Abnormal Development - Genetic: Difference between revisions
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* '''meiosis II''' - (MII) The second part of [[M#meiosis|meiosis]]. In male human [[S#spermatogenesis|spermatogenesis]], producing of four haploid cells (23 chromosomes, 1N) from the two [[H#haploid|haploid]] cells (23 chromosomes, 1N), each of the chromosomes consisting of two sister chromatids produced in [[M#meiosis I|meiosis I]]. In female human [[O#oogenesis|oogenesis]], only a single haploid cell (23 chromosomes, 1N) is produced. | * '''meiosis II''' - (MII) The second part of [[M#meiosis|meiosis]]. In male human [[S#spermatogenesis|spermatogenesis]], producing of four haploid cells (23 chromosomes, 1N) from the two [[H#haploid|haploid]] cells (23 chromosomes, 1N), each of the chromosomes consisting of two sister chromatids produced in [[M#meiosis I|meiosis I]]. In female human [[O#oogenesis|oogenesis]], only a single haploid cell (23 chromosomes, 1N) is produced. | ||
:'''Meiosis II:''' Prophase II - Metaphase II - Anaphase II - Telophase II | :'''Meiosis II:''' Prophase II - Metaphase II - Anaphase II - Telophase II | ||
* '''prometaphase''' - (Greek, ''pro'' = before) Cell division term referring to the second [[M#mitosis|mitotic]] stage, when the nuclear envelope breaks down into vesicles. Microtubules then extend from the centrosomes at the spindle poles (ends) and reach the chromosomes. This is followed by [[M#metaphase|metaphase]]. | |||
*''' prophase''' - (Greek, ''pro'' = before) Cell division term referring to the first [[M#mitosis|mitotic]] stage, when the diffusely stained chromatin resolves into discrete chromosomes, each consisting of two chromatids joined together at the centromere. | *''' prophase''' - (Greek, ''pro'' = before) Cell division term referring to the first [[M#mitosis|mitotic]] stage, when the diffusely stained chromatin resolves into discrete chromosomes, each consisting of two chromatids joined together at the centromere. | ||
* '''uniparental disomy''' - Genetic term referring to cells containing both copies of a homologous pair of chromosomes from one parent and none from the other parent. | * '''uniparental disomy''' - Genetic term referring to cells containing both copies of a homologous pair of chromosomes from one parent and none from the other parent. |
Revision as of 08:07, 25 October 2010
Introduction
This page gives a general introduction to information about genetic abnormalities their relationship to age, ethnicity and prenatal testing. In developed countries with increasing maternal age comes the increased risk of age related genetic abnormalities, such as trisomy 21.
In order to detect some genetic abnormalities many countries offer genetic screening programs that include both Maternal serum screening (MSS, for detection of Down's syndrome and neural tube defects), Embryonic and Newborn screening (for phenylketonuria (PKU), hypothyroidism, cystic fibrosis and metabolic disorders).
In terms of maternal/paternal family history, some ethnic backgrounds have been shown to have disease-associated genetic variants, though most common genetic diseases are consistent across ethnic boundaries. For example: Caucasians of northern European ancestry and cystic fibrosis (CTFR gene), Mediterranean, Asian and Far Eastern ancestry with beta-thalassaemia. (More? Genetic Abnormalities - Ethnic)
Note that the development of in vitro fertilization techniques now allows cells from early stage blastocysts to be removed and genetically analysed prior to implantation. This has raised some ethical issues relating to what parameters will be in future used in blastocyst selection.
| Cell Division - Meiosis | Cell Division - Mitosis
Some Recent Findings
Genetic Inheritance
- Inheritance Pattern images: Genetic Abnormalities | autosomal dominant | autosomal recessive | X-linked dominant (affected father) | X-Linked dominant (affected mother) | X-Linked recessive (affected father) | X-Linked recessive (carrier mother) | mitochondrial inheritance | Codominant inheritance | Genogram symbols | Genetics
References
Reviews
Articles
Search Pubmed
Search Pubmed: genetic developmental abnormality
Terms
- anaphase - (Greek, ana = up, again) Cell division term referring to the fourth mitotic stage, where the paired chromatids now separate and migrate to spindle poles. This is followed by telophase.
- Mitosis Phases: prophase - prometaphase - metaphase - anaphase - telophase
- anaphase B - Cell division term referring to the part of anaphase during which the poles of the mitotic spindle move apart. (More? Cell Division - Mitosis)
- aneuploidy - Genetic term used to describe an abnormal number of chromosomes mainly (90%) due to chromosome malsegregation mechanisms in maternal meiosis I.
- disomy - Genetic term referring to the presence of two chromosomes of a homologous pair in a cell, as in diploid. See chromosomal number genetic disorders uniparental disomy and aneuploidy. Humans have pairs usually formed by one chromosome from each parent.
- meiosis I (MI) The first part of meiosis resulting in separation of homologous chromosomes, in humans producing two haploid cells (N chromosomes, 23), a reductional division.
- Meiosis I: Prophase I - Metaphase I - Anaphase I - Telophase I
- meiosis II - (MII) The second part of meiosis. In male human spermatogenesis, producing of four haploid cells (23 chromosomes, 1N) from the two haploid cells (23 chromosomes, 1N), each of the chromosomes consisting of two sister chromatids produced in meiosis I. In female human oogenesis, only a single haploid cell (23 chromosomes, 1N) is produced.
- Meiosis II: Prophase II - Metaphase II - Anaphase II - Telophase II
- prometaphase - (Greek, pro = before) Cell division term referring to the second mitotic stage, when the nuclear envelope breaks down into vesicles. Microtubules then extend from the centrosomes at the spindle poles (ends) and reach the chromosomes. This is followed by metaphase.
- prophase - (Greek, pro = before) Cell division term referring to the first mitotic stage, when the diffusely stained chromatin resolves into discrete chromosomes, each consisting of two chromatids joined together at the centromere.
- uniparental disomy - Genetic term referring to cells containing both copies of a homologous pair of chromosomes from one parent and none from the other parent.
Glossary Links
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Cite this page: Hill, M.A. (2024, April 24) Embryology Abnormal Development - Genetic. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Abnormal_Development_-_Genetic
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G