Describe chromosomal disorders and provide their examples.

(N/A) Chromosomal disorders are caused due to the absence,excess,or abnormal arrangement of one or more chromosomes.
Failure of segregation of chromatids during the cell division cycle results in the gain or loss of a chromosome$(s)$,a condition called $aneuploidy$. For example,Down's syndrome results in the gain of an extra copy of chromosome $21$. Similarly,Turner's syndrome results from the loss of an $X$ chromosome in human females.
Failure of cytokinesis after the telophase stage of cell division results in an increase in a whole set of chromosomes in an organism; this phenomenon is known as $polyploidy$. This condition is often seen in plants.
The total number of chromosomes in a normal human being is $46$ ($23$ pairs). Out of these,$22$ pairs are autosomes and one pair consists of sex chromosomes. Sometimes,though rarely,an additional copy of a chromosome may be included in an individual,or an individual may lack one chromosome from any pair. These situations are known as $trisomy$ or $monosomy$ of a chromosome,respectively. Such situations lead to serious consequences. Down's syndrome,Turner's syndrome,and Klinefelter's syndrome are common examples of chromosomal disorders.
$1$. $Down's$ $Syndrome$: The cause of this genetic disorder is the presence of an additional copy of chromosome number $21$ ($trisomy$ of $21$). This disorder was first described by Langdon Down $(1866)$. The affected individual is short-statured with a small round head,furrowed tongue,and partially open mouth. The palm is broad with a characteristic palm crease. Physical,psychomotor,and mental development is retarded.
$2$. $Klinefelter's$ $Syndrome$: This genetic disorder is caused due to the presence of an additional copy of the $X$-chromosome,resulting in a karyotype of $47$,$XXY$. Such an individual has overall masculine development; however,feminine development (development of breasts,i.e.,$Gynaecomastia$) is also expressed. Such individuals are sterile.
$3$. $Turner's$ $Syndrome$: This disorder is caused due to the absence of one of the $X$ chromosomes,i.e.,$45$ with $X0$. Such females are sterile as ovaries are rudimentary,besides other features including a lack of secondary sexual characters.