: L
authors: Varesco
authors: Carmela
authors: C
authors: Di Gregorio
authors: Tiziana
authors: T
authors: Venesio
authors: Monica
authors: M
authors: Pedroni
authors: Stefania
authors: S
authors: Maffei
authors: Luca
authors: L
authors: Reggiani Bonetti
authors: Enrica
authors: E
authors: Borsi
authors: Maurizio
authors: M
authors: Ferrari
authors: Pietro
authors: P
authors: Martella
authors: Giuseppina
authors: G
authors: Rossi
authors: Maurizio
authors: M
authors: Ponz De Leon
mesh_terms: D011125:Adenomatous Polyposis Coli / Q000235:genetics / Q000473:pathology / Q000601:surgery; D000328:Adult; D017668:Age of Onset; D016009:Chi-Square Distribution; D045647:DNA Glycosylases / Q000235:genetics*; D005260:Female; D017491:Genes, APC; D020022:Genetic Predisposition to Disease; D006801:Humans; D007558:Italy; D008297:Male; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D012307:Risk Factors; D018709:Statistics, Nonparametric
chemical_list: D045647:DNA Glycosylases; C061738:mutY adenine glycosylase