Marfan-like habitus and familial adenomatous polyposis in two unrelated males: a significant association?

Familial adenomatous polyposis (FAP) can be considered as a condition of th e whole body as extracolonic features derived from all the three embryonic lineages are recorded with varying frequency in addition to the presence of multiple adenomas in the large intestine. Here, we describe two unrelated cases of FAP with unusual extracolonic phenotypes, namely several abnormali ties of mesodermal origin strongly resembling Marfan syndrome (MFS) or a Ma rfan-like habitus, Conventional cytogenetic and FISH analysis did not revea l any gross chromosomal rearrangement on the long arm of chromosome 5 where the APC and FBN2 genes were located, However, in case 2 the FAP-causing mu tation in the APC gene was found in the donor splice site of exon 4 and was shown to result in a frameshift and a premature termination codon, We prop ose that such connective tissue abnormalities may result from germline APC mutations in combination with specific genetic and/or environmental modifyi ng factors.