OBJECTIVE: To explore the genetic basis for a pedigree affected with familial adenomatous polyposis (FAP). METHODS: The proband, with recurrence of blood in the stool, was diagnosed with FAP by endoscopy, pathological examination and a family history. She was subjected to next generation sequencing to detect genetic variant. Suspected variant was verified by Sanger sequencing of members from her pedigree. RESULTS: The proband, her mother and brother were found to carry a heterozygous c.532-1G>A variant of the APC gene, which may lead to aberrant splicing of mRNA resulting in a truncated protein, which may lose its normal function and promote the tumorigenesis. Based on the American College of Medical Genetics and Genomics standards and guidelines, c.532-1G>A variant of APC gene was predicted to be pathogenic(PVS1+PP1+PP4+PP5). CONCLUSION The c.532-1G>A variant of the APC gene probably underlay the pathogenesis of FAP in this pedigree.
Adenomatous Polyposis Coli/genetics* ; Adenomatous Polyposis Coli Protein/genetics* ; Female ; Genes, APC ; Humans ; Male ; Neoplasm Recurrence, Local ; Pedigree

OBJECTIVE: To analyze the clinical features and genetic basis for a Chinese pedigree affected with familial adenomatous polyposis (FAP). METHODS: Clinical information of the patient was collected. Genomic DNA was extracted from peripheral blood sample of the patient and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing. RESULTS: The proband, a 33-year-old female, was found to have multiple adenomatous polyps in the intestine. WES revealed that she has harbored a heterozygous variant of the APC gene, namely c.1922dupA (p.N641fs*10), which was unreported previously. Based on the guidelines of the American College of Medical Genetics and Genomics, the variant was predicted to be likely pathogenic. CONCLUSION The c.1922dupA (p.N641fs*10) variant of the APC gene probably underlay the FAP in this pedigree. Above finding has enabled genetic counseling for this family.
Female ; Humans ; Adult ; Pedigree ; Adenomatous Polyposis Coli Protein/genetics* ; Germ-Line Mutation ; Adenomatous Polyposis Coli/genetics* ; China ; Mutation

OBJECTIVETo analyze the mutational features of adenomatous polyposis coli (APC) gene and to explore the effect of mismatch repair (MMR) deficiency on its mutations in hereditary non-polyposis colorectal cancers (HNPCC).

METHODSPCR-based in vitro synthesized protein test (IVSP) assay and sequencing analysis were used to confirm somatic mutations of whole APC gene in 19 HNPCC patients.

RESULTSEleven cases with thirteen mutations were determined. The frequency of APC mutation was 58%(11/19). The exhibiting mutations consisted of 9 frameshift mutations and 4 nonsense ones, indicating the existence of more frameshift mutations (69%). All of frameshift mutations were deletion or insertion of 1-2 bp and most of them (7/9) happened at simple nucleotide repeat sequences, particularly within (A) n tracts (5/9). All of four nonsense mutations resulted from C to T transitions at CpG sites.

CONCLUSIONMutational inactivations of APC gene were detected in more than half of HNPCC patients in this study, indicating that APC mutation is a common molecular event in the tumorigenesis of HNPCC. According to the location of frameshift mutations at simple nucleotide repeat sequences and point mutations at CpG sites, it was suggested that endogenous mechanisms like MMR deficiency might exert an effect on the nature of APC mutations in most HNPCC.

Adenomatous Polyposis Coli ; genetics ; Adenomatous Polyposis Coli Protein ; genetics ; metabolism ; Carcinoma ; genetics ; Colorectal Neoplasms ; genetics ; pathology ; Colorectal Neoplasms, Hereditary Nonpolyposis ; genetics ; Genes, APC ; physiology ; Humans

OBJECTIVETo analyze the characteristics of germline mutations of adenomatous polyposis coli (APC) gene in pedigrees affected with familial adenomatous polyposis (FAP).

METHODSGenomic 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.

RESULTSGermline 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.

CONCLUSIONC.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.

Adenomatous Polyposis Coli ; genetics ; Adenomatous Polyposis Coli Protein ; genetics ; Adult ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; China ; Female ; Humans ; Male ; Molecular Sequence Data ; Pedigree ; Sequence Deletion

OBJECTIVEThis study was aimed at establishing an efficient mutation analysis technique system to screen the germline mutations in the adenomatous polyposis coli (APC) gene that predisposes the disease susceptibility in familial adenomatous polyposis (FAP) and to investigate the relationship between genotype and phenotype of APC gene.

METHODSGenomic DNA was extracted from the peripheral blood lymphocytes of 22 patients with clinically diagnosed FAP and was forwarded to screening for germline mutations by using denaturing high-performance liquid chromatography(DHPLC), protein truncation test (PTT) and DNA sequencing in APC gene. Analysis of genotype-phenotype was also performed on the clinical data of the FAP patients.

RESULTSThirteen APC germline mutations were identified in 22 FAP patients. All of the mutations were nonsense or framshift mutations. Analysis of genotype-phenotype demonstrated that the FAP patients with mutations in the 5'or 3'extreme parts of the APC gene showed mild clinical symptoms. However, the FAP patients with mutations in the middle of the APC gene displayed typical or severe clinical symptoms.

CONCLUSIONThe technique system established in this study can efficiently and sensitively detect the mutations in APC gene. It is useful in the molecular diagnosis of pre-symptomatic FAP cases in FAP family. The clinical features of FAP patients may be related to their genotypes of APC gene.

Adenomatous Polyposis Coli ; genetics ; Adenomatous Polyposis Coli Protein ; genetics ; Chromatography, High Pressure Liquid ; DNA Mutational Analysis ; Frameshift Mutation ; genetics ; Genotype ; Germ-Line Mutation ; Humans ; Phenotype ; Polymerase Chain Reaction

Hereditary syndromes cause approximately 5 to 15% of overall colorectal cancer (CRC) cases. Hereditary CRC is conventionally divided into two major categories: hereditary non-polyposis colorectal cancer (HNPCC) and those related to polyposis syndromes including familial adenomatous polyposis (FAP), Peutz-Jegher syndrome (PJS), and juvenile polyposis (JP). The screening for the cancer and methods of treatment applied to patients with hereditary CRC are quite different from those applied to the general population. The genes responsible for these syndromes has recently identified, as a result, genetic testing has become the most important determining factor in clinical decisions. Germ-line mutation of the APC gene induces FAP, an autosomal dominant disorder, characterized by the development of hundreds to thousands of colonic adenomas. CRC appears in almost all affected individuals by the time they are 50 years of age. An affected individual should undergo colectomy by his/her late teens. Furthermore, according to the findings of genetic testing, at-risk family members also need endoscopic surveillance and surgery. Recently, a mutation on the MYH gene is increasingly being investigated in patients with multiple polyps, and autosomal recessive MYH polyposis is considered to be a new category of polyposis. More common than FAP, HNPCC is caused by germ-line mutations in DNA mismatch repair genes, mainly MLH1 and MSH2. Although there is no polyposis, polyps seem to be more villous and dysplastic and appear to grow rapidly into CRCs. The aggregate lifetime risk of CRC is about 80% for mutation carriers. The risk for other types of cancer, such as endometrial, ovarian, small bowel, and transitional cell cancer, is also increased. The Amsterdam criteria and Bethesda guidelines are the best-known tools for diagnosis and genetic testing, and colectomy followed by endoscopic follow-up is the standard treatment. PJS and JP are reported to be characterized by hamartomatous polyps throughout the GI tract and germ-line mutations in the STK11 gene (PJS) and the DPC4/BMPR1A gene (JP).
Adenomatous Polyposis Coli/*genetics ; Colorectal Neoplasms, Hereditary Nonpolyposis/diagnosis/*genetics ; Genetic Predisposition to Disease ; Germ-Line Mutation ; Humans ; Intestinal Polyposis/diagnosis/*genetics ; Peutz-Jeghers Syndrome/diagnosis/*genetics

OBJECTIVETo analyze mutation of adenomatous polyposis coli (APC) gene in a family affected with familial adenomatous polyposis.

METHODSThe diagnosis was made based on clinical manifestations, family history, presence of numerous polyps in the colon as well as pathological examination. Peripheral blood samples were collected, and genomic DNA was extracted. Potential mutation of the APC gene was detected by polymerase chain reaction (PCR) and DNA sequencing. After finding the mutation in the proband, the same mutation was screened among other family members. The mutation was also confirmed with PCR-restriction fragment length polymorphism (RFLP), with which 100 unrelated healthy controls were examined.

RESULTSA novel heterozygous nonsense mutation c.2891T>G (L964X) of the APC gene was identified in this pedigree. The mutation has led to premature termination of translation. The same mutation was not detected among the 100 healthy controls.

CONCLUSIONThe c.2891T>G (L964X) of the APC gene probably underlies the familial adenomatous polyposis in this pedigree. The combined DNA sequencing and PCR-RFLP method is efficient and accurate for the diagnosis.

Adenomatous Polyposis Coli ; diagnosis ; genetics ; Adenomatous Polyposis Coli Protein ; genetics ; Adult ; Base Sequence ; Child, Preschool ; Colorectal Neoplasms ; diagnosis ; genetics ; Female ; Humans ; Male ; Molecular Sequence Data ; Mutation, Missense ; Pedigree ; Point Mutation ; Young Adult

OBJECTIVETo detect the adenomatous polyposis coli (APC) gene germline mutation in the proband and her family members with familial adenomatous polyposis (FAP).

METHODSThe diagnosis of a patient with FAP was validated by colonoscopy, pathology and the family history. The systematic screening with multiplex ligation-dependent probe amplification (MLPA), denaturing high-performance liquid chromatography (DHPLC) and DNA sequencing were carried out to detect APC gene germline mutations.

RESULTSA novel mutation c.1999 C >T (Q667X) of APC, which leads to premature termination of the protein, was identified in this family. This mutation manifested an aggressive form of FAP with early onset of colorectal adenocarcinoma and colonic adenoma.

CONCLUSIONThe mutation of APC Q667X is the cause of clinical phenotype of this family with FAP, and the prophylactic colectomy for the affected family members should be considered.

Adenomatous Polyposis Coli ; genetics ; Adenomatous Polyposis Coli Protein ; genetics ; Adolescent ; Adult ; Base Sequence ; Child ; Chromatography, High Pressure Liquid ; DNA Mutational Analysis ; Female ; Germ-Line Mutation ; Humans ; Male ; Middle Aged ; Pedigree ; Phenotype ; Polymerase Chain Reaction

OBJECTIVETo analyze the adenomatous polyposis coli (APC) gene mutations in familial adenomatous polyposis (FAP) in Chinese.

METHODSDNA was extracted from blood samples taken from 31 FAP families, and all exons of the APC gene were amplified with touch-down PCR. APC gene mutations were screened by denaturing high performance liquid chromatography followed by sequencing if abnormal profile was detected.

RESULTSTwelve categories of APC gene mutations were found in 15 FAP families (48.39%) including 4 novel mutations in coding region and 3 mutations in introns. The 4 novel mutations in coding region were frameshift mutations and located in codons 255, 677, 1192 and 1403 respectively. Most mutations were clustered in exon 15 of APC gene leading to frameshift and accounted for 86.67%. Others were nonsense mutations (13.33%).

CONCLUSIONThe mutation rate of the APC gene in this group of Chinese FAP families was about 48.39%, and 4 novel mutations were detected. Frameshift mutation was the major mutation type in Chinese FAP and mainly located in exon 15.

Adenomatous Polyposis Coli ; genetics ; Chromatography, High Pressure Liquid ; methods ; Exons ; genetics ; Female ; Frameshift Mutation ; genetics ; Genes, APC ; physiology ; Humans ; Introns ; genetics ; Male ; Mutation ; Polymerase Chain Reaction

Adenomatous Polyposis Coli Protein ; genetics ; Chromatography, High Pressure Liquid ; methods ; Codon ; genetics ; DNA Mutational Analysis ; Fibromatosis, Aggressive ; genetics ; pathology ; Humans ; Mutation ; Polymerase Chain Reaction ; beta Catenin ; genetics