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 postsurgical 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.
Different expressivity of two adjacent mutations of the APC gene
PRESCIUTTINI, SILVANO;MOSCA, FRANCO;
1999-01-01
Abstract
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 postsurgical 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
