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| Â | Human Genetics - Chromosomal Inheritance 1 |
 | | Because Robertsonian translocation is responsible for about 9% of the Down syndrome children born to mothers under the age of 30, it is important to karyotype the child to determine if the child is the result of a Robertsonian translocation or simple meiotic nondisjunction. | | | Down syndrome mothers under the age of 30 have a relatively low recurrence risk for a second trisomy 21 if the first affected child resulted from either meiotic or mitotic nondisjunction. | | | Down syndrome, or trisomy 21, is the classic example of a human disease caused by autosomal nondisjunction where some, but not all, affected individuals do survive. |
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http://www.uic.edu/classes/bms/bms655/lesson9.html
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| Â | What is Down Syndrome? |
| | There seems to be no connection between any type of Down syndrome and parents’ activities before or during pregnancy. | | | Genetic counseling can be sought to determine the origin of the translocation. | | | Although nondisjunction can be of paternal origin, this occurs less frequently. |
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http://www.fadss.net/news.htm
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| Â | Down Syndrome |
| | Unfortunately, specific medications were not identified in this study. | | | Maternal folate polymorphisms and the etiology of human nondisjunction. | | | Risk for birth defects among premature infants: A population-based study. |
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http://www.tdh.state.tx.us/tbdmd/risk/risk3-downsyndrome.htm
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| Â | Indian Pediatrics - Editorial |
| | This study has further shown that 9 percent of cases were paternally derived (50 percent M-I, 50 percent M-II) and 5 percent were somatic in origin. | | | MTHFR polymorphism was observed in mothers of trisomy 18 conceptuses but they were unable to identify any other significant associations. | | | Funding: None for practical work except WHO fellowship to carry out review work on the subject as a part of 11th PG course in Reproductive Biology and Reproductive Medicine held at Geneva, Oct 2001. |
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http://www.indianpediatrics.net/feb2003/feb-115-123.htm
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| Â | [No title] |
| | Under the assumption that there is at most one crossover within each marker interval, we will discuss how to use our approach to recover exchange patterns during meiosis. | | | However, the valuable information from such studies has not been fully utilized by existing methods. | | | Chromosomal nondisjunction may lead to uniparental disomy (UPD) and trisomy. |
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http://genetics.faseb.org/genetics/ashg00/f213.htm
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| Â | Nondisjunction of chromosomes leading to hyperdiploid childhood B-cell precursor acute lymphoblastic leukemia is an ... |
| | From the Children's Cancer Research Institute; St Anna Kinderspital; Clinic for Blood Group Serology, University of Vienna; Landeskinderkrankenhaus Linz; and Austrian Newborn Screening Laboratory, Department of Pediatrics, University of Vienna; all of Austria. | | | We thereby provide the first evidence that nondisjunction | | | Nondisjunction of chromosomes leading to hyperdiploid childhood B-cell precursor acute lymphoblastic leukemia is an early event during leukemogenesis -- Panzer-Grümayer et al. |
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http://www.bloodjournal.org/cgi/content/full/100/1/347
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| Â | Abstract: The origin of the extra chromsome 21 |
| | Despite the clinical importance of trisomy 21, we have been ignorant of the causes of meiotic nondisjunction of chromosome 21. | | | Recently, however, genetic mapping studies of trisomy 21 families have led to the identification of the first molecular correlate of human nondisjunction; i.e. | | | Mistakes in recombination seem to increase the risk of nondisjunction. |
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http://www.ds-health.com/abst/a0004.htm
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| Â | 189: Modeling human aneuploidy: studies of a nondisjunction-prone murine chromosome. |
| | Further, it suggests that clinically relevant human mosaicism (e.g., CPM) may reflect the fact that the earliest cleavage divisions are especially vulnerable to nondisjunction. | | | Despite the clinical importance of aneuploidy, we know little of the causes of mammalian nondisjunction. | | | In initial studies, we conducted cytogenetic studies at different developmental stages to determine 1) if nondisjunction occurs in both meiosis and mitosis and 2) if nondisjunction is restricted to specific developmental stages. |
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http://genetics.faseb.org/genetics/ashg99/f189.htm
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| Â | KARYOTYPE ALTERNATIVES |
| | Although any autosome can undergo nondisjunction, only a few of these aberrations are expressed in viable offspring. | | | There can be some mental handicap due to the IQ range of 80-95 (Levitan). | | | Some have been reported for chromosome numbers 8 and 22 but these seem to be caused by nondisjunction during mitosis and thus are not expressed in all cells of the child. |
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http://www.woodrow.org/teachers/bi/1993/karyoteype.html
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| Â | Genetic Books |
| | Campbell-Lashley, Cindy, Visual Aids for Health Care Professionals, 2nd Edition 2001 | | | Genetic topics: meiosis, mitosis, patterns of inheritance, nondisjunction, monosomy, trisomy, anaphase lag, mosaicism, Lyonization, inversions and duplication/deletion syndromes, mitochondrial and multifactorial inheritance, imprinting and UPD, cancer, balanced / Robertsonian translocations, linkage analysis, metabolic disorders, twinning, Rh sensitization, amniocentesis, CVS, PUBS, confined placental mosaicism, and more. |
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http://www.kumc.edu/gec/allbooks.html
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| Â | [No title] |
| | Preliminary results in some other cases of similar aberrations disclosed further instances of mosaic-UPD evidencing that a substantial number of structural aberrations, especially in mosaic state, presumably start from meiotic nondisjunction and are formed by subsequent postzygotic structural rearrangements. | | | Recent studies, however, have shown that meiotic nondisjunction is also the first step leading to some structural chromosome aberrations, particularly to almost all cases of additional isochromosomes or isodicentric chromosomes. | | | Another example of how meiotic nondisjunction may constitute one (the first) step towards chromosomal pathology is uniparental disomy (UPD). |
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http://www.biologia.uniba.it/eca/NEWSLETTER/NS-2/2-.html
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| Â | CLOE - Co-operative Learning Object Exchange |
| | If a quiz question is incorrectly answered, a hint pops up to guide the user to the correct response. | | | A series of short quiz questions test the user's understanding of the consequences of nondisjunction happening during meiosis I as compared to meiosis II. | | | For information contact Diane Goldstein at the University of Western Ontario: dianeg@uwo.ca |
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http://cloe.on.ca/collaborationswanted.html
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| Â | Sex Chrom Abn |
| | When hormone therapy or surgery is used, the best bet is to make the | | | If nondisjunction involves the sex chromosomes, it results in eggs or sperm | | | Nondisjunction in males can lead to XX, XY, O and YY sperm. |
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http://www.tamu.edu/classes/plan/magill/gene310/SexChromosomeAbn/Sex_Chrom_Abn.html
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| Â | 273: A mammalian model for human aneuploidy: sequence divergence causes meiotic nondisjunction in female mice. |
| | Importantly, both of these phenomena are hallmarks of human nondisjunction. | | | Thus, our initial results indicate that, by using the appropriate mouse strains, nondisjunction may be increased to a level comparable to that observed in humans, providing the first useful animal model of human female nondisjunction. | | | These figures underscore the importance of identifying a mammalian model of human female nondisjunction, the source of most meiotic segregation errors. |
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http://www.faseb.org/genetics/ashg02s/f273.htm
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| Â | Clustering of Trisomy 18 in Kuwait: Genetic |
| | Hansmann I. Clustering of chromosomal aneuploidy and tracing of nondisjunction in man. Environ Health Perspect 1979;31:23-5. | | | Trisomy 18 is a well-known autosomal chromosomal disorder, giving rise to a well-defined clinical syndrome. | | | However, it seems reasonable to assume that exogenous factors could be partially responsible. |
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http://www.kfshrc.edu.sa/annals/193/98-168.html
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| Â | CMGS-Uniparental Disomy and Confined Placental Mosaicism/17.12.98 |
| | Nondisjunction is the most common mechanism for producing aneuploidy. | | | Mitotic nondisjunction is a major mechanism in the causation of mosaicism. | | | Heterodisomy describes the most common situation where nondisjunction occurs in oogenesis at the first meiotic division resulting in two different homologous chromosomes from one parent. |
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http://www.ich.ucl.ac.uk/cmgs/updcpm.htm
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| Â | Pedigree Analysis |
| | Note that a mosaic can arise by many other mechanisms involving the change in genetic information (e.g., nondisjunction during mitosis) in the course of soma development. | | | For example, most trisomies create sufficient problems with development that the fetus is rendered inviable, i.e., incapable of surviving outside of the womb and, in many cases, inside the womb as well. | | | A "disease" which usually is a consequence of nondisjunction is [PEEK] |
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http://www.mansfield.ohio-state.edu/~sabedon/biol1125.htm
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| Â | Human Genetics - Chromosomal Inheritance 2 |
| | The probability for nondisjunction is greatly increased if there is no recombination. | | | In about 1/30,000 conceptuses the zygote probably was a trisomy 15, a lethal genetic condition, and early in mitotic development one chromosome 15 was lost, restoring the embryo to the diploid state. | | | As it affects only about 1/2500 live female births, only about 2% of the recognized 45,X embryos survive to term, 98% are lost. |
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http://www.uic.edu/classes/bms/bms655/lesson10.html
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| Â | Human Chromosomal Disorders |
| | The frequency of nondisjunction is quite high in humans, but the results are usually so devastating to the growing zygote that miscarriage occurs very early in the pregnancy. | | | Down Syndrome is correlated with age of mother but can also be the result of nondisjunction of the father's chromosome 21. | | | Nondisjunction occurs when either homologues fail to separate during anaphase I of meiosis, or sister chromatids fail to separate during anaphase II. |
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http://www.biology.iupui.edu/biocourses/N100/2k2humancsomaldisorders.html
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| Â | Human Genetics |
| | Sufferers of Down's syndrome suffer mild to severe mental retardation, short stocky body type, large tongue leading to speech difficulties, and (in those who survive into middle-age), a propensity to develop Alzheimer's Disease. | | | In humans, nondisjunction is most often associated with the 21st chromosome, producing a disease known as Down's syndrome (also referred to as | | | Sex-chromosome abnormalities may also be caused by nondisjunction of one or more sex chromosomes. |
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http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookhumgen.html
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| Â | Meiotic nondisjunction - Medical Dictionary definitions of popular medical terms |
| | Meiotic nondisjunction - Medical Dictionary definitions of popular medical terms | | | MedicineNet Home > MedTerms medical dictionary A-Z List > Meiotic nondisjunction | | | Please consult your healthcare provider before beginning any course of supplementation or treatment. |
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http://www.medterms.com/script/main/art.asp?articlekey=4337
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| Â | e-Learning Session |
| | Amniocentesis uses a long needle to extract fetal cells floating in the amniotic fluid. | | | Nondisjunction can occur when homologous chromosomes fail to separate during meiosis I or when daughter chromosomes fail to separate during meiosis II. | | | Most often, Down syndrome results in three copies of chromosome 21 due to nondisjunction during gametogenesis. |
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http://www.mhhe.com/biosci/genbio/maderbiology7/student/olc/chap13-outline.mhtml
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| Â | Lab Manual Exercise #8 |
| | Nondisjunction may result in sperm that carry an extra X or an extra Y chromosome, such as XX-bearing sperm, XY-bearing sperm and YY-bearing sperm. | | | During the first and second divisions of meiosis nondisjunction can occur, as shown in the following illustration. | | | In the second and final division the chromatids of each doubled chromosome separate from each other forming the haploid gametes. |
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http://waynesword.palomar.edu/lmexer8.htm
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| Â | An Application of Molecular Genotyping in Mice |
| | Information on the parental origin as well as the number of chromosomes a given progeny carried was obtained in our analysis. | | | Microsatellite markers are simple sequence repeats within the mammalian genome that can be used for identifying disease loci, mapping genes of interest as well as studying segregation patterns related to meiotic nondisjunction. | | | We studied chromosomal segregation in relation to nondisjunction in early-gestation mouse embryos using molecular genotyping. |
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http://www.biologicalprocedures.com/bpo/arts/1/53/m53abst.htm
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| Â | Abnormal Animal Mitosis Video |
| | In this sequence, one chromosome never makes it to the equatorial plate; a condition known as nondisjunction. | | | This occurs because the chromosome fails to form a bipolar attachment to the microtubule spindle fibers--it attaches to only one side of the spindle. |
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http://www.mtholyoke.edu/courses/rfink/videopages/mitosnondis.html
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| Â | 178: Skewed XCI in women experiencing a pregnancy with meiotic nondisjunction. |
| | Alternatively, cell depletion of varied etiology during early embryonic development of these mothers could lead to extreme skewing as well as to a reduced number of ovarian follicles. | | | The second control group consisted of 93 females with no known associated genetic abnormalities. | | | Skewed XCI in women experiencing a pregnancy with meiotic nondisjunction. |
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http://www.faseb.org/genetics/ashg02s/f178.htm
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| Â | Association between nondisjunction and maternal age in meiosis-II human oocytes. |
| | Association between nondisjunction and maternal age in meiosis-II human oocytes. | | | The chromosomes in the oocyte and first polar body complement each other and provide an internal control to differentiate between aneuploidy and technical errors. | | | First, nondisjunction of bivalent chromosomes resulting in two univalents going to the same pole and, second, nondisjunction by premature chromatid separation (predivision) of univalent chromosomes producing either a balanced (2 + 2) or unbalanced (3 + 1) distribution of chromatids into the first polar body and M-II oocytes. |
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http://www.arclab.org/medlineupdates/abstract_8659524.html
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| Â | Consistent nondisjunction of B chromosomes in Black Mexican |
| | If this is true, it seems to occur only when the plant possesses a very high number of B chromosomes (at least 9 B's in the two cases presented here). | | | Preliminary cytological data from A632/BMSC-B hybrids used as pollen sources on 0B plants show 4 progeny with odd B chromosome number out of a total of 21 progeny analyzed. | | | In order to study the nature of the influence of genetic background on B chromosome nondisjunction, crosses of BMSC-B to other inbred lines must be made. |
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http://grain.jouy.inra.fr/ggpages/mgcnl/mnl/61/136staub.html
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| Â | Nondisjunction, Genetic |
| | Genetic Non-Disjunction; Genetic Nondisjunction; Non-Disjunction, Genetic; Genetic Non Disjunction; Genetic Non-Disjunctions; Genetic Nondisjunctions; Non Disjunction, Genetic; Non-Disjunctions, Genetic; Nondisjunctions, Genetic | | | The failure of homologous CHROMOSOMES or CHROMATIDS to segregate during MITOSIS or MEIOSIS with the result that one daughter cell has both of a pair of parental chromosomes or chromatids and the other has none. |
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http://medical.webends.com/kw/Nondisjunction,+Genetic
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| Â | BioTox |
| | Detection of Chemically Induced Y-Chromosomal Nondisjunction in Human Spermatozoa, Legator, M. and Kapp, R. W., Jr. | | | Analysis of Human Spermatozoa for Y Chromosomal Nondisjunction, Kapp, R. W., Jr. | | | Y Chromosomal Nondisjunction in Dibromochloropropane - Exposed Workmen, Kapp, R. W., Jr., Picciano, D. J., and Jacobsen, C. B., Mutation Research, 64, 47-51, 1979. |
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http://www.biotox.net/_wsn/page4.html
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| Â | Chapter 18: Changes in Chromosome Number |
| | – may result from higher risk of nondisjunction in older females | | | n + 1) – product of nondisjunction in haploid cell |
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http://www.sfu.ca/biology/courses/bisc202/2003chapter11aneuploid.htm
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