Localization of the gene for familial adenomatous polyposis on chromosome 5

Expression of membrane receptors and (proto)oncogenes during the ontogenic development and neoplastic transformation of the intestinal mucosa

The functional relationship between membrane receptors involved in signal transduction and (proto) oncogene expression has been explored during the ontogenic development and differentiation of the intestinal mucosa in man and rat. The present review develops detailed picture of the current understanding of some mechanisms underlying growth and function of normal, immortalized and cancerous intestinal epithelial cells.

Juvenile polyposis: a case with early presentation and death attributable to adenocarcinoma of the pancreas

A male child who first presented in the second year of life demonstrated all the recognized clinicopathological manifestations of juvenile polyposis with associated birth defects. Subsequent death at age 19 years from adenocarcinoma of the pancreas further broadens the recognized spectrum of possible sequelae in this disorder and is in keeping with current hypotheses of inherent cancer potential throughout the polyposis syndromes.

Do all colorectal carcinomas arise in preexisting adenomas?

In this article, the underlying nature of the adenoma is defined and evidence in support of the adenoma-carcinoma sequence is presented. Emphasis is placed on recent findings from the field of molecular biology which fortify the concept of the adenoma as a step in the evolution of large bowel cancer. Despite the considerable body of indirect evidence in support of the adenoma-carcinoma sequence, the de novo theory still has some support. Although differences between the de novo and adenoma carcinoma concept are largely semantic, the fact that infiltrating carcinoma can arise within small, flat foci of severely dysplastic epithelium (indistinguishable from carcinoma in situ) may be of considerable clinical importance. Other routes of morphogenesis exist also, but these make a relatively small contribution to the overall incidence of colorectal cancer. Even if it is accepted that the majority of colorectal cancers develop in a preexisting adenoma, the systematic removal of adenomas would pose a number of practical difficulties. First, adenomas are extremely common, particularly in populations at high risk of colorectal cancer. A second factor is the recently recognized existence of flat or depressed adenomas which may be small and difficult to visualize endoscopically. A simple screening program based on our knowledge of the evolution of colorectal cancer is outlined.

Obesity and abnormal behaviour associated with interstitial deletion of chromosome 18 (q12.2q21.1)

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Current status of tumor markers in large bowel cancer

The aim of a primary screening system is to detect premalignant lesions and carcinomas when amenable to "curative" surgery. Although a number of "classical" tumor markers have acquired potential for clinical management, none is presently adequate for presymptomatic diagnosis or screening. In colorectal carcinoma, the screening potential of carcinoembryonic antigen (CEA), the gastrointestinal-related antigen, CA19-9, and other more recently characterized "biochemical markers" is virtually nonexistent, even in patients at high risk to develop the disease. Promising new leads are beginning to emerge from somatic cell genetic and molecular biological approaches. In common with other epithelial neoplasms, perturbations in oncogene expression have been demonstrated in colorectal cancers, and probably reflect important events in malignant transformation and progression. Studies of oncogene expression have, however, not yet yielded clinically useful information. Recently, an intensive search for specific chromosomal and gene abnormalities in the hereditary colon cancer syndromes led to the location of the familial adenomatous polyposis (FAP) gene at chromosome 5q21-q22. Significant is that the loss of alleles on chromosome 5 has also been observed in the tumor cells of at least 20% of sporadic colon cancer patients. This type of association between constitutional genetic change and genetic aberration in the cells of sporadic tumors is reminiscent of other malignant diseases with a genetic component (e.g., retinoblastoma and Wilms' tumor).(ABSTRACT TRUNCATED AT 250 WORDS)

Chromosomal localization of the human gene for brain Ca2+/calmodulin-dependent protein kinase type IV

Cloned cDNAs have been identified as corresponding to a new brain Ca2+/calmodulin-dependent protein kinase. On the basis of structural and immunological features, we refer to this new kinase as CaM Kinase IV. Two cDNA clones were used to identify CaM Kinase IV: The downstream clone, lambda ICM-1, contains the sequence encoding the calmodulin-binding site and the second clone, lambda ICM-2, encodes a partial amino acid sequence similar to the catalytic domain of several known protein kinases. Within the calmodulin-binding site a stretch of 8 amino acids (and 9 of 10) is identical to the corresponding site in the subunits of CaM Kinase II. Southern blot analysis shows the CaM Kinase IV gene is single copy in the mouse and human genomes. Synteny analysis of Southern blot data of DNA from hamster--human hybrid cells shows that the gene is present in human chromosome 5. Hybridization of cDNA probes to metaphase spreads of human chromosomes indicates that the gene is most likely located within the region of bands q21 to q23 of chromosome 5.

Oncogenes and onco-suppressor genes: their involvement in cancer

We review the involvement of two groups of genes, oncogenes and onco-suppressor genes, in malignant transformation. Approximately 40 oncogenes have been described mainly through studies on retroviruses and by in vitro functional analyses such as transfection of transforming genes into 'normal' cells. Because they are more difficult to identify, only a handful of onco-suppressor genes have been described so far, but potentially they could number as many as oncogenes. Where these genes have been isolated and sequenced, they have been shown to be highly conserved among species, suggesting that these genes play an essential role in the normal cell. Although some of properties of oncogenes have been identified, we do not know in detail the role these genes play in normal cells or how genetic damage contributes to malignancy. The effect of oncogene expression on a cell depends both on the cell type and on the oncogene, and in some circumstances oncogenes act as onco-suppressor genes and vice versa. The elucidation of the mechanism of action of oncogenes and onco-suppressor genes will not only increase our understanding of these important genes but might also provide the framework for a biological approach to the treatment of cancer.

Human cancer and the food chain: an alternative etiologic perspective

Oncogenic viruses are among the known or presumed initiating agents of human cancer. Although evidence suggests that DNA and RNA oncoviruses may be acquired through multiple routes, our attention focuses chiefly on the ingestion pathway. We have two reasons for this. One is the possibility that viral as well as nonviral oncogenic amino acid sequences might be acquired at the top of the food chain. The other is that the food chain-infection hypothesis may reconcile several biological, ecological, and epidemiological phenomena. Transfection experiments suggest that the concept of infection may have to be broadened to embrace the cellular precursors of oncogenic viruses. Accumulating circumstantial evidence from viral oncology and molecular biology provides a basis for the belief that oncogenic viruses and their cellular precursors might be transmitted from animals to humans through the ingestion pathway. The possibility that such transmission may give rise to some human cancers must now be considered. The ingestion and genomic integration of food-associated DNA sequences may directly account for the increased risk of human cancer associated with an elevated intake of animal fat and protein. This paper addresses the role of infective oncogenic agents as the initiators, rather than the promoters, of cancer.

Deletion of chromosome 5q and familial adenomatous polyposis

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The role of heredity in the etiology of large bowel cancer: data from the Melbourne Colorectal Cancer Study

Family history data of colorectal cancer, heart disease, and stroke were obtained on near relatives (parents, siblings, and children) in 702 colorectal cancer cases and 710 age-/sex-matched community controls as part of a large, comprehensive, population-based epidemiological and clinicopathological study of colorectal cancer conducted in Melbourne (the Melbourne Colorectal Cancer Study). There was a statistically significant higher family history rate of colorectal cancer in cases than in controls (relative risk = 2.13; 95% confidence interval = 1.53-2.96; p less than 0.001). This family history effect was more pronounced for colon cancer than for rectal cancer and there was an earlier age of detection of colorectal cancer in those with a family history of this cancer when compared with those without such a history. Dietary risk factors for colorectal cancer, which were previously described in the Melbourne study, were separate and independent from the family history effects. It is concluded that a family history of colorectal cancer is an important indication to screen individuals for this cancer, and also that while heredity has a definite role in the etiology of colorectal cancer, this hereditary effect is either likely to be small, or else likely to be important in only a proportion (perhaps 20%) of cases.

Suppression of the neoplastic phenotype by replacement of the RB gene in human cancer cells

Mutational inactivation of the retinoblastoma susceptibility (RB) gene has been proposed as a crucial step in the formation of retinoblastoma and other types of human cancer. This hypothesis was tested by introducing, via retroviral-mediated gene transfer, a cloned RB gene into retinoblastoma or osteosarcoma cells that had inactivated endogenous RB genes. Expression of the exogenous RB gene affected cell morphology, growth rate, soft agar colony formation, and tumorigenicity in nude mice. This demonstration of suppression of the neoplastic phenotype by a single gene provides direct evidence for an essential role of the RB gene in tumorigenesis.

The map of chromosome 20

The number of gene assignments to human chromosome 20 has increased slowly until recently. Only seven genes and one fragile site were confirmed assignments to chromosome 20 at the Ninth Human Gene Mapping Workshop in September 1987 (HGM9). One fragile site, 13 additional genes, and 10 DNA sequences that identify restriction fragment length polymorphisms (RFLPs), however, were provisionally added to the map at HGM9. Five mutated genes on chromosome 20 have a relation to disease: a mutation in the adenosine deaminase gene results in a deficiency of the enzyme and severe combined immune deficiency; mutations in the gene for the growth hormone releasing factor result in some forms of dwarfism; mutations in the closely linked genes for the hormones arginine vasopressin and oxytocin and their neurophysins are probably responsible for some diabetes insipidus; and mutations in the gene that regulates both alpha-neuraminidase and beta-galactosidase activities determine galactosialidosis. The gene for the prion protein is on chromosome 20; it is related to the infectious agent of kuru, Creutzfeld-Jacob disease, and Gertsmann-Straussler syndrome, although the nature of the relationship is not completely understood. Two genes that code for tyrosine kinases are on the chromosome, SRC1 the proto-oncogene and a gene (HCK) coding for haemopoietic kinase (an src-like kinase), but no direct relation to cancer has been shown for either of these kinases. The significance of non-random loss of chromosome 20 in the malignant diseases non-lymphocytic leukaemia and polycythaemia vera is not understood. Twenty-four additional loci are assigned to the chromosome: five genes that code for binding proteins, one for a light chain of ferritin, genes for three enzymes (inosine triphosphatase, s-adenosylhomocysteine hydrolase, and sterol delta 24-reductase), one for each of a secretory protein and an opiate neuropeptide, a cell surface antigen, two fragile sites, and 10 DNA sequences (one satellite and nine unique) that detect RFLPs.

Increased formation of unintegrated viral DNA in skin fibroblasts from patients with familial polyposis coli shortly after infection with Kirsten murine sarcoma virus

Skin fibroblasts from patients with familial polyposis coli (FPC) exhibit increased frequency of morphological transformation, anchorage-independent growth, and enhanced production of viral RNA and viral particles after infection with murine sarcoma virus(murine leukemia virus), MSV(MLV). These FPC fibroblasts form greater amounts of unintegrated viral DNA as compared to normal fibroblasts during the first 4 to 24 hr after infection with Kirsten MSV(KiMLV), suggesting that increased susceptibility of FPC cells to MSV is determined at an early stage of viral transformation. Several MSV-transformed clones of both FPC and normal fibroblasts, isolated from agarose gel, were non-producers having integrated viral genome which was expressed into viral RNA and rescued by infection with MLV.

Villous adenomas and carcinoma of the duodenum in Gardner's syndrome

Patients with Gardner's syndrome are increasingly found to have polyps on routine upper gastrointestinal endoscopy, and their risk of developing periampullary carcinoma is between 3-12%. We report a 45 year old man with Gardner's syndrome who presented with periampullary carcinoma 5 years after colectomy. Review of the literature amassed another 21 cases of periampullary carcinoma in patients with Gardner's syndrome.

Hyperpigmented lesions of the retinal pigment epithelium in familial adenomatous polyposis

Ophthalmic examinations were performed on 56 patients with validated familial adenomatous polyposis (FAP) for hyperpigmented defects of the retinal pigment epithelium. Such lesions were seen bilaterally in 29 patients (52%) and unilaterally in 8 patients (14%). Of the 56 patients, 33 had one or more of the extracolonic expressions associated with Gardner syndrome. We found retinal lesions in 8 patients without any of the expressions of Gardner syndrome. No association was found between Gardner syndrome and the retinal lesions when these patients were compared to patients without any stigmata of Gardner syndrome, nor was any significant association found when each of the expressions was compared individually with the presence of the pigmented retinal lesions. The presence or absence of eye findings were seen to cluster within families. There was no association with sex. Fundus lesions are apparently a variable expression of the FAP gene and are not specifically associated with Gardner syndrome.

Genetic alterations during colorectal-tumor development

Because most colorectal carcinomas appear to arise from adenomas, studies of different stages of colorectal neoplasia may shed light on the genetic alterations involved in tumor progression. We looked for four genetic alterations (ras-gene mutations and allelic deletions of chromosomes 5, 17, and 18) in 172 colorectal-tumor specimens representing various stages of neoplastic development. The specimens consisted of 40 predominantly early-stage adenomas from 7 patients with familial adenomatous polyposis, 40 adenomas (19 without associated foci of carcinoma and 21 with such foci) from 33 patients without familial polyposis, and 92 carcinomas resected from 89 patients. We found that ras-gene mutations occurred in 58 percent of adenomas larger than 1 cm and in 47 percent of carcinomas. However, ras mutations were found in only 9 percent of adenomas under 1 cm in size. Sequences on chromosome 5 that are linked to the gene for familial adenomatous polyposis were not lost in adenomas from the patients with polyposis but were lost in 29 to 35 percent of adenomas and carcinomas, respectively, from other patients. A specific region of chromosome 18 was deleted frequently in carcinomas (73 percent) and in advanced adenomas (47 percent) but only occasionally in earlier-stage adenomas (11 to 13 percent). Chromosome 17p sequences were usually lost only in carcinomas (75 percent). The four molecular alterations accumulated in a fashion that paralleled the clinical progression of tumors. These results are consistent with a model of colorectal tumorigenesis in which the steps required for the development of cancer often involve the mutational activation of an oncogene coupled with the loss of several genes that normally suppress tumorigenesis.

Laryngeal carcinoma in a Lynch syndrome II kindred

Hereditary nonpolyposis colorectal cancer (HNPCC) accounts for about 4% to 6% of the total colorectal cancer burden. It is subdivided into Lynch syndrome I and II. Lynch syndrome I is characterized by an autosomal dominant inheritance pattern for site-specific, early onset, adenocarcinoma of the colon, with proximal predominance and an excess of synchronous and metachronous colonic cancers. Lynch syndrome II (cancer family syndrome) shows these same colon cancer characteristics, but differs in that there is an excess proclivity of other forms of cancer, particularly of the endometrium and ovary. This article documents a family that shows features of Lynch syndrome II. Unique aspects pertain to a patient who is in the direct genetic lineage (whose five brothers manifested colonic cancer), but who developed carcinoma of the uterine cervix at age 34 and laryngeal cancer at 60. The pedigree also shows uterine cervical carcinoma among other patients at genetic risk. Her son, who is a nonsmoker and nondrinker, manifested laryngeal cancer at age 31. These observations appear to add new information about tumor heterogeneity in HNPCC.

Chromosome 18 allele loss at the D18S6 locus in human colorectal carcinomas

This is the first report of chromosome 18 allele loss in colorectal carcinomas from FAP patients and concurrent allele losses on chromosomes 5 and 18 in sporadic colorectal cancer. This is based on our investigation of twenty-two colorectal carcinomas from sporadic cases and FAP patients which revealed tumor-specific allele loss of at least 44% at the D18S6 locus on chromosome 18 in informative cases. These results coupled with the tentative assignment of an HNPCC gene to chromosome 18 suggests that a gene on chromosome 18 may be involved in the etiology of some colon cancers. Possible mechanisms involving genetic changes on chromosome 18 in colon cancer are discussed in relation to tumor- or growth-suppressor genes.

Concerted nonsyntenic allelic loss in human colorectal carcinoma

Familial polyposis coli (FPC) is caused by an autosomal dominant gene on chromosome 5, and it has been proposed that colorectal cancer in the general population arises from loss or inactivation of the FPC gene, analogous to recessive tumor genes in retinoblastoma and Wilms' tumor. Since allelic loss can be erroneously scored in nonhomogeneous samples, tumor cell populations were first microdissected from 24 colorectal carcinomas, an additional nine cancers were engrafted in nude mice, and nuclei were flow-sorted from an additional two. Of 31 cancers informative for chromosome 5 markers, only 6 (19%) showed loss of heterozygosity of chromosome 5 alleles, compared to 19 of 34 (56%) on chromosome 17, and 17 of 33 (52%) on chromosome 18. Therefore, it appears that (i) FPC is a true dominant for adenomatosis but not a common recessive gene for colon cancer; and (ii) simple Mendelian models involving loss of alleles at a single locus may be inappropriate for understanding common human solid tumors.

Recessive mechanisms of malignancy

It is increasingly recognised that recessive mutations play an important role in the pathogenesis of many forms of malignancy. Some of the affected loci may prove to be recessively-activated proto-oncogenes, but others are now known to be tumorigenic solely by virtue of their loss or inactivation and therefore form a distinct and novel family of tumour genes. Preliminary evidence suggests that such genes are likely to be functionally heterogeneous and to encode molecules involved in the inhibition of cellular proliferation and/or the induction of differentiation. Their further study is likely to illuminate fundamental mechanisms of normal cellular growth and differentiation as well as having important implications for the pathogenesis and management of cancer.

Cytogenetic study of rectosigmoidal adenocarcinomas

Ten cases of primary rectosigmoidal adenocarcinoma were cytogenetically studied by G-banding technique using direct tumor cell preparations. All cases exhibited both numerical and structural chromosomal aberrations. Chromosomes commonly involved were, according to frequency, #3 and #8 (eight cases each), #1 (seven cases), #6 (six cases), and #7 (five cases). Similar or identical marker chromosomes were frequently identified, and it is noteworthy that i(8q) was found in five out of ten cases studied. The possible specificity of chromosome 8q in rectosigmoidal adenocarcinomas is discussed.

Type 2 (non-insulin-dependent) diabetes mellitus. New genetics for old nightmares

In the last five years, genetic markers for a large number of diseases have been localised using linkage analysis of DNA polymorphisms in affected families. The site of the genetic defect or defects leading to Type 2 (non-insulin-dependent) diabetes mellitus, a common illness with a major genetic component, remains unknown. This is due, at least in part, to the lack of large well-defined Type 2 diabetic pedigrees suitable for linkage analysis. There are several features of the disease which make large pedigrees difficult to find. The late age of onset of most probands means that informative older generations are often dead, while there is difficulty in detecting disease in younger generations. The diagnostic criteria for diabetes are, as yet, dependent on an arbitrary cut-off along a continuum of plasma glucose. The high prevalence of the disease may also produce problems as, in any given family, diabetogenic genes may be contributed by more than one parent. Varieties of the disease with a well-defined inheritance, such as maturity onset diabetes of youth, are more suitable for linkage analysis but might be due to defects at a different gene locus. Despite these difficulties, once large well-defined pedigrees have been found, linkage analysis using both candidate genes and random highly polymorphic markers is the strategy most likely to find genetic markers for the disease.

Pigmented ocular fundus lesions in the inherited gastrointestinal polyposis syndromes and in hereditary nonpolyposis colorectal cancer

The authors studied pigmented ocular fundus lesions in three different forms of hereditary gastrointestinal polyposis and in hereditary nonpolyposis colorectal cancer. Congenital hypertrophy of the retinal pigment epithelium (CHRPE) was present in at least one member of 23 families with Gardner's syndrome. By contrast, CHRPE was not found in three families with familial polyposis coli, four families with hereditary nonpolyposis colorectal cancer, and three families with Peutz-Jeghers syndrome. Pigmented ocular fundus lesions of the CHRPE-type appear to be specific to Gardner's syndrome among inherited diseases with gastrointestinal polyposis.

A primary map of ten DNA markers and two serological markers for human chromosome 19

We have constructed a primary map of 10 DNA and 2 protein markers for chromosome 19. Three of the markers define loci with a variable number of tandem repeats (VNTRs); 3 define genes--insulin receptor, low-density lipoprotein (LDL) receptor, and apolipoprotein CII; and 2 are classical markers for blood group antigens (Lewis and Secretor). The estimated genetic distance covered by the map is 137 cM in males and 189 cM in females. In some regions of the chromosome we found significant differences in recombination frequencies according to sex. This set of markers will be efficient for linkage studies in families segregating genetic defects and will provide anchor points for a high-resolution map of chromosome 19.

Immortalization of a human colorectal adenoma cell line by continuous in vitro passage: possible involvement of chromosome 1 in tumour progression

A non-tumorigenic epithelial cell line designated PC/AA, derived from a large pre-malignant colorectal adenoma from a patient with familial polyposis coli (also referred to as hereditary adenomatosis of the colon and rectum) has become immortal in vitro. PC/AA has been passaged in vitro continuously for over 4 years and shows no signs of senescence. At early passage, PC/AA has a normal diploid karyotype but with late passage is showing signs of progression, becoming aneuploid and displaying signs of morphological transformation. Every cell examined of late-passage PC/AA has an isochromosome (1q), and one other marker chromosome which is probably derived from an additional chromosome 8. The majority of cells examined have 48 chromosomes. Despite showing signs of progression in vitro, late-passage PC/AA has remained non-tumorigenic in athymic nude mice and retained morphological differentiation characteristics of colonic cells, in particular the ability to synthesize and secrete mucin. Two other cell lines derived from small adenomas did not become immortal in vitro and were also non-tumorigenic in athymic nude mice. The isolation of an immortal pre-malignant human epithelial cell line could prove invaluable in studies on human carcinogenesis and tumour progression. Our results, showing that only a large adenoma and no small adenomas have given rise to immortal cell lines, raise the possibility that the acquisition of in vitro immortality is associated with a relatively late stage in the adenoma-carcinoma sequence. The possible involvement of chromosome 1 in tumour progression is discussed.

The human as an experimental system in molecular genetics

There are compelling reasons for choosing to develop the human as the highest-order experimental system in genetics: an obvious social context that stirs interest, wide medical observation of the population that permits identification of an abundance of genetic defects, and our ability to perceive in the human subtle or complex variations that may not be observable in other species. Various lines of genetic inquiry that are based on research in other systems--cytogenetic analysis, biochemical studies, mapping of defective loci by linkage analysis in affected families, and in vitro techniques such as the creation of transgenic organisms--complement and enrich each other. New phenomena that would not have been predicted from investigations in other organisms have been found in humans, such as the discovery of the "giant" Duchenne muscular dystrophy gene and the identification of recessive cancer genes. Genetic research is yielding insights into human biology that are raising new possibilities for therapy and prevention of disease, as well as challenges to society in the form of ethical decisions about the appropriate application of genetic information.

Comparison of radiation-induced chromosomal damage between normal individuals and patients with familial polyposis coli

Cultured leukocytes of peripheral blood obtained from normal, healthy individuals and from patients with familial polyposis coli (FP) were exposed to 0 rads or 300 rads of 137Cs gamma radiation at G0 to compare damage in these two groups. Only cells in the first mitotic division were considered. The average chromosomal damage in the FP patients was not significantly higher than that in the normal group. The induced chromosomal damage at G0 was normally distributed in both the control and the patient groups as well as when they were combined.

Inversion of chromosome 5 long arm in region of cell growth gene cluster in hematologic disorders

Inversions of the long (q) arm of chromosome #5 are reported in five cases with hematologic disorders. Inversion of 5q with breakpoints in bands 5q13 and 5q33 was found in two cases with lymphoid malignancy and in two cases of myeloid hematologic malignancy. Because an inversion of 5q with breakpoints in 5q22 and 5q33 was also found in a case with myeloproliferative syndrome, the common denominator in these five cases was band 5q33. An extraordinary cluster of genes affecting cell growth and differentiation is present on 5q and may be altered by the chromosome rearrangement of 5q in hematologic disorders.

Natural history of colorectal cancer in hereditary nonpolyposis colorectal cancer (Lynch syndromes I and II)

Approximately 5 to 6 percent of the total colorectal cancer burden is accounted for by hereditary nonpolyposis colorectal cancer (HNPCC). Because clinical premonitory signs such as those seen in familial polyposis coli (FPC) are lacking, the clinician must recognize clinical findings and family history typical of HNPCC. The authors have described colorectal cancer expression from a survey of ten HNPCC kindreds. Kindred members with colorectal cancer differed significantly (P less than .05) from patients with sporadic colorectal cancer: 1) mean age of initial colon cancer diagnosis was 44.6 years; 2) 72.3 percent of first colon cancers were located in the right colon, and only 25 percent were in the sigmoid colon and rectum; 3) 18.1 percent had synchronous colon cancers; and 4) 24.2 percent developed metachronous colon cancer, with a risk for metachronous lesions in ten years of 40 percent. Affecteds and their first-degree relatives should undergo early intensive education and surveillance. In families with an early age of onset, colonoscopy should begin at age 25, and biannually thereafter, with fecal occult blood testing of the stool semiannually. Third-party carriers must become more responsive to the costly surveillance measures required for these otherwise healthy patients.

Close linkage of a highly polymorphic marker (D5S37) to familial adenomatous polyposis (FAP) and confirmation of FAP localization on chromosome 5q21-q22

Fifteen apparently unrelated Dutch families with familial adenomatous polyposis (FAP) also known as familial polyposis coli (FPC; McKusick No. 17510) were screened for linkage with the DNA probe C11p11 localized on chromosome 5q21-22 and previously reported to be closely linked to FAP (Bodmer et al. 1987; Leppert et al. 1987). In our study C11p11 was minimally informative, which is ascribable to its low heterozygosity in the North European populations. Of the above families, 12 were investigated also for linkage with D5S37 (DNA probe Pi227). Data from 11 of them were found to be informative and showed that FAP is closely linked to D5S37 previously localized on chromosome 5q21 (peak lod score 7.85 at a recombination fraction of 0.048 with 95% probability limits 0.005-0.145). Results discussed below indicate for the first time that the most likely location of the FAP gene is in the band 5q22 very close to 5q21, if not in the transitional zone between these two bands. The probe Pi227 recognizes 4 restriction fragment length polymorphism (RFLP) sites, exhibiting a total of 9 alleles with 24 theoretically possible haplotypes in the Dutch population. Therefore, this probe appears to have potential as a generally useful predictive marker for FAP until much closer and similarly useful markers become available.

A mapped set of DNA markers for human chromosome 17

We have developed and mapped by genetic linkage a primary set of markers for chromosome 17. The map consists of 21 loci derived from 27 probe/enzyme systems, including eight highly informative markers at loci containing a variable number of tandemly repeated DNA sequences (VNTRs). The map is continuous from the telomeric region of the short arm to the telomeric region of the long arm, covering estimated genetic distances of 218 cM in males and 279 cM in females. The average heterozygosity among all 21 loci in the population sample analyzed is 58%; 77% heterozygosity was observed among the eight VNTR markers that were highly informative. This map will make it possible to detect by linkage the location of genetic defects associated with chromosome 17 and will also provide anchor points for a high-resolution map of this chromosome.

Inheritance of human breast cancer: evidence for autosomal dominant transmission in high-risk families

Segregation analysis of breast cancer in families can provide the logical basis and the specific genetic models for mapping and identifying genes responsible for human breast cancer. Patterns of breast cancer occurrence in families were investigated by complex segregation analysis. In a sample of 1579 nuclear families ascertained through a population-based series of probands, an autosomal dominant model with a highly penetrant susceptibility allele fully explained disease clustering. From the maximum-likelihood Mendelian model, the frequency of the susceptibility allele was 0.0006 in the general population, and lifetime risk of breast cancer was 0.82 among susceptible women and 0.08 among women without the susceptibility allele. Inherited susceptibility affected only 4% of families in the sample: multiple cases of this relatively common disease occurred in other families by chance. The same genetic models, with higher gene frequency, explained disease clustering in an extended kindred at high risk of breast cancer. Evidence for a highly penetrant, autosomal dominant susceptibility allele for breast cancer in a high-risk family and the general population suggests that high-risk families can serve as models for understanding breast cancer in the population as a whole.

Multiple endocrine neoplasia type 1 gene maps to chromosome 11 and is lost in insulinoma

Multiple endocrine neoplasia type 1 (MEN-1) is a predisposition to hyperplasia of the parathyroid glands, and to hyperplasia or tumours of the anterior pituitary and the endocrine pancreas, and is inherited as an autosomal dominant trait. Here we map the MEN-1 locus to chromosome 11 by family studies, and demonstrate tight linkage with the human muscle phosphorylase gene. By comparing constitutional and tumour tissue genotypes of insulinomas from a pair of brothers who had inherited MEN-1 from their mother, we have shown that oncogenesis in these cases involves unmasking of a recessive mutation at this locus.