Different expressivity of two adjacent mutations of the APC gene

Silvano Presciuttini, Viviana Gismondi, Edoardo Scarcello, Paola Sala, Francesco D'Elia, Carlo Rossetti, Cristina Caroti-Ghelli, Francesco Molina, Joanna Groden, Franco Mosca, Lucio Bertario, Liliana Varesco

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Aims and background: The phenotypic expression of different APC mutations in familial adenomatous polyposis (FAP) is variable: two to three variants of the disease have been defined based on the severity of colonic manifestations. Age of onset and number of polypectomies per person-year of post-surgical follow-up were compared in two FAP families with very close mutation sites in the APC gene, in order to ascertain mutation-specific variation of expressivity. Families and APC mutations: Family A (5 patients) carried a newly characterized mutation, a four bp deletion at codon 843. Family B (5 patients) carried a previously identified mutation at codon 835. Results: Mean age of onset was 49.7 years in family A and 30.5 years in family B; number of polypectomies per person-year of follow-up was 1.05 for family A and 10.1 for family B (P <0.001). Conclusions: There is significant variation of expressivity (allelic heterogeneity) in FAP between two mutations separated by only eight codons, located at the 5' extremity of APC gene exon 15.

Original languageEnglish
Pages (from-to)28-31
Number of pages4
Issue number1
Publication statusPublished - Jan 1999


  • APC mutations
  • FAP
  • Genotype-phenotype

ASJC Scopus subject areas

  • Cancer Research

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    Presciuttini, S., Gismondi, V., Scarcello, E., Sala, P., D'Elia, F., Rossetti, C., Caroti-Ghelli, C., Molina, F., Groden, J., Mosca, F., Bertario, L., & Varesco, L. (1999). Different expressivity of two adjacent mutations of the APC gene. Tumori, 85(1), 28-31.