Human Cytogenetics Research Articles

Comments on methods and results in: Sherman et al., "Segregation analysis of balanced pericentric inversions in pedigree data".

The analysis by Sherman et al. (1986), its basis and results have been examined. The analysis relies on general methods, which may give acceptable results under the special conditions considered by the authors, but will usually produce more or less misleading results. The program POINTER (Lalouel & Morton 1981) is shown to be based partly on a chain of irrelevant arguments for the actual context. The so-called "conventional ascertainment rules" (Morton et al. 1983) are shown to produce misleading results in cases where their assumptions are not satisfied. The mean risk for unbalanced offspring is underestimated because of an erroneous ascertainment correction. The segregation frequencies are found to be different in three national samples, contrary to the claim by Sherman et al. Only a small proportion of all information available in the data has been utilized. Alternative and more appropriate models, hypotheses and procedures have been suggested. The frequent use of packages with computer programmes of standard statistical procedures in nonstandard situations with data from collaborative studies in human cytogenetics is discussed.

Chemically induced aneuploidy in mammalian cells: Mechanisms and biological significance in cancer

A growing body of evidence from human and animal cancer cytogenetics indicates that aneuploidy is an important chromosome change in carcinogenesis. Aneuploidy may be associated with a primary event of carcinogenesis in some cancers and a later change in other tumors. Evidence from in vitro cell transformation studies supports the idea that aneuploidy has a direct effect on the conversion of a normal cell to a preneoplastic or malignant cell. Induction of an aneuploid state in a preneoplastic or neoplastic cell could have any of the following four biological effects: a change in gene dosage, a change in gene balance, expression of a recessive mutation, or a change in genetic instability (which could secondarily lead to neoplasia). To understand the role of aneuploidy in carcinogenesis, cellular and molecular studies coupled with the cytogenetic studies will be required. There are a number of possible mechanisms by which chemicals might induce aneuploidy, including effects on microtubules, damage to essential elements for chromosome function (ie, centromeres, origins of replication, and telomeres), reduction in chromosome condensation or pairing, induction of chromosome interchanges, unresolved recombination structures, increased chromosome stickiness, damage to centrioles, impairment of chromosome alignment, ionic alterations during mitosis, damage to the nuclear membrane, and a physical disruption of chromosome segregation. Therefore, a number of different targets exist for chemically induced aneuploidy. Because the ability of certain chemicals to induce aneuploidy differs between mammalian cells and lower eukaryotic cells, it is important to study the mechanisms of aneuploidy induction in mammalian cells and to use mammalian cells in assays for potential aneuploidogens (chemicals that induce aneuploidy). Despite the wide use of mammalian cells for studying chemically induced mutagenesis and chromosome breakage, aneuploidy studies with mammalian cells are limited. The lack of a genetic assay with mammalian cells for aneuploidy is a serious limitation in these studies.

Cytogenetic markers in hematoproliferative disorders.

In the last decade the improvement of methods of chromosome analysis has allowed new insights into the correlation of specific chromosome changes and certain types of malignant hematologic disorders. Even if a clear-cut correlation between a certain chromosomal marker and a certain malignancy is the exception, it is well established that specific chromosome aberrations occur nonrandomly in specific tumors. Moreover, it has been shown that so-called cellular oncogenes are located on those chromosome regions which are involved in translocations and other structural chromosome abnormalities in particular malignant tumors. The significance of chromosome alterations in leukemias and lymphomas is illustrated by examples concerning well-established data, on the one hand, and findings which have still to be confirmed, on the other. This may demonstrate that human tumor cytogenetics are a dynamically and vigorously developing branch of cancer research.

A radiobiological basis for setting neutron radiation safety standards.

Present neutron standards, adopted more than 20 yr ago from a weak radiobiological data base, have been in doubt for a number of years and are currently under challenge. Moreover, recent dosimetric re-evaluations indicate that Hiroshima neutron doses may have been much lower than previously thought, suggesting that direct data for neutron-induced cancer in humans may in fact not be available. These recent developments make it urgent to determine the extent to which neutron cancer risk in man can be estimated from data that are available. Two approaches are proposed here that are anchored in particularly robust epidemiological and experimental data and appear most likely to provide reliable estimates of neutron cancer risk in man. The first approach uses gamma-ray dose-response relationships for human carcinogenesis, available from Nagasaki (Hiroshima data are also considered), together with highly characterized neutron and gamma-ray data for human cytogenetics. When tested against relevant experimental data, this approach either adequately predicts or somewhat overestimates neutron tumorigenesis (and mutagenesis) in animals. The second approach also uses the Nagasaki gamma-ray cancer data, but together with neutron RBEs from animal tumorigenesis studies. Both approaches give similar results and provide a basis for setting neutron radiation safety standards. They appear to be an improvement over previous approaches, including those that rely on highly uncertain "maximum" neutron RBEs and unnecessary extrapolations of gamma-ray data to very low doses. Results suggest that, at the presently accepted neutron dose limit of 0.5 rad/yr, the cancer mortality risk to radiation workers is not very different from accidental mortality risks to workers in various nonradiation occupations. The neutron dose estimated to produce 2.5% lifetime risk (maximum radiation-induced risk presently accepted by the ICRP and NCRP for occupational exposure) is in the range 10-156 rad; the most probable dose is 30 rad, which is not very different from 25 rad, the presently accepted lifetime dose limit for fast neutrons.

History and present status of human chromosome studies.

Until the second half of the century most advances in cytogenetics were limited to plant and invertebrate systems. Although there was great interest in mammalian and human cytogenetics, the technical difficulties encountered in making preparations prevented consistent progress. In addition to the desire to determine normal chromosome number and morphology in man and mammals, there was great interest in chromosome changes in malignancy. As early as the late 1800s pathologists observed unequal chromatin distribution in daughter tumor cells. In the early 1900s Boveri (8) developed a somatic mutation hypothesis of the origin of cancer based not on observations in cancer cells, but on his studies on sea urchin eggs. In these materials he observed unequal chromosome distributions resulting in aneuploidy and reasoned that changes such as these could play a vital role in the alteration of the cell from the normal to the malignant state. The desire to obtain the normal human karyotype that could then be compared to tumor cells was one of the main goals in studying human chromosomes. Reports from the 1700s that related soot to the scrotal cancers of chimney sweeps and the observations that had been made on induced chromosome abnormalities produced by phenols in allium meristems added to this interest (33,34). As with most discoveries the developments that permitted the determination of the human chromosome number and karyotype was not the result of a single event or breakthrough but of building on knowledge accumulated over the years by several investigators. The case of determining the human chromosome number (60) was made possible by combining four techniques. The first of these was the use of cell culture. This technique yields a higher mitotic index than most in vivo methodologies, but more important it made it possible to obtain single cell suspensions that make cells from organized tissues equivalent to cells from ascites tumors. With cells in suspension, even distribution of chemicals and solutions to all cells and manipulations of various kinds that improve the quality of the preparations are possible. The second technique was the use of colchicine to pretreat the cells. The effects of colchicine on plant chromosomes had been reported by Blakeslee and Avery (7) and also by Levan (31). By interrupting the spindle, colchicine collects mitotic figures and increases the contraction of individual chromosomes. At the time the

Mutations in Man

Physicians seem deluged with claims of mutagenicity, not only for drugs but for ubiquitous environmental agents. This volume, edited by Günter Obe from Berlin, does not attempt to provide clinical answers. It does, however, provide background data that can help physicians appreciate why simple answers to queries about mutagenicity may prove unrealistic. The 13 chapters are individually scholarly; however, the topics chosen for inclusion seem selective. Some represent background, whereas others address specific research topics. Among background topics is a review of the organization of the genome, by M. J. Evans. The principles of gene mutations are discussed by F. Vogel. Various aspects of human cytogenetics are covered by K. Sperling, I. Hansmann, and A. T. Natarajani. Adducts of DNA and DNA repair systems are reviewed as well. All these chapters may well prove useful to many physicians wishing to update their background in this area. Other chapters emphasize more

Cytogenetics in ophthalmology

The development of human clinical cytogenetics has been comparatively recent. The authors made an analytical study of chromosomes in patients presenting ocular coloboma with mental deficiency, strabismus with malformation, and other disorders in order to define the genetic aspect of these diseases. They obtained in these patients chromosomal alterations, including translocation, aneuploidies, suggesting the importance of cytogenetic analysis in eye affections even if these are considered of monogenic character.

Autologous cellular immune response to primary and metastatic human melanomas and its regulation by DR antigens expressed on tumor cells.

Evidence for heterogeneity of several biological features of human malignant melanoma (Me) like morphology, cytogenetics, oncogenes activation, antigenic expression, metastatizing capacity and procoagulant activity are briefly reviewed in an attempt to distinguish findings related to primary vs. metastatic lesions. In our own studies monoclonal antibodies were used to study expression of MHC class I, class II products and of Me-associated antigens (MAA) on primary and metastatic Me cells. High expression of class I antigens was found in a high percentage of both primary and metastatic tumors, whereas DR and MAA showed a significant variation (from 3 to 90% of cells) in expression both in primary and in metastatic Me. When autologous cell-mediated immune responses were evaluated, it was found that Me cells from primary tumors but not those from lymph node metastases were able to stimulate autologous lymphocytes to proliferate and become cytotoxic for autologous Me. Clonal analysis of cytotoxic lymphocytes was then carried out in order to see whether the lack of lymphocytes reactivity to metastatic cells was due to the absence or to a low frequency of cytotoxic cells in the unstimulated PBL. CTL clones cytotoxic for autologous Me (Auto-Me) cells were indeed isolated. Three classes of CTL clones were identified: 1) one which is cytotoxic for Auto-Me; 2) a second one which lyse Auto-Me and allogeneic Me; and 3) a third one which is cytotoxic for Auto-Me and allogeneic normal and neoplastic cells. Metastatic Me cells, however, had the ability to suppress the stimulation of autologous PBL by alloantigens or IL-2. This effect was dose-dependent and was not due to absorption of IL-2 by Me cells. Since it has been reported that Me cells express class II MHC antigens, we investigated whether there was any correlation between autologous immune responses and DR expression on Me cells. Autologous lymphocytes stimulation was found to occur only with DR+ Me cells from primary lesions, whereas metastatic cells, either DR+ or DR-, did not stimulate autologous PBL. Moreover, the suppressive effect of metastatic Me cells was associated with their expression of DR antigens. The modulation of DR antigens on Me cells by Interferon-gamma correlated positively with their suppressive capacity. Thus, it appears that primary Me can behave differently from the metastatic one in their interactions with the immune system of autologous host. These findings suggest that DR antigens on Me cells may have an important role in the regulation of autologous immune responses.

Trisomy in man.

Trisomy, occurring in at least 4% of pregnancies, is the most common chromosome abnormality in humans. The majority of trisomies are associated with single additional chromosome. The presence of an additional sex chromosome is often associated with physical, behavioral, and intellectual impairment. The presence of an additional autosome is even more serious, being associated with severe mental and physical retardation and frequently with death in infancy. This review discusses the incidence, parental origin, and etiology of human trisomy. The incidence of trisomy varies widely among different chromosomes. This variation appears to reflect a real difference in the frequency of the primary event leading to trisomy as well as in differential selection. Studies of parental origin have shown a 1st maternal meiotic division error to be the most frequent source of the additional chromosome, regardless of the chromosome involved or the maternal age. Although the magnitude of risk varies among chromosomes, increased maternal age is an important risk factor in trisomy. The incidence of trisomy 21 increases from .05% of livebirths at maternal age 20 years to over 3% of all livebirths at age 45 years. The effect of maternal age is most pronounced in double trisomies. It has been hypothesized that the relationship between increasing maternal age and trisomy is due to a gradient in the fetal ovary that affects chiasma freequency. While the basis for the maternal age effect remains unknown, it is almost certainly due to factors acting at or before conception. Epidemiologic studies suggest that maternal irradiation exposure may also lead to trisomy; however, the effective dosage level and the relationship to maternal age remain unknown. No effect of oral contraceptives, spermicides, or fertility drugs on the incidence of trisomy has been documented to date. Understanding of the mechanisms by which trisomies are produced represents a major challenge for human cytogenetics.

T.S. Hsu, The Human and Mammalian Cytogenetics. An Historical Perspective. Springer, New York/Heidelberg/Berlin 1979.

T.S. Hsu, The Human and Mammalian Cytogenetics. An Historical Perspective. Springer, New York/Heidelberg/Berlin 1979.

Preclinical toxicology studies with acyclovir: Genetic toxicity tests

Acyclovir (ACV), an antiviral drug active in the treatment of oral and genital Herpes infections, has been evaluated for mutagenic and carcinogenic potential in a battery of in vitro and in vivo short-term assays. Negative results were obtained in the following in vitro tests: Ames Salmonella, plate incorporation and preincubation modification assays; E. coli polA +/polA − DNA repair; yeast ( S. cerevisiae D4) gene conversion; Chinese hamster ovary cells (HGPRT, APRT loci and ouabain-resistance marker); L5178Y mouse lymphoma cells (HGPRT locus and ouabain-resistance marker); and C3H/10T1/2 mouse fibroblast neoplastic transformation assay. All except the last assay were performed in the presence and absence of an exogenous metabolic activation system. ACV was positive at high concentrations × exposure times in the absence of exogenous metabolic activation in the following in vitro systems and at the indicated concentrations: BALB/c-3T3 neoplastic transformation (50 μg/mL, 72 h exposure); human lymphocyte cytogenetics (250–500 μg/mL, 48 h exposure); and L5178Y mouse lymphoma cells (TK locus, 400–2400 μg/mL, 4 h exposure; predominantly small colony mutants of chromosomal origin produced). No effects were seen in vivo (mouse dominant lethal assay; rat and Chinese hamster bone marrow cytogenetics) at up to maximum tolerated doses (MTD). An unusual clastogenic effect was seen in Chinese hamsters at 5 times the MTD. Overall, positive effects were seen only at either high concentrations (≥250 μg/mL in vitro or plasma levels) or prolonged exposure (72 hr in the BALB/c-3T3 neoplastic transformation assay). These studies support the view that ACV is a chromosomal mutagen, i.e., one which causes multi-locus damage but not single gene effects. The significance of these results for the genetic risk of ACV to man is discussed.

Atlas des maladies chromosomiques

With the advent of the new banding techniques in human cytogenetics, it has become possible to detect small changes in the human karyotype that can be related to specific phenotypic manifestations. These new syndromes have been described with increasing frequency in the literature, and the permutations of physical findings in clinical diagnosis have been increased accordingly. Fortunately, the spirit of Diderot and the French encyclopedists is not dead; Jean de Grouchy and Catherine Turleau have produced in Paris, in 1982, a magnificent atlas of chromosomal abnormalities. They describe, with the use of clinical notes, illustrations, and karyotypes, the principal cytogenetic syndromes, including the known partial trisomies, monosomies, ring chromosomes, polysomies, and polyploidies, to date. In each section, the authors correlate cytogenetic data with the latest available assignments of loci on the gene map. As an example of the detail in this book, in the section on chromosome 1, three different

Use of a desktop computer in the teaching of human genetics and basic cytogenetics

Use of a desktop computer in the teaching of human genetics and basic cytogenetics

Extreme chromosome shortening resembling fragmentation induced by 2,3-dimethyl p-benzoquinone in human lymphocytes.

Environmental MutagenesisVolume 5, Issue 6 p. 923-927 Brief Communication Extreme chromosome shortening resembling fragmentation induced by 2,3-dimethyl p-benzoquinone in human lymphocytes Máximo E. Drets, Corresponding Author Máximo E. Drets Department of Medical Genetics, University of Wisconsin, MadisonDivision of Human Cytogenetics and Quantitative Microscopy, Instituto de Investigaciones Biológicas Clemente Estable, Avda. Italia 3318, Montevideo, UruguaySearch for more papers by this author Máximo E. Drets, Corresponding Author Máximo E. Drets Department of Medical Genetics, University of Wisconsin, MadisonDivision of Human Cytogenetics and Quantitative Microscopy, Instituto de Investigaciones Biológicas Clemente Estable, Avda. Italia 3318, Montevideo, UruguaySearch for more papers by this author First published: 1983 https://doi.org/10.1002/em.2860050615Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume5, Issue61983Pages 923-927 RelatedInformation

European Society of Human Genetics Abstracts from Symposium on “Human Cytogenetics”

Clinical GeneticsVolume 19, Issue 6 p. 485-547 European Society of Human Genetics Abstracts from Symposium on “Human Cytogenetics” First published: June 1981 https://doi.org/10.1111/j.1399-0004.1981.tb02070.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume19, Issue6June 1981Pages 485-547 RelatedInformation

Counterstain-enhanced chromosome banding

Chromosome staining, in which at least one member of a pair or triplet of DNA binding dyes is fluorescent whereas the others act as counterstain, is reviewed. Appropriately chosen combinations of fluorescent dyes and counterstains can be employed to enhance general chromosome banding patterns, or to induce specific regional banding patterns. Some pairs of dyes which exhibit complementary DNA binding specificity, A-T/G-C or G-C/A-T, provide enhanced definition of positive or reverse banding patterns. Dye combinations of the type A-T/A-T, that include two DNA stains with similar specificity but non-identical binding modes, produce a specific pattern of brightly fluorescent heterochromatic regions (DA-DAPI bands). In man, the method highlights the C bands of chromosomes 1, 9, 15, 16, and the Y. Certain dye triplets of the type G-C/A-T/A-T, which include two spectroscopically separated fluorescent stains with reciprocal DNA base pair binding specificities and a non-fluorescent A-T binding counterstain, can be used to highlight selectively, in the appropriate wavelength ranges, either R bands or DA-DAPI bands. Applications of these techniques in human cytogenetics are described. The potential of the new methodology for detecting and analysing specific chromosome bands is demonstrated. The mechanisms responsible for contrast enhancement and pattern induction are reviewed and their implications for chromosome structure are discussed as they relate to the banding phenomenon and to the DNA composition of chromosomes.

Human Genetics: Problems and Approaches

Drs Vogel and Motulsky have produced a massive and scholarly reference work in human genetics in part because they both spent a year at the Center for Advanced Study in the Behavioral Sciences at Stanford, Calif. Dr Vogel had published a textbook in German in 1961 and he states that parts of it were still useful for the 1979 book. The book begins with a section on the history of human genetics, a refreshing introduction that sorts out some of the politicoscientific events of the last 50 years that have molded the field. There follow chapters on human cytogenetics, the formal genetics of man, gene action, mutation, population genetics, human evolution, genetics and human behavior, and finally practical applications of human genetics and the biological future of mankind. The chapter on human cytogenetics is marred by crude sketches designed to show the main clinical features of the most frequent aneuploid

Cytogenetics and Cell Genetics

would seem that the proper responses to the questions require a multitalented counselor with access to a programmed computer terminal or membership in a large supporting team. Licensing genetic counselors implies an accredited curriculum monitored by an accredited agency. This problem is merely identified in this section, not addressed. The third section is devoted to moral, social, and legal problems in genetic counseling and does not seem to follow the other sections. Clients for genetic counseling pay for the service to reach decisions and resolve the problem. The National Genetic Diseases Act has no meaning to this clientele. Public policy relates to the greater clientele, the public. This volume is clearly required reading for professional and amateur genetic counselors. The counselor-client and physician-patient relationships are comparable in terms of outcome of poor training and experience on the part of the counselor. The genetic counselor, however, has to appreciate the relationship without the training afforded to the physician. This volume lights a large candle. Cytogenetics and Cell Genetics. Vol. 22, no. 1-6. Winnipeg Conference (1977). Fourth International Workshop on Human Gene Mapping. Basel: S. Karger AG. Pp. 730. $49.25 The classical cytogeneticists working with corn, barley, or mouse who cooperated by assigning specific chromosomes to different colleagues should get some satisfaction in this volume by noting that the human cytogeneticists have followed their example. Of course, there is one significant difference. Who could have imagined that sexual crosses would not be involved? And, who would have thought that the discovery of the parasexual cycle in the fungal speciesAspergillus nidulans would provide the theoretical foundation for assigning genes to specific chromosomes or chromosome arms? The fourth International Workshop on Human Gene Mapping has produced a volume containing two plenary presentations , 10 separate committee reports, and more than 130 short reports. The plenary presentations concern essentially classical aspects of human cytogenetics. The committee reports are linkage summaries for each chromosome . The short reports cover gene assignments to chromosomes using somatic cell hybrids of familial studies, in situ DNA-RNA hybridization, regional mapping of specific chromosomes, comparative mapping, new experimental methods, new mediods for data analysis, and a number of nonpigeonholed items. It is noteworthy that the human cytogeneticists constantly monitor gene and chromosome nomenclature in the face of rapid progress. The objectives of the international workshops is to provide a forum for the exchange of new concepts and methodologies and to keep the human cytogeneticists in touch with each other and with the "state of the art." This volume certainly meets these objectives and provides a valuable summary for those fortunate enough to have attended the workshops and for those trying to cope with a rapidly growing and worldwide literature. 504 Book Reviews ...

Book reviews

Books reviewed in this article:Human and Mammalian Cytogenetics—An Historical Perspective T.C. Hsu.Problems in Breast Parhology J. G. Azzopardi.Gynecologic and Obstetrical Pathology E. R. Novak & J. D. Woodmff.

Statistical Methods for Classification of Human Chromosomes

The basic technical facts of human cytogenetics and the laboratory methods employed in chromosome research are explained in simple terms. The main variables used to describe chromosome images are defined and discussed. Three discriminant analysis models for chromosome classification are developed: one in which each chromosome is classified in isolation, a modification in which the cell, if normal, contains 2 chromosomes of each of the 23 kinds, and a final one in which the cell is the unit of analysis instead of the chromosome. Suggestions are made to reduce the calculations involved and to take into account missing chromosomes. The problem of detection and classification of aberrative chromosomes is studied, also in relation to multiple cell analysis. Finally four relevant problems are briefly discussed: selection of metaphase spreads, selection of variables, uncertain reference classification and measurement of performance.