A family with attenuated familial adenomatous polyposis due to a mutation in the alternatively spliced region of APC exon 9

Hum Mutat. 1998;11(6):450-5. doi: 10.1002/(SICI)1098-1004(1998)11:6<450::AID-HUMU5>3.0.CO;2-P.


A family is presented with attenuated familial adenomatous polyposis of variable phenotype. The clinical features range from sparse right-sided polyposis and cancer in the proximal colon at the age of 34 to pan-colonic polyposis and cancer at the age of 68. Rectal sparing is common to all affected members. Heteroduplex analysis detected bands of altered mobility in exon 9 of the APC gene in all affected family members. Subsequently, a frameshift mutation was found in the alternatively spliced region of exon 9 at codon 398 which resulted in a stop signal 4 codons downstream. Alternatively spliced transcripts that delete the mutation were readily amplified from normal colonic mucosa and therefore create a mechanism for the attenuated phenotype seen in this family.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenomatous Polyposis Coli / genetics*
  • Adult
  • Aged
  • Alternative Splicing*
  • Amino Acid Sequence
  • Base Sequence
  • DNA, Complementary
  • Exons*
  • Female
  • Genetic Linkage
  • Humans
  • Male
  • Middle Aged
  • Mutation*
  • Nucleic Acid Heteroduplexes
  • Pedigree
  • Phenotype


  • DNA, Complementary
  • Nucleic Acid Heteroduplexes