OBJECTIVE: To analyze the characteristics of germline mutations of adenomatous polyposis coli (APC) gene in pedigrees affected with familial adenomatous polyposis (FAP). METHODS: Genomic DNA was extracted from peripheral blood samples from members of the 13 FAP pedigrees. Multiplex ligation-dependent probe amplification (MLPA) was used to detect large fragment deletions of the APC gene. Subsequently, potential mutation was screened from all exons of the APC gene with PCR amplification and direct sequencing. RESULTS: Germline mutations have been identified in 5 FAP pedigrees, which included c.3184_3187delCAAA, c.5432C>T, c.3925_3928delAAAA and c.3925_3929del AAAAG(in two pedigrees). Small deletional mutations were found primarily in the area of AAAAG tandem repeat sequences. CONCLUSION: C.3925_3929 located in AAAAG tandem repeats is probably the hot spot for APC gene mutations, which are mostly deletional mutations, especially the 5 bp base deletion at codon 1309.
OBJECTIVE: To analyze the characteristics of germline mutations of adenomatous polyposis coli (APC) gene in pedigrees affected with familial adenomatous polyposis (FAP). METHODS: Genomic DNA was extracted from peripheral blood samples from members of the 13 FAP pedigrees. Multiplex ligation-dependent probe amplification (MLPA) was used to detect large fragment deletions of the APC gene. Subsequently, potential mutation was screened from all exons of the APC gene with PCR amplification and direct sequencing. RESULTS: Germline mutations have been identified in 5 FAP pedigrees, which included c.3184_3187delCAAA, c.5432C>T, c.3925_3928delAAAA and c.3925_3929del AAAAG(in two pedigrees). Small deletional mutations were found primarily in the area of AAAAG tandem repeat sequences. CONCLUSION: C.3925_3929 located in AAAAG tandem repeats is probably the hot spot for APC gene mutations, which are mostly deletional mutations, especially the 5 bp base deletion at codon 1309.