Localization of the gene for familial adenomatous polyposis on chromosome 5

Loss of heterozygosity involving the APC and MCC genetic loci occurs in the majority of human esophageal cancers

The tumor suppressor gene APC was recently identified, and the cDNA was cloned from chromosome 5q21. Point mutations affecting APC are seen in the hereditary syndrome familial adenomatous polyposis, and point mutations in APC and a closely linked gene, MCC, as well as loss of heterozygosity involving chromosome 5q have been reported in sporadic colon cancer. To our knowledge, loss of heterozygosity involving APC or MCC or both has not yet been described in any other human cancer besides lung cancer. We used the polymerase chain reaction and DNA content flow cytometric nuclear sorting to examine 30 primary human esophageal cancers for loss of heterozygosity of APC or MCC or both. Loss of one allele was detected in 77% of 26 informative cases. These data suggest that loss of heterozygosity of regions on 5q including the APC and MCC genetic loci is involved in the development and/or progression of most human esophageal cancers. They imply that inactivation of APC, MCC, and/or a linked gene on chromosome 5q plays a role in the pathogenesis of some cancers of the upper gastrointestinal tract, as well as in colon cancer and familial adenomatous polyposis.

Progression of colorectal cancer is associated with multiple tumor suppressor gene defects but inhibition of tumorigenicity is accomplished by correction of any single defect via chromosome transfer

Carcinogenesis is a multistage process that has been characterized both by the activation of cellular oncogenes and by the loss of function of tumor suppressor genes. Colorectal cancer has been associated with the activation of ras oncogenes and with the deletion of multiple chromosomal regions including chromosomes 5q, 17p, and 18q. Such chromosome loss is often suggestive of the deletion or loss of function of tumor suppressor genes. The candidate tumor suppressor genes from these regions are, respectively, MCC and/or APC, p53, and DCC. In order to further our understanding of the molecular and genetic mechanisms involved in tumor progression and, thereby, of normal cell growth, it is important to determine whether defects in one or more of these loci contribute functionally in the progression to malignancy in colorectal cancer and whether correction of any of these defects restores normal growth control in vitro and in vivo. To address this question, we have utilized the technique of microcell-mediated chromosome transfer to introduce normal human chromosomes 5, 17, and 18 individually into recipient colorectal cancer cells. Additionally, chromosome 15 was introduced into SW480 cells as an irrelevant control chromosome. While the introduction of chromosome 17 into the tumorigenic colorectal cell line SW480 yielded no viable clones, cell lines were established after the introduction of chromosomes 15, 5, and 18. Hybrids containing chromosome 18 are morphologically similar to the parental line, whereas those containing chromosome 5 are morphologically distinct from the parental cell line, being small, polygonal, and tightly packed. SW480-chromosome 5 hybrids are strongly suppressed for tumorigenicity, while SW480-chromosome 18 hybrids produce slowly growing tumors in some of the animals injected. Hybrids containing the introduced chromosome 18 but was significantly reduced in several of the tumor reconstitute cell lines. Introduction of chromosome 5 had little to no effect on responsiveness, whereas transfer ot chromosome 18 restored responsiveness to some degree. Our findings indicate that while multiple defects in tumor suppressor genes seem to be required for progression to the malignant state in colorectal cancer, correction of only a single defect can have significant effects in vivo and/or in vitro.

Progression of colorectal cancer is associated with multiple tumor suppressor gene defects but inhibition of tumorigenicity is accomplished by correction of any single defect via chromosome transfer

Carcinogenesis is a multistage process that has been characterized both by the activation of cellular oncogenes and by the loss of function of tumor suppressor genes. Colorectal cancer has been associated with the activation of ras oncogenes and with the deletion of multiple chromosomal regions including chromosomes 5q, 17p, and 18q. Such chromosome loss is often suggestive of the deletion or loss of function of tumor suppressor genes. The candidate tumor suppressor genes from these regions are, respectively, MCC and/or APC, p53, and DCC. In order to further our understanding of the molecular and genetic mechanisms involved in tumor progression and, thereby, of normal cell growth, it is important to determine whether defects in one or more of these loci contribute functionally in the progression to malignancy in colorectal cancer and whether correction of any of these defects restores normal growth control in vitro and in vivo. To address this question, we have utilized the technique of microcell-mediated chromosome transfer to introduce normal human chromosomes 5, 17, and 18 individually into recipient colorectal cancer cells. Additionally, chromosome 15 was introduced into SW480 cells as an irrelevant control chromosome. While the introduction of chromosome 17 into the tumorigenic colorectal cell line SW480 yielded no viable clones, cell lines were established after the introduction of chromosomes 15, 5, and 18. Hybrids containing chromosome 18 are morphologically similar to the parental line, whereas those containing chromosome 5 are morphologically distinct from the parental cell line, being small, polygonal, and tightly packed. SW480-chromosome 5 hybrids are strongly suppressed for tumorigenicity, while SW480-chromosome 18 hybrids produce slowly growing tumors in some of the animals injected. Hybrids containing the introduced chromosome 18 but was significantly reduced in several of the tumor reconstitute cell lines. Introduction of chromosome 5 had little to no effect on responsiveness, whereas transfer ot chromosome 18 restored responsiveness to some degree. Our findings indicate that while multiple defects in tumor suppressor genes seem to be required for progression to the malignant state in colorectal cancer, correction of only a single defect can have significant effects in vivo and/or in vitro.

Insertion/deletion polymorphism and other restriction fragment length polymorphisms in the MCC gene

The MCC gene is a candidate as a tumor suppressor gene for colorectal neoplasms. Further, MCC is tightly linked to the familial adenomatous polyposis (FAP) locus by linkage and physical analysis. Hence, restriction fragment length polymorphisms (RFLPs) of this gene might be very useful for presymptomatic diagnosis of individuals in families segregating mutant alleles of the APC gene. Here we report the identification of five polymorphic systems in MCC gene (both cDNA and genomic), one of which is an insertion/deletion polymorphism that is detectable by a polymerase chain reaction method. These five RFLP systems should be useful for linkage studies in FAP and for examining loss of heterozygosity at this locus in colonic polyps and tumors.

Predictive diagnosis of familial adenomatous polyposis with linked DNA markers: population based study

OBJECTIVES

To evaluate the use of polymorphic DNA probes linked to the APC gene in the presymptomatic diagnosis of familial adenomatous polyposis.

DESIGN

Four DNA probes were tested on an unselected population of patients at risk of familial adenomatous polyposis.

SUBJECTS

The first 47 families notified to the West Midlands familial adenomatous polyposis register. Plus five families sent to our hospital as part of the West of Britain DNA consortium.

MAIN OUTCOME MEASURES

The proportion of families and family members in whom DNA testing could be used to adjust the estimate of risk.

RESULTS

Only 17 families on the register (containing 46% (74/162) of the population at risk) had a suitable pedigree structure for DNA analysis. DNA was analysed in 12 of these families plus the five families from the West of Britain consortium. At least one probe was informative in 27 of the 33 subjects born with 50% risk, but the most informative probe (pi 227) was the one with the highest recombination rate (10%). Flanking markers were informative in only four of the 33 subjects.

CONCLUSIONS

These findings confirm the potential for accurate predictive diagnosis of familial adenomatous polyposis with polymorphic DNA probes, but such an approach is currently limited to about one third of affected families. A combined approach to presymptomatic diagnosis, which includes DNA testing and indirect ophthalmoscopy, is advocated.

Risk estimation in familial adenomatous polyposis using DNA probes linked to the familial adenomatous polyposis gene

The familial adenomatous polyposis gene has recently been assigned to the long arm of chromosome five through linkage to several 5q DNA probes. These probes can now be used to trace inheritance of the disease gene in affected families. In this study, DNA samples from 152 members of 10 Australian familial adenomatous polyposis families have been examined for restriction fragment length polymorphisms detected by DNA probes C11P11, ECB27, and YN5.48. Linkage analysis confirmed linkage between the familial adenomatous polyposis gene and each probe with a maximum combined LOD score of 2.82 for C11P11, 2.90 for ECB27 and 5.49 for YN5.48 all at a recombination fraction of zero. Risk estimates were determined for the 51 at risk individuals in these families based on their restriction fragment length polymorphism data alone or in addition by including the effect of age dependent penetrance. Thirty two of those at risk (63%) could be assigned specific high (greater than or equal to 95%) or low (less than or equal to 5%) risks of developing familial adenomatous polyposis on the basis of their probe results. When the effect of age dependent penetrance was included, 26 (51%) fell at the extremes of risk (greater than or equal to 99% or less than or equal to 1%). Such estimates provide a sound basis for planning sigmoidoscopic screening of at risk family members and will thus facilitate surveillance in familial adenomatous polyposis families.

Hepatoblastoma in two cousins in a family with adenomatous polyposis. Report of two cases

Two cases of hepatoblastoma in cousins in a family with familial adenomatous polyposis (FAP) are reported. Twenty-five cases of hepatoblastoma with family history of FAP have been documented in the literature, but there has never been a report of two cases of hepatoblastoma in the same polyposis family.

Colonoscopy in patients with a family history of colorectal cancer

Since 1982 it has been the second author's policy to advise all patients who have presented with a positive family history of bowel cancer and who are over the age of 30 years to undergo colonoscopy. In the period to August 1990, 600 such patients had at least one colonoscopy. Colorectal polyps or cancer were detected in 270 patients (45 percent). The incidence was essentially the same for the 171 patients with only second-degree relatives affected (43 percent), for the 194 patients with more than one affected relative (45 percent), and for the 429 patients with an affected first-degree relative (46 percent). Only the 55 patients with more than one affected first-degree relative had a higher incidence (67 percent). The incidence in the 136 totally asymptomatic patients was 36 percent but was 48 percent in the 464 with symptoms. In 37 patients carcinoma was diagnosed. Even in the 30- to 39-year age group there was a 29 percent incidence of polyps or carcinoma. Colonoscopic screening of patients with a family history of bowel cancer compares favorably with mass screening for breast cancer. It is currently advised that all patients over 30 years of age with a family history of colorectal cancer undergo colonoscopy on presentation and, if clear, every four years thereafter unless two first-degree relatives are affected, when it should be every two years.

The Min (multiple intestinal neoplasia) mutation: its effect on gut epithelial cell differentiation and interaction with a modifier system

Min is a fully penetrant dominant mutation that leads to the development of multiple intestinal adenomas throughout the duodenal-to-colonic axis. Min/+ C57BL6/J mice have an average life-span of 120 d. Multi-label immunocytochemical studies of these lesions demonstrate patches of differentiated enterocytes, and scattered enteroendocrine, goblet and Paneth cells. Expression of endogenous marker genes within these differentiated cells can be directly correlated with the position occupied by the adenoma along the duodenal-to-colonic axis and mirrors the regional differentiation of the normal gut epithelium. The presence of multiple lineages in adenomas together with their retention of spatial information suggests that tumorigenesis in Min/+ mice may be initiated in a multipotent stem cell normally located at the base of intestinal crypts. To study the time-dependent properties of these tumors, genetic conditions were sought in which Min/+ animals could survive for up to 300 d. Min is fully penetrant in hybrids with either AKR/J or MA/MyJ. However, the hybrids demonstrate a reduction in the number of intestinal adenomas. Preliminary backcross analysis is consistent with a single major modifier locus unlinked to Min in both the AKR/J and MA/MyJ strains. The increased lifespan of the hybrid animals is also associated with the development of invasive tumors. New tumors do not arise continuously over the lifespan of these animals; instead all adenomas appear to be established by 100 d of age or sooner. These studies indicate that the Min/+ mouse is a powerful model system for analyzing the mechanisms that establish and maintain a balance between proliferation and differentiation in the continuously renewing gut epithelium and for an assessment of the multi-step hypothesis of intestinal neoplasia.

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.

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.

Hereditary melanoma and the search for the melanoma gene

The discovery and characterization of growth regulatory genes, in the form of oncogenes, and their counterparts, tumor suppressor (TS) or antioncogenes, has vastly expanded the basic understanding of tumorigenesis. Human solid tumors, such as colorectal cancer, for which the molecular genetics have been most clearly defined, display progressive evolution from cellular dysplasia to anaplasia and metastasis through the stepwise accumulation of genetic defects, involving the regulation and expression of both oncogenes and TS genes. The study of basic genetic abnormalities in melanoma and the identification of the most fundamental of these is critical both to the understanding of abnormal melanocyte proliferation and its potential pharmacologic or immunologic regulation, and also to the identification and screening of patients at high risk for the development of melanoma. The search for such genetic abnormalities has included an analysis of melanomas for defects in known characterized oncogenes and TS genes, and, more importantly, the use of families with hereditary melanoma (HM) and dysplastic nevi in an endeavor to find the melanoma gene. The importance of HM is fundamental, since in the case of other hereditary cancer syndromes for which the genetic basis has been identified, the same or similar genetic abnormalities underlie sporadic tumors of the same tissue type. Thus HM is likely to be the major signpost to the melanomagenic defect.

Cytonuclear morphometry in the assessment of dysplasia in colorectal adenomatous polyps. A pilot study

In order to objectify the degree of dysplasia, results of nuclear and cellular morphometry were compared with assessed grades of dysplasia in 32 colorectal adenomatous polyps. Of these adenomas 8 showed mild, 17 moderate and 7 severe dysplasia (according to blind duplicate assessments by two pathologists). Using a microscope video-overlay interactive digitizing measurement system, 100 nuclei were measured in each specimen according to a strict measurement protocol. In a stepwise discriminant analysis the best discriminating features appeared to be mean stratification index, N/C ratio, mean contour ratio and mean form AR. Overall with these features 65.6% correct jackknifed classification of the 32 cases could be achieved. On the other hand, a clear three-group distinction could not be obtained, even with the best set of discriminating features. Similarly to gastric dysplasia, the morphometric features might be used to design a two-grade (low, high) rather than a three-grade system to assess the degree of dysplasia. These findings make clear that objectifying the degree of dysplasia in adenomatous polyps is possible by means of interactive morphometric analysis.

Cutaneous manifestations of gastrointestinal disorders. Part I

This article reviews the cutaneous manifestations of gastrointestinal tract diseases. In part I, the gastrointestinal tract polyposis syndromes and gastrointestinal tract malignancies will be discussed. The cutaneous manifestations of inflammatory bowel disorders, vascular disorders of the gastrointestinal tract, celiac disease and bowel-associated dermatosis-arthritis syndrome will be discussed in part II. For each entity, a brief summary of the gastrointestinal tract (and other extracutaneous) manifestations is given. This is followed by a detailed discussion of the cutaneous signs. Current guidelines for the investigation and management of these diseases are presented.

Clonal chromosomal abnormalities in desmoid tumors. Implications for histopathogenesis

Desmoid tumors (aggressive fibromatosis) are regarded as lesions of uncertain histopathogenesis. Cytogenetic analyses of 26 desmoid tumor specimens from abdominal or extraabdominal sites of 22 patients with or without Gardner's syndrome (GS) showed clonal karyotypic abnormalities in 7 cases, random abnormalities in 14 cases, and striking telomeric fusion in 5 cases. Loss of chromosome Y, a reported feature of fibromatosis in penile and palmar locations, was detected as a clonal aberration in two patients. Additionally, involvement of 5q was observed in six patients, two of whom had GS. Clonal interstitial deletions of 5q were observed in three patients, one with and two without GS. These findings confirm a clonal and probable neoplastic origin for desmoid tumor and suggest that abnormalities of the Y chromosome and 5q may be important in the genesis of this neoplasm.

Multistage carcinogenesis in paediatric and adult cancers

Retinoblastoma (RB) and the familial adenomatous polyposis/colorectal cancer (FAP/CRC) complex provide well-characterised examples of multistage carcinogenesis and inheritance of a predisposition to cancer. Retinoblastoma appears to conform to the simple two-step model first proposed by Knudson. The gene responsible for RB, now called Rb1, has been located in chromosome region 13q14. The Rb1 gene has been cloned and subjected to extensive analysis. It is probable that the Rb1 gene product has a role in the regulation of transcription. The familial form of RB occurs as the result of a germline mutation of one of the copies of the Rb1 gene. Colorectal cancer, in contrast, appears to be the result of four or five steps involving both activation of oncogenes and inactivation of antioncogenes. The FAP gene has been located in chromosome region 5q21 by genetic linkage, and a candidate gene, MCC (mutated in colon cancer), has been cloned. Other mutations in previously-identified genes that have been identified as important in the genesis of CRC include the activation of p53 and of Ki-ras. A gene lying in chromosome region 18q which is deleted in colorectal cancer, and hence named DCC has been cloned. Its protein product has sequence homology to neural cell adhesion molecules and other related cell-surface glycoproteins. Delineation of the genes involved in the development of tumours such as RB and CRC provides insight into the mechanisms by which sequential mutations result in carcinogenesis.

Molecular biology in the diagnosis and prognosis of solid and lymphoid tumors

The application of molecular biology to the study of human malignancies has led to tremendous gains in our understanding of their pathogenesis. Although their practical applications are still somewhat limited at this point, the use of molecular diagnostic tools is likely to grow at a very rapid rate as newer and more accurate prognostic markers are identified. The availability of reliable prognostic markers should allow earlier intervention in patients with aggressive disease but exhibiting only limited extent of disease at the time of initial diagnosis. Early intervention in such cases could realistically increase the probability of cure, since highly aggressive tumor cells are more likely to be eliminated by early institution of cytotoxic chemotherapy (4). The p53 tumor suppressor gene clearly represents the most promising potential prognostic marker at present, because of both the multiple phenotypic alterations caused by different p53 mutations and the high frequency of p53 mutations which have been observed in a variety of human cancers. Other prognostic markers related to oncogenes and tumor suppressor genes are almost certain to follow. Validation of new prognostic markers requires a knowledge of both histopathologic diagnostic criteria as well as the consequences for the patient of each diagnosis. There is bound to be some "shake-out" in the field of molecular diagnostics just as there was with other recently introduced techniques such as immunohistochemistry and flow cytometry which were found to provide additional useful information for some tumors and not for others. Since the clinical-pathologic studies needed for verification of putative prognostic markers require relatively long periods of follow up, progress in this area will almost certainly lag behind the ability of molecular biologists to identify new and potentially useful prognostic markers. Our collective ability to reap tangible gains in the clinical arena from our heavy investments in molecular biology and biotechnology depends to a large extent on open channels of communication between clinical and basic scientists. As our ever-increasing insights into oncogenic processes spawn new diagnostic and prognostic markers, our priorities should remain focused on those areas which are inadequately addressed by current methods, and we should avoid the technological trap of devising redundant solutions which increase the expense, but not the efficiency of patient care.

Gene mapping of ocular diseases

Increasing awareness of the role of genetic factors in the causation of many human eye diseases has made ocular genetics one of the fastest growing areas of ophthalmology. The objective of this paper is to present the basic principles of gene mapping and their application to ophthalmology. The techniques used to map the genome are reviewed with emphasis placed on molecular genetics. The advances in this area have already provided the major impetus to the areas of diagnosis and prevention of some genetic eye disorders. Tables are presented that list the autosomal, X-linked and mitochondrial assignment of eye genes and disorders with ocular involvement.

Suppressor gene alterations in the colorectal adenoma-carcinoma sequence

Tumorigenesis is thought to be a multistep process in which genetic alterations accumulate to bring about the neoplastic phenotype. Colorectal tumors appear to arise as a result of the mutational activation of oncogenes coupled with the inactivation of several tumor suppressor genes. We have found frequent allelic deletions of specific portions of chromosomes 5, 17, and 18 which presumably harbor suppressor genes. The target of allelic loss events on chromosome 17 has been shown to be the p53 gene, which is frequently mutated not only in colon cancer but in several other tumor types as well. Candidate suppressor genes have also recently been identified on chromosomes 18 and 5. The DCC gene on chromosome 18q encodes a protein with significant sequence similarity to neural cell adhesion molecules and other related cell surface glycoproteins. Alterations of this gene may interfere with normal cell growth and differentiation by disrupting cell-cell or cell-substrate interactions. Two genes (MCC and APC) on chromosome 5q have also recently been identified and partially cloned. These genes are located in a region tightly linked to familial adenomatous polyposis (FAP). While MCC mutations have been found only in sporadic colon tumors, APC mutations have been identified in sporadic tumors as well as the germline of patients with FAP. Studies are currently in progress to increase our understanding of how alterations of these genes affect colorectal tumor cell growth.

Gastrointestinal cancer: pathogenesis, risk factors and the development of intermediate biomarkers for chemoprevention studies

Dietary, environmental and genetic factors contribute to the etiology, pathogenesis and risk for gastrointestinal cancers. Measurements of cell proliferation and differentiation further identify abnormal cellular properties associated with increased susceptibility to gastrointestinal cancer. In precancerous esophagus, the proliferative compartment increases in size, increased ploidy and dysplasia develop, and epithelial cells express abnormal cytokeratins and ectopic tumor-associated antigens. In precancerous stomach, increased proliferative activity and metaplasia develop. Intestinal enzymes and mucins are expressed and normal gastric antigens are replaced by intestinal or embryonic antigens. In flat colonic mucosa and in colonic adenomas, expansions of the proliferative compartment occur. Gene expression is modified, gene deletions occur and blood group-related antigens are modified as the cells undergo abnormal differentiation and develop into adenomas and carcinomas. Chemopreventive regimens are now being tested to determine whether they modify such intermediate biomarkers toward normal levels characteristic of lower risk for neoplasia. It is anticipated that the utilization of intermediate biomarkers in chemoprevention studies may permit more novel chemopreventive regimens to be tested in human subjects than heretofore was possible.

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.

Gardner syndrome: study and follow-up of a family

A study is in progress of a family (Family P) with Gardner syndrome (familial adenomatous polyposis with extraintestinal manifestations-FAPG). Occult bone lesions of the jaws and ocular fundus lesions were found in a number of affected and at-risk relatives. In some, these "markers" were found early in life before the appearance of colonic polyps. Family P is remarkable for differences in expression of the gene manifested by differences in the age-at-onset of polyps of the colon, in number and size of polyps, and in occurrence of desmoids. These differences may explain why some at-risk relatives wisely followed medical surveillance plans while others, who lacked symptoms, failed to do so. Others without medical guidance undertook their own independent "treatment." As knowledge about extracolonic lesions has increased and surgical treatment for FAPG improved from the time the first affected member of Family P received her diagnosis in 1953, the outlook for survival has also improved. Family communication and that among professionals treating families with FAPG may be improved as worldwide Polyposis Registries increase in number. The risk of postsurgical extraintestinal complications is reason enough to urge life-long medical surveillance for all at-risk relatives.

Gardner syndrome in a boy with interstitial deletion of the long arm of chromosome 5

We described a 15-year-old boy with Gardner syndrome (GS), mental retardation, and craniofacial abnormalities. High-resolution banding analysis showed an interstitial deletion of the long arm of chromosome 5 (q22.1----q31.1). The breakpoints in the present case and in 3 previously reported 5q- patients with adenomatous polyposis coli suggest that the gene responsible for GS/or familial polyposis coli (FPC) is in the 5q22 region, a result consistent with the findings of linkage studies.

Distribution of Ha-ras alleles in patients with colorectal cancer and Crohn's disease

The allele distribution of the Ha-ras gene on chromosome 11p was analysed by the restriction fragment length polymorphism of the enzymes Mspl/Hpall in 238 individuals. The investigation covered 116 patients with colorectal carcinoma and 122 patients with Crohn's disease, representing two patient populations with the same ethnic origin, one with a malignant and the other a benign disease of the same organ system. A total of 17 different alleles were detected belonging to the common, intermediate, and rare classes according to the original nomenclature of Ha-ras alleles. Patients with Crohn's disease showed no difference in the distribution of Ha-ras alleles when compared with expected frequencies. In patients with colorectal carcinoma, the frequency of rare alleles was significantly increased compared with the patients with Crohn's disease (chi 2 = 8.166; Fisher's exact test = 0.005) and with a reference population of 424 cancer free individuals (chi 2 = 49.312; Fisher's exact test = 0.000). Homozygosity was not detected for any rare allele. The occurrence of a rare Ha-ras allele was not linked to the location of the colorectal tumour. These results confirm the hypothesis that unique Ha-ras alleles represent an inherited factor which predisposes the development of colorectal cancer.

Regional mapping of 22 microclones around the adenomatous polyposis coli (APC) locus on chromosome 5q

A previously described genomic library constructed from microdissected DNA has been used to generate a large number of probes around the adenomatous polyposis coli (APC) gene at 5q22. A total of 202 clones were hybridised directly onto a somatic cell hybrid panel containing two APC-related interstitial deletions. Of 75 microclones that gave clear hybridisation signals, 22 independent clones mapped into the region common to both deletions. In addition, 4/22 of the markers are conserved in rodent DNA. These clones should provide a valuable resource for screening cDNA libraries and cloning the DNA around the APC gene in yeast artificial chromosomes.

Characterization and mapping of microdissected genomic clones from the adenomatous polyposis coli (APC) region

The gene associated with adenomatous polyposis coli (APC) has been mapped to the long arm of chromosome 5. To saturate the APC region with DNA markers, two independent microdissection libraries with an emphasis on 5q21.2-21.3 and 5q22 have been constructed from GTG-banded human metaphase chromosomes. PCR-amplified insert DNA of the primary amplificate used as a probe in chromosomal in situ suppression (CISS) hybridization of human metaphase spreads revealed region-specific signals at the chromosomal site that was excised for cloning. One hundred forty-two inserts, derived from both libraries, have been characterized in more detail. Deletion mapping analysis was performed with 17 single-copy clones on a hamster-human hybrid cell panel. Seven of these clones were located within two interstitial deletions of 6-8 Mb from APC-affected individuals around chromosome bands 5q21-22. The identification of new microclones mapping into these deletions and their use in isolating YAC clones should contribute to the construction of a contiguous physical map of the APC region.

Linkage analysis in adenomatous polyposis coli: the use of four closely linked DNA probes in 20 UK families

Linkage analysis was carried out on 20 unselected UK families segregating for adenomatous polyposis coli (APC) using four closely linked DNA probes. Significant lod scores were obtained between APC and three markers: pi 227 (D5S37) theta = 0.16; C11p11 (D5S71) theta = 0.10; and YN5.48 (D5S81) theta = 0.00. The fourth, ECB27 (D5S98), gave low lod scores. The APC gene showed linkage with at least one of the probes used in all families, which is in agreement with previous publications. Combined lod scores are now sufficiently high to allow the use of these probes in presymptomatic diagnosis. Despite the fact that 61% of persons at risk were informative for at least one DNA marker, only 15% were informative with flanking probes. One prenatal diagnosis was performed where the initial request had been for sterilisation.

Value of combined phenotypic markers in identifying inheritance of familial adenomatous polyposis

Familial adenomatous polyposis is an autosomal dominant disease characterised by the development of hundreds of colorectal adenomas in young adults. Occult radio-opaque jaw lesions and pigmented ocular fundus lesions (formerly called congenital hypertrophy of the retinal pigment epithelium) are extraintestinal phenotypic markers for this disorder. We evaluated the usefulness of the combination of these markers for identifying patients who have inherited familial adenomatous polyposis. Forty three affected patients and 12 unaffected first degree relatives from 24 families with familial adenomatous polyposis, including four families without extraintestinal manifestations, were examined for both phenotypic markers. Thirty three of the 43 patients (77%) with familial adenomatous polyposis were positive for both markers, including patients from two families without extraintestinal manifestations. By contrast, only one of 12 (8%) unaffected first degree relatives over 35 years of age had both markers. The sensitivity of the combination of these markers in identifying patients who inherited familial adenomatous polyposis was 77%, the specificity 92%, the predictive value of a positive test 97%, the predictive value of a negative test 52%, and the efficacy 80%. The combined markers had improved efficacy over either marker alone (70% for occult radio-opaque jaw lesions and 67% for pigmented ocular fundus lesions). We conclude that the presence of both occult radio-opaque jaw lesions and pigmented ocular fundus lesions in a person at risk indicates a high probability of inheritance and expression of familial adenomatous polyposis.

Fine mapping of probes in the adenomatous polyposis coli region of chromosome 5 by in situ hybridization

The gene for adenomatous polyposis coli has been localized to 5q21-22. We have mapped six probes from this region using isotopic or nonisotopic in situ hybridization. Using tritium-labeled probes we localized II227 (D5S37) to 5q14-15 and ECB27 (D5S98) to 5q21. Following hybridization with biotin-labeled probes, the positions of signals along the chromosomes were measured as fractional length relative to the length of the chromosome arm from centromere to qter (FLcen-qter). Ninety-five percent confidence limits, compared with standard karyotypes, provided the corresponding band localization. By this method we localized Cllpll (D5S71) to FLcen-qter 0.407-0.452 (5q21.1-21.3), ECB27 to FLcen-qter 0.426-0.473 (5q21.3), YN5.48 (D5S81) to FLcen-qter 0.459-0.496 (5q21.3-22.2), and ECB134 (D5S97) to FLcen-qter 0.509-0.533 (5q22.3-23.1). ECB220 had three sites of hybridization, a major site at FLcen-qter 0.460-0.492 (5q21.3-22.1) and minor sites at FLcen-qter 0.299-0.339 (5q14.3-15) and FLcen-qter 0.629-0.691 (5q23.3-31.2). We have shown that the chromosome 5 breakpoint in a t(5;15) translocation from a patient with Gardner's syndrome (GM03314) is between Cllpll and ECB27. Linkage data are presented suggesting that ECB27 is located on the same side of the APC locus as II227. These and published results including data on several constitutional deletions (M, SD, and brothers PW and ND) give a probable order of [cen] - [II227, proximal SD breakpoint] - [Cllpll] - [proximal PW/ND, M breakpoint(s), GM03314 breakpoint] - [ECB27] - [APC] - [YN5.48] - [distal PW/ND breakpoint] - [ECB134] - [distal M breakpoint] - [qter]. The major site of ECB220 appears to be between ECB27 and the distal PW/ND breakpoint; the distal SD breakpoint is distal to YN5.48.

Frequent loss of heterozygosity at the MCC locus on chromosome 5q21-22 in sporadic colorectal carcinomas

Recent studies have identified a gene on chromosome 5q, designated MCC (mutated in colorectal cancers), as a candidate for the putative colorectal tumor suppressor gene that is located at 5q21. We examined loss of heterozygosity (LOH) at the MCC locus and its vicinity in sporadic colorectal carcinomas, using 12 RFLP (restriction fragment length polymorphism) markers. One clone, L5.71, had been used to identify the MCC gene; all 12 markers also had tight linkage to the gene responsible for adenomatous polyposis coli. All 40 cases studied were informative with at least one marker, and 22 of them (55%) showed LOH at one or more loci. LOH in the tumors was more frequent in the immediate vicinity of L5.71 than in distant parts of the chromosome, and a common region of deletion was detected between markers L5.62 and 15A6. In one case, alleles were retained at L5.71 and at loci proximal to L5.71, but alleles were lost at loci distal to L5.71. In another case, both alleles were retained at L5.71 but alleles were lost at loci proximal and distal to L5.71. These results support the conclusion that a tumor suppressor gene for colorectal carcinoma is located within or around locus L5.71.

Genetics of non-insulin dependent diabetes mellitus in 1990

Family studies suggest a strong genetic component in the aetiology of non-insulin dependent diabetes (NIDDM), with evidence for a major gene of co-dominant or dominant effect. A gene-dosage effect, whereby diabetes develops earlier in people with two susceptibility genes than in those with one susceptibility gene is likely. The search for the diabetes gene has led to the cloning and characterization of many genes involved in controlling glucose homeostasis. These include the insulin, insulin receptor, glucose transporter, amylin and glucokinase genes. Molecular techniques have permitted rapid screening of these genes in NIDDM patients and controls. There is now a rather contradictory genetic literature for NIDDM, with weak disease associations reported and refuted for most candidate genes. However, pedigree analyses and DNA sequencing of available candidate genes and their regulatory regions have failed to implicate any of these in the common form of diabetes, NIDDM. Methodical application of random clones in well-defined NIDDM families may be the strategy of choice in finding the NIDDM genes, given the wide range of genes potentially involved in the glucose and lipoprotein metabolic disturbances seen in NIDDM.

Ribosomal protein genes are overexpressed in colorectal cancer: isolation of a cDNA clone encoding the human S3 ribosomal protein

We have isolated a cDNA clone encoding the human S3 ribosomal protein from a normal human colon cDNA library. The clone was identified as one of many that detected genes whose level of expression was increased in adenocarcinoma of the colon relative to normal colonic mucosa. Increased levels of the S3 transcript were present in the tumors of all eight patients examined. Moreover, the S3 mRNA was also more abundant in 7 of 10 adenomatous polyps, the presumed precursor of carcinoma. Additional studies demonstrated that increased levels of mRNAs encoding several other ribosomal proteins, including S6, S8, S12, L5, and P0, were present in colorectal tumors and polyps. These results suggest that there is increased synthesis of ribosomes in colorectal tumors and that this increase is an early event in colon neoplasia.

Identification of FAP locus genes from chromosome 5q21

Recent studies suggest that one or more genes on chromosome 5q21 are important for the development of colorectal cancers, particularly those associated with familial adenomatous polyposis (FAP). To facilitate the identification of genes from this locus, a portion of the region that is tightly linked to FAP was cloned. Six contiguous stretches of sequence (contigs) containing approximately 5.5 Mb of DNA were isolated. Subclones from these contigs were used to identify and position six genes, all of which were expressed in normal colonic mucosa. Two of these genes (APC and MCC) are likely to contribute to colorectal tumorigenesis. The MCC gene had previously been identified by virtue of its mutation in human colorectal tumors. The APC gene was identified in a contig initiated from the MCC gene and was found to encode an unusually large protein. These two closely spaced genes encode proteins predicted to contain coiled-coil regions. Both genes were also expressed in a wide variety of tissues. Further studies of MCC and APC and their potential interaction should prove useful for understanding colorectal neoplasia.

Mutations of chromosome 5q21 genes in FAP and colorectal cancer patients

Previous studies suggested that one or more genes on chromosome 5q21 are responsible for the inheritance of familial adenomatous polyposis (FAP) and Gardner's syndrome (GS), and contribute to tumor development in patients with noninherited forms of colorectal cancer. Two genes on 5q21 that are tightly linked to FAP (MCC and APC) were found to be somatically altered in tumors from sporadic colorectal cancer patients. One of the genes (APC) was also found to be altered by point mutation in the germ line of FAP and GS patients. These data suggest that more than one gene on chromosome 5q21 may contribute to colorectal neoplasia, and that mutations of the APC gene can cause both FAP and GS. The identification of these genes should aid in understanding the pathogenesis of colorectal neoplasia and in the diagnosis and counseling of patients with inherited predispositions to colorectal cancer.

Identification and characterization of the familial adenomatous polyposis coli gene

DNA from 61 unrelated patients with adenomatous polyposis coli (APC) was examined for mutations in three genes (DP1, SRP19, and DP2.5) located within a 100 kb region deleted in two of the patients. The intron-exon boundary sequences were defined for each of these genes, and single-strand conformation polymorphism analysis of exons from DP2.5 identified four mutations specific to APC patients. Each of two aberrant alleles contained a base substitution changing an amino acid to a stop codon in the predicted peptide; the other mutations were small deletions leading to frameshifts. Analysis of DNA from parents of one of these patients showed that his 2 bp deletion is a new mutation; furthermore, the mutation was transmitted to two of his children. These data have established that DP2.5 is the APC gene.

Identification of deletion mutations and three new genes at the familial polyposis locus

Small (100-260 kb), nested deletions were characterized in DNA from two unrelated patients with familial adenomatous polyposis coli (APC). Three candidate genes located within the deleted region were ascertained and a previous candidate gene, MCC, was shown to be located outside the deleted region. One of the new genes contained sequence identical to SRP19, the gene coding for the 19 kd component of the ribosomal signal recognition particle. The second, provisionally designated DP1 (deleted in polyposis 1), was found to be transcribed in the same orientation as MCC. Two other cDNAs, DP2 and DP3, were found to overlap, forming a single gene, DP2.5, that is transcribed in the same orientation as SRP19.

Chromosome changes in desmoid tumors developed in patients with familial adenomatous polyposis

Chromosome analyses were performed on benign desmoid tumors obtained from two female patients with familial adenomatous polyposis (FAP), one of whom was diagnosed as having Gardner syndrome (GS). The modal chromosome number was 46 in both specimens, and detailed Q-banding analysis in Case 1 (GS) revealed a clonal abnormality of an interstitial deletion of the long arm of chromosome 5, del(5)(q21q31). The deleted region included an assigned locus for an FAP major gene (5q21-q22). All of the metaphases analyzed in this case showed an extra segment of bright fluorescence on the short arm of chromosome 15, but this unusual chromosome (15p+) was observed in both peripheral lymphocyte and skin fibroblast cultures from the patient, indicating that the 15p+ was constitutional in nature. In Case 2, no clonal rearrangements were identified and most cells had a normal karyotype. However, two cells showed rearrangements involving a 17q with non-identical breakpoints, one of which was observed as a solitary chromosome change. Based on the present findings in Case 1 and those reported so far, the chromosomal defect on 5q might be one of the causal genetic events primarily associated with the development of both benign desmoid tumors and colorectal adenomas and carcinomas in FAP patients.

A mathematical computer stimulation model for the development of colonic polyps and colon cancer

Currently known information about the development and progression of colon polyps and cancer is summarized and organized into a mathematical computer simulation model that successfully predicts the natural history of colon polyp and cancer development for an average patient with (1) familial polyposis coli (2) genetic susceptibility as measured by a positive family history, and (3) negative family history with a high fat diet. The mathematical model uses four distinct types of cells (normal, transformed, polypoid, and cancerous) and two kinetic processes (mutation and promotion). Arachidonic acid metabolites play a role in the model in the promotion of cancer from polyps, and account for that promotion through: (1) their effect on encouraging more polypoid cells in mitosis to move toward cancer; and (2) their immunosuppressive effect over time. The model also shows that one defect in allowing more cells to mutate to the transformed state is sufficient to account for the chain of events leading to the clinical sequelae of familial polyposis coli. A second genetic effect at another point in the process is unnecessary. The mechanism of action of Sulindac on colon polyps is explained by the model through inhibition of production of arachidonic acid metabolites, most notably prostaglandin E.

A case report of juvenile polyposis with adenomatous change and a review of 34 cases reported in Japan

It has recently come to be thought that cases of juvenile polyposis have a natural tendency to develop adenoma and/or carcinoma. Here we present a case of juvenile polyposis coli with adenomatous change in a 21-year-old male, with a review of 34 cases of juvenile polyposis in the Japanese literature, and discuss the pathogenetic development of the polyps and their malignant potential. In this case, focal or entire adenomatous areas were found in large part of the polyps in the resected sigmoid colon and rectum, though these findings had not been recognized in 23 polypectomy specimens from the rectum 10 months prior to the operation. It was suggested that adenomatous change developed quickly in a very short time.

Ribosomal protein genes are overexpressed in colorectal cancer: isolation of a cDNA clone encoding the human S3 ribosomal protein

We have isolated a cDNA clone encoding the human S3 ribosomal protein from a normal human colon cDNA library. The clone was identified as one of many that detected genes whose level of expression was increased in adenocarcinoma of the colon relative to normal colonic mucosa. Increased levels of the S3 transcript were present in the tumors of all eight patients examined. Moreover, the S3 mRNA was also more abundant in 7 of 10 adenomatous polyps, the presumed precursor of carcinoma. Additional studies demonstrated that increased levels of mRNAs encoding several other ribosomal proteins, including S6, S8, S12, L5, and P0, were present in colorectal tumors and polyps. These results suggest that there is increased synthesis of ribosomes in colorectal tumors and that this increase is an early event in colon neoplasia.

Involvement of chromosome 5 in large bowel cancer

We present here 3 of 30 cases of large bowel cancer cytogenetically studied, with deletion of chromosome 5. One of them presented a terminal deletion and the other two an interstitial deletion of chromosome 5q. In all three cases the segment 5q12-22 was deleted. Our findings may show that the segment 5q12-22 is important for a subgroup of colorectal cancers.