is a deviation from the normal number (numerical aberrations)or the normal shape(morphology) of chromosomes(structural aberrations).
- Origin:-
(1)Chromosomal anomalies at germ cell level.
-It originates during the formation of germ cells.
-It present in all body cells.
-It appear in karyotyping.
-It may involve Autosomes or sex chromosomes.
*Anomalies involving Autosomes may be:-:-
- Numerical e.g Down´s syndrome (click here).
- Structural e.g Wolf-Hirschhorn Syndrome (click here),Cri-du-chat syndrome (click here).
- Numerical e.g YY syndrome (click here),Klinefelter's Syndrome (click here).
- Structural e.g Turner Syndrome (click here) , Multiple X syndrome.
-It originates during the formation of somatic cells.
-It present in certain cell population.
-It doesnot appear in karyotyping(i.e normal karyotype),but appear in karyotyping of the affected cells.
-It may involve Autosomes & may be:-
- Numerical e.g polyploidy,aneuploidy.
- Structural e.g philadelphia chromosome.
-Causes:-
- Teratogens.
- Pregnancy in old age.
- Family history of Chromosomal anomalies.
*References:-
-Priciples of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g70,71,72,78.
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