Question

Aneuploidy of chromosomes in human beings results in certain disorders. Draw out the possibilities of the karyotype in common disorders of this kind in human beings and its consequences in individuals.

Answer 1

Hint: Failing segregation of chromosomes resulting in a change in the number of chromosomes is called aneuploidy. It results in genetic disorders such as chromosomal disorders which can be treated only during the embryonic stage and not after that.

Step by step answer:The disorders which occur in the given case are called genetic disorders. There are two types of genetic disorders that are mendelian disorders and chromosomal disorders. These disorders are studied in pedigree analysis. In the pedigree analysis, the inheritance of a particular trait or a particular genetic disorder is represented in the family tree over generations. Mendelian disorders occur when there is an alteration or mutation in a single gene. Some of the examples are hemophilia, cystic fibrosis, sickle cell anemia, colour blindness, phenylketonuria, and thalassemia.
The chromosomal disorders are caused when there is an absence or excess or abnormal arrangement of one or more chromosomes. Examples are down’s syndrome, Klinefelter’s syndrome, turner’s syndrome, patau’s syndrome, and Edward’s syndrome.
During cell division there is a segregation of chromatids, when these chromatids fail to segregate during cell division, there is a gain or loss of chromosome(s), and this condition is called aneuploidy. Aneuploidy results in chromosomal disorders .
In Down’s syndrome, there is a gain of an extra copy of chromosome 21 therefore this results in trisomy, Hence, Down’s syndrome is called 21st trisomy. This disorder was described by Langdon Down in the year 1866. In Down’s syndrome, the affected individual’s physical, psychomotor, and mental development is retarded. The individual’s palm is broad and has a characteristic palm crease. The individual also suffers from congenital heart disease. His/her mouth is partially open with a furrowed tongue. He/she is short-statured with a small round head and broad flat face. This disorder can occur in both the sexes that are male as well as female.
Similarly in Klinefelter’s syndrome, there is a presence of an additional copy of the X-chromosome which results in a feminine development in males. The affected individual has an overall masculine development but due to feminine development, there is a development of breasts that is gynecomastia. These individuals are sterile.
In turner’s syndrome, there is a loss of an X-chromosome in females. These individuals are also sterile because their ovaries are rudimentary and they also lack secondary sexual characters.

Note: Down’s syndrome can occur in both the sexes, but Klinefelter’s syndrome can occur only in males and similarly Turner’s syndrome can occur only in females. The Karyotype of Down’s syndrome is 45 + XX or 45 + XY. The karyotype of Klinefelter’s syndrome is 44 + XXY. The karyotype of Turner’s syndrome is 44 +X0.