title: Molecular screening of families affected by familial adenomatous polyposis (FAP).
abstract: OBJECTIVE
  To assess the risk of developing familial adenomatous polyposis (FAP) in presymptomatic individuals using APC gene flanking and intragenic polymorphic markers.
  
  
  METHODS
  Twenty families enrolled in the Italian Registry of Polyposis comprising a total of 217 individuals, including 53 (24%) presymptomatic subjects with a 50% a priori risk of FAP, were analysed. Direct analysis techniques had previously failed to identify the FAP mutation in these families.
  
  
  METHODS
  DNA isolated from peripheral mononuclear blood cells and tissue sections was analysed by the polymerase chain reaction and a panel of seven highly polymorphic markers--YN5.64, CB83, CB26, LNS, APC1458.5, MBC, 37AB. Amplification products were separated by a modified denaturing gel electrophoresis method.
  
  
  RESULTS
  The haplotype associated with the disease was identified in 18 families (90%). The segregation of the FAP haplotype in these kindreds showed that 10 presymptomatic individuals had inherited the FAP mutation and carried a high risk of developing the disease. The remaining two families were not informative because of the lack of a sufficient number of probands or biological specimens.
  
  
  CONCLUSIONS
  These data indicate that indirect analysis with linked DNA markers has a high rate of success in defining the risk of FAP of presymptomatic subjects, provided that a sufficient number of probands or samples is available. Uninformative families accounted for 10% of the total, indicating that linkage analysis may still have higher sensitivity than direct mutation analysis techniques. The combined use of both approaches should be implemented, however, to enhance further the application of molecular genetics to the screening of families with FAP.
authors.affiliation: Fondazione Centro Studi di Patologia Molecolare Applicata alla Clinica, Milan, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Gazzoli
authors.forename: C
authors.initials: C
authors.lastname: De Andreis
authors.forename: S M
authors.initials: SM
authors.lastname: Sirchia
authors.forename: P
authors.initials: P
authors.lastname: Sala
authors.forename: C
authors.initials: C
authors.lastname: Rossetti
authors.forename: L
authors.initials: L
authors.lastname: Bertario
authors.forename: G
authors.initials: G
authors.lastname: Colucci
mesh_terms: D011125:Adenomatous Polyposis Coli / Q000453:epidemiology* / Q000235:genetics; D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003110:Colonic Neoplasms / Q000235:genetics / Q000517:prevention & control*; D004247:DNA / Q000097:blood / Q000235:genetics; D004252:DNA Mutational Analysis; D004198:Disease Susceptibility; D005260:Female; D017491:Genes, APC; D005820:Genetic Testing; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D012306:Risk
chemical_list: D004247:DNA