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Linkage of a variant or attenuated form of adenomatous polyposis coli to the adenomatous polyposis coli (APC) locus.

Adenomatous polyps are an intermediate in the pathway to colon carcinoma. An inherited disorder, familial adenomatous polyposis coli (APC), is characterized by hundreds to thousands of adenomatous polyps. A previously reported family had colon cancer associated with a low average but highly heterogenous number of colonic polyps, this phenotype mapped to the APC locus on 5q. Four new families have been ascertained in which the phenotypic pattern was different from classical polyposis but similar to that of the "prototype" kindred reported earlier. By multilocus linkage analysis, the gene responsible for the disease phenotype was mapped, with a high level of confidence, to the APC locus in two of the four families with the attenuated or variant form of polyposis (AAPC); the results for the two remaining kindreds were inconclusive. A combined maximum LOD score of approximately 7.6 at a recombination fraction of 0 was obtained when the results were summed over the four pedigrees with markers closest to the APC locus. The establishment of genetic linkage in such families may point to the APC locus as having a more significant role in inherited predispositions to colorectal cancer than was previously thought.

Adenomatous Polyposis Coli

An intrachromosomal insertion causing 5q22 deletion and familial adenomatous polyposis coli in two generations.

We report familial adenomatous polyposis coli (FAPC) with epidermoid cysts, osteomata, and areas of congenital hypertrophy of the retinal pigment epithelium (CHRPEs) in a male patient and his maternal aunt, both of whom suffered a mild to moderate degree of mental handicap. Both had an interstitial deletion of the long arm of chromosome 5 (del(5)(q22q23.2)). Two other normal family members had the underlying direct insertion of chromosome 5(dir ins(5)(q31.3q22q23.2)). Molecular genetic and fluorescent hybridisation studies have shown that loci D5S37 and D5S98 are outside the deletion whereas loci detected by probes EF5.44 and YN5.48 are lost. As expected, the molecular analyses indicate loss of one allele at the MCC and APC loci. The APC gene is located within band 5q22. Familial direct insertions should be considered as a cause of recurrent microdeletion syndromes.

Adenomatous Polyposis Coli

Frequent polymorphism in the 13th exon of the adenomatous polyposis coli gene.

We have studied the DNA from 170 individuals affected with familial adenomatous polyposis and from 20 uneffected individuals. Denaturing gradient gel electrophoresis of polymerase chain reaction amplified DNA from the adenomatous polyposis coli (APC) gene demonstrated three major patterns consistent with the existence of two different sequences in exon 13 of the gene in the human population. Direct sequencing of the amplified product from DNAs producing these three patterns confirmed the presence of a polymorphism in the coding region of the APC gene.

Adenomatous Polyposis Coli

[Genetic analysis of adenomatous polyposis coli: analysis of alterations of oncogenes and tumor suppressor genes in colorectal tumors].

Adenomatous polyposis coli (APC) is a genetic disorder transmitted as an autosomal dominant trait. This syndrome is characterized by the development of numerous polyps during the first 20-30 years of life and classified into two phenotypes according to the number of polyps: the profuse and sparse types. If left untreated, most or all affected individuals are at a high risk of developing adenocarcinoma by as early as 40 years of age. Therefore, comparison of APC adenocarcinomas with non-polyposis colorectal carcinomas (NPCC) was thought to be useful for understanding genetically determined carcinogenesis. I investigated gene alterations in specimens obtained from 53 APC patients, of which 16 represented the profuse type and the others the sparse type, and from 15 NPCC patients. The results are summarized as follows: 1) K-ras gene mutations were detected more frequently in the profuse-type adenomas (43%) than in the sparse ones (14%) (p less than 0.05). 2) Loss of heterozygosity on the long arm of chromosome 5(5q), 18(18q) and the short arm of chromosome 17(17p) in the profuse-type adenomas was observed more frequently (22%) than in the sparse ones (7.3%) (p less than 0.05). 3) No significant differences were observed between APC adenocarcinomas and NPCCs regarding the allelic deletions on 5q, 17p and 18q in these tumors. 4) The alteration of the DCC gene, which is known to be involved in the formation of NPCC, was frequently detected in the APC adenocarcinomas, suggesting that similar genetic events are involved in the oncogenesis of adenocarcinomas from APC and NPCC.

Adenomatous Polyposis Coli

Incidence and significance of congenital hypertrophy of the retinal pigment epithelium (CHRPE) in familial adenomatous polyposis coli (FAPC).

As part of a population based study of familial colorectal cancer 33 affected patients with familial adenomatous polyposis coli (FAPC) and 33 relatives, at 50% risk of inheriting FAPC, from 24 kindreds, were identified and examined. Fourteen of the affected patients had extracolonic manifestations of the FAPC gene. Twenty-five of the 33 affected patients had one or more areas of congenital hypertrophy of the retinal pigment epithelium (CHRPE) and 20 had more than three CHRPEs, all having bilateral lesions. There were significant interfamilial differences in the ocular findings. Because of this interfamilial difference in the predisposition to develop CHRPEs it is important to establish the CHRPE status of individual FAPC families before the results of ophthalmoscopy can be used to predict the carrier status of at risk relatives.

Adenomatous Polyposis Coli

Interstitial loss of the same region of 5q in multiple adenomas and a carcinoma derived from an adenomatous polyposis coli (APC) patient.

Accumulation of genetic alterations in oncogenes and tumor suppressor genes causes the transformation of a normal cell into a malignant cell. Recently, Fearon and Vogelstein (Cell 61:759-767, 1990) reported on a model for the genetic pathway in development of colorectal neoplasia. To investigate genetic alterations in colorectal carcinomas, we examined allelic losses on some chromosomes in adenomas and carcinomas derived from patients with adenomatous polyposis coli (APC). We found evidence for an interstitial deletion of 5q. Loss of heterozygosity (LOH) of 5q around the APC locus was observed in both adenoma and carcinoma in one case. The fact that the same region of chromosome 5 was lost in five adenomas and one carcinoma derived from the same patient suggests that a somatic interstitial deletion may be caused not by random mechanisms but by a specific mechanism.

Adenocarcinoma

Familial 'minor' adenomatous polyposis coli associated with gastric carcinoma - a hiterto undescribed phenotype of polyposis coli?

A clinical study of a family (Sch.) with a high incidence of death from gastric cancer in the second generation is presented. Endoscopic and/or surgical evaluation of the stomach, upper small intestine, and colon in 14 mainly asymptomatic members of the third and fourth generations revealed single or multiple (solitary) papillary adenomas in the colon or jejunum in 2 members each of the two generations. In addition, single or multiple hyperplastic polyps in the stomach or colon were found in 5 members, in 4 of them in association with papillary adenomas. The findings in family Sch. are consistent with 'minor' adenomatous polyposis coli associated with gastric carcinoma. Gastric carcinoma probably represents another phenotype among the vast variety of extra-colonic and extra-alimentary neoplastic changes known to occur in association with familial polyposis coli (FPC). The relationship of hyperplastic polyps to papillary adenoma in the colon and to gastric carcinoma respectively is discussed. Finally, evidence for a genetic relationship between family Sch. and a case with probable FPC is presented.

Adenocarcinoma, Papillary

Detection by DGGE of a new polymorphism closely linked to the adenomatous polyposis coli region.

The EF5.44 locus is in close proximity to the chromosome 5 region to which the genetic defect responsible for familial adenomatous polyposis has been mapped. We have devised two oligonucleotides that promote the specific polymerase chain reaction (PCR) amplification of a 365-bp sequence in this region. Analysis by denaturing gradient gel electrophoresis of the resulting fragment has unravelled individual differences that could be identified as a single base pair change in a MnlI restriction site. This PCR assayable polymorphism increases the informativeness at this locus, and should be useful in the presymptomatic diagnosis of familial adenomatous polyposis.

Adenomatous Polyposis Coli

Mutations of the APC (adenomatous polyposis coli) gene in FAP (familial polyposis coli) patients and in sporadic colorectal tumors.

We have isolated several genes on chromosome 5q21 region tightly linked to hereditary familial polyposis coli (FAP) and Gardner's syndrome (GS). Two of these genes (MCC and APC) were found to be somatically altered by point mutation, deletion or insertion in tumors of sporadic colorectal cancer patients. One (APC) of them was also found mutations in the germ line of both APC and GS patients. The identification of these genes has significant implications for understanding the pathogenesis of colorectal neoplasia and for the diagnosis and counseling of individuals with inherited predispositions to colorectal cancer.

Adenomatous Polyposis Coli

Early detection of adenomatous polyposis coli in Gardner's syndrome.

Gardner's syndrome, an autosomal dominant disorder, consists of multiple polyposis of the colon associated with various soft- and hard-tissue tumors. The appearance of adenomatous hyperplasia and polyposis in at-risk patients before adolescence has not been full appreciated. Four preadolescent children from a kindred with Gardner's syndrome were examined by use of colonoscopy and mucosal biopsy. In three children (18 months, 6 years, and 9 years old) adenomatous hyperplasia or polyposis was found. The colon of the fourth child (3 years old) was normal. The three affected children were asymptomatic. The youngest had a barium enema and results were normal. The oldest child had polyps. Biopsies revealed focal atypical hyperplasia of the glands with pseudostratification of the epithelial cells, frequent mitotic figures, and the absence of goblet cells. More severe manifestations were noted in the splenic flexure than in the sigmoid flexure or rectum. The youngest patient showed early adenomatous hyperplasia characterized by a marked reduction of the goblet cells, especially in the surface epithelium. Colonoscopy and mucosal biopsies are mandatory in at-risk children. By deferring colonic examination until adolescence, a patient is placed at risk for malignant degeneration of the adenomatous tumor.

Adenoma

A novel insertion/deletion in APC promotor 1B is associated with both gastric and colon polyposis.

Pathogenic variants in the APC gene are classically associated with autosomal dominant familial adenomatous polyposis (FAP), characterized by tens-to-thousands of colonic adenomatous polyps and a high-penetrance predisposition to colorectal cancer. More recently, specific PVs in the YY1 binding motif of APC promoter 1B have been associated with autosomal dominant gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), characterized by tens-to-thousands of fundic gland polyps and a predisposition to gastric cancer but which are only rarely associated with features consistent with FAP. Although management guidelines currently treat FAP and GAPPS as mutually exclusive conditions, the extent of phenotypic overlap is not well-characterized. Here, we present a multi-clinic and -laboratory collaboration reporting a previously undescribed APC promoter 1B insertion/deletion likely pathogenic variant in a family with mixed GAPPS and FAP phenotype. The family proband is a female of unspecified white ancestry. She was diagnosed with GAPPS at age 30 and, after developing gastric cancer at age 39, underwent curative gastrectomy. She is now 61 with a cumulative history of between 50 and 100 colon adenomas and recently completed subtotal colectomy. Her multi-gene panel testing in 2022 demonstrated a likely pathogenic insertion/deletion (indel) within the APC promoter 1B YY1 binding motif (APC c.-192_-191delATinsTAGCAAGGG). Review of a four-generation pedigree revealed the ages of gastric cancer presentation in the family ranged from 39-60's, with advanced gastric polyposis and prophylactic gastrectomy as early as ages 11 and 13 in the proband's daughter and nephew, respectively. Six of 10 (60%) family members known or presumed to carry the APC likely pathogenic variant underwent colectomy or hemicolectomy due to colon polyposis. The youngest known carrier in the family is a 12-year-old female, and the oldest living carrier is the proband's brother, age 66. A novel APC indel causes concomitant GAPPS and FAP presentations in this previously unreported large kindred. Mixed gastric and colon phenotypes have been rarely described in GAPPS families and the ages of presentation of gastric polyposis are strikingly young in the current family with prophylactic gastrectomies completed as early as age 11 and 13. These ages are significantly younger than the 15 years of age at which national guidelines currently recommend initiation of EGD for screening in GAPPS. Although the mechanism for this combined GAPPS-FAP phenotype is unclear, patients in this family and those with similar APC promoter 1B variants should be offered both gastric and colon cancer risk management.

Adult

Cell and molecular biology of gastrointestinal tract cancer.

The gene for familial adenomatous polyposis coli (APC or FAP), which has previously been linked to chromosome 5q21 has been identified. The APC gene has been found to be altered by point mutations in the germ line of both adenomatous polyposis coli and Gardner's syndrome patients and somatically in tumors from sporadic colorectal cancer patients. During the hunt for the APC gene, the closely linked MCC (mutated in colorectal cancer) gene was identified and found to be altered somatically in tumors from sporadic cancer patients. These data suggest that more than one gene on chromosome 5q21 may contribute to colorectal carcinogenesis and that mutations at the APC gene can cause both adenomatous polyposis coli and Gardner's syndrome. The identification of these genes should aid in the counseling of patients with genetic predispositions to colorectal cancer. Progress has also been made in identifying specific genetic changes that occur in other gastrointestinal cancers. A mutational "hotspot" in the p53 gene in human hepatocellular carcinomas has been identified that could reflect exposure to a specific carcinogen, one candidate being aflatoxin B1.

Adenomatous Polyposis Coli

Correlation between the location of germ-line mutations in the APC gene and the number of colorectal polyps in familial adenomatous polyposis patients.

Recently we have isolated the adenomatous polyposis coli (APC) gene which causes familial adenomatous polyposis (FAP), and its germ-line mutations in a substantial number of FAP patients have been identified. On the basis of this information, we compared the location of germ-line mutations in the APC gene in 22 unrelated patients (12 of whom have been reported previously) with the number of colorectal polyps developed in FAP patients; 17 were sparse types and five were profuse types. All but one of the mutations were considered to cause truncation of the gene product by frame-shift due to deletion (14 cases) or nonsense mutation (seven cases). The location of the germ-line mutations seems to correlate with the two clinical types; germ-line mutations in five FAP patients with profuse polyps were observed between codon 1250 and codon 1464, whereas mutations in 17 FAP patients with fewer polyps were observed in the other regions of the APC gene. The result suggests that the number of colorectal polyps in FAP patients may be associated with a difference in the stability or biological function of the truncated APC protein.

Adenomatous Polyposis Coli

Screening for germ-line mutations in familial adenomatous polyposis patients: 61 new patients and a summary of 150 unrelated patients.

We report here the result of a screening for germ-line mutations in the adenomatous polyposis coli (APC) gene in 61 new familial adenomatous polyposis (FAP) patients as well as a summary of the results of 150 patients. Examination of the entire coding region of the APC gene, based on a ribonuclease protection assay coupled with the polymerase chain reaction (PCR), disclosed mutations that were considered to cause significant defects in the APC product in 97 of 150 unrelated FAP patients. Our findings revealed the following characteristics of the germ-line mutations of APC: 1) the great majority of the mutations were found to truncate the APC product; 2) almost all of the mutations were located within the first half of the coding region; 3) no correlation was observed between the locations of germ-line mutations and extracolonic manifestations in FAP patients; 4) more than 80% of base substitutions in the APC gene were from cytosine to other nucleotides, nearly one-third of which occurred at the GpG site. Our results provide information helpful to an understanding of the APC gene and will also contribute to presymptomatic diagnosis of members in FAP families.

Adenomatous Polyposis Coli

Frequent somatic mutations of the APC gene in human pancreatic cancer.

The APC (adenomatous polyposis coli) gene is responsible for familial adenomatous polyposis and is also associated with the development of sporadic tumors of the colon and stomach. To investigate whether or not mutations of APC play any role in tumors arising in other organs, we examined somatic mutations of this gene in sporadic (nonfamilial) renal cell carcinomas, hepatocellular carcinomas, and cancers of the lung and pancreas. DNAs isolated from tumors were examined by means of a RNase protection analysis, coupled with the polymerase chain reaction followed by DNA sequencing of the polymerase chain reaction products. By screening a part of the APC coding region, we detected somatic mutations in four of ten pancreatic cancers; each of these mutations would yield a truncated APC product due to a 1- or 5-base pair deletion. These results imply that mutations in APC contribute to carcinogenesis in the pancreas.

Base Sequence

Somatic mutations of the APC gene in colorectal tumors: mutation cluster region in the APC gene.

We examined somatic mutations of the adenomatous polyposis coli (APC) gene in 63 colorectal tumors (16 adenomas and 47 carcinomas) developed in familial adenomatous polyposis (FAP) and non-FAP patients. In addition to loss of heterozygosity (LOH) at the APC locus in 30 tumors, 43 other somatic mutations were detected. Twenty-one of them were point mutations; 16 nonsense and two missense mutations, and three occurred in introns at the splicing site. Twenty-two tumors had frameshift mutations due to deletion or insertion; nineteen of them were deletions of one to 31 bp and three were a 1-bp insertion. One tumor had a 1-bp deletion in an intron near the splicing site. Hence, 41 (95%) of 43 mutations resulted in truncation of the APC protein. Over 60% of the somatic mutations in the APC gene were clustered within a small region of exon 15, designated as MCR (mutation cluster region), which accounted for less than 10% of the coding region. Combining these data and the results of LOH, more than 80% of tumors (14 adenomas and 39 carcinomas) had at least one mutation in the APC gene, of which more than 60% (9 adenomas and 23 carcinomas) had two mutations. These results strongly suggest that somatic mutations of the APC gene are associated with development of a great majority of colorectal tumors.

Adenoma