Overview
Many hereditary diseases and characteristics are caused by chromosomal abnormalities, changes, and aberrations. Birth deformities and congenital illnesses that may occur throughout a person's lifetime are frequently caused by chromosomal abnormalities. By looking at the chromosomes' karyotypes in a sample of cells, chromosomal disorders can be found, and counseling can then be provided to parents or families whose children are at risk of developing genetic disorders.
What are Chromosomes?
Chromosomes are the body’s genetic structures that contain genes. Genes are the unique instructions that inform the body how to grow and function. They control physical and physiological characteristics including blood type, hair color, illness susceptibility, etc.
What are Chromosomal Disorders?
Although there are many kinds of chromosome disorders, generally, they can be categorized into the two following basic groups, such as:
Numerical Disorders:
Monosomy occurs when a person is missing one of the chromosomes from a pair. Trisomy is the term for when a person has greater than two chromosomes instead of a pair. A condition like Down syndrome is an example caused by numerical disorders. Trisomy 21 is another name for Down syndrome, in which disorder an individual has three copies of chromosome 21 instead of two.
An example of monosomy is Turner syndrome, in which a person is missing a chromosome. In Turner syndrome, a woman is born with only one sex chromosome, an X, and often has other issues such as being shorter than average and being unable to bear children.
Structural Disorders:
There are various ways the structure of a chromosome can be changed.
- Deletions: A section of the chromosome gets deleted or missing.
- Duplications: A part of the chromosome's section gets duplicated, adding extra genetic material.
- Translocations: This happens when a part of one chromosome is moved to another. Translocation comes in two major forms. When segments from two separate chromosomes get switched it is called reciprocal translocation. However, a Robertsonian translocation occurs when a complete chromosome attaches to another one at the centromere.
- Inversions: A chromosomal segment brakes off, turns inside out, and then reattaches. The genetic code is, therefore, reversed.
- Rings: A part of a chromosome brakes off and forms a ring or a circle. This happens with or without losing genetic materials.
How do Chromosomal Disorders happen?
Normal cell division mistakes lead to chromosomal disorders. Meiosis and Mitosis are the two different types of cell division.
• Mitosis: Mitosis produces two identical copies of the original cell. Two cells with 46 chromosomes each are created when a single cell with 46 chromosomes splits. Except for the reproductive organs, the body experiences this type of cell division throughout.
• Meiosis: Meiosis produces cells that have 23, as opposed to the typical 46, chromosomes. The reproductive organs undergo this kind of cell division, which helps develop the eggs and sperm.
Both procedures aim to produce cells with the appropriate number of chromosomes. However, mistakes in cell division can leave cells with an abnormally high or low number of copies of a particular chromosome.
A few other factors that can enhance the risk of chromosomal disorders are:
• Maternal Age: A women have all the eggs they will ever have in their lifespan when they are born. According to some scientists, the genetic makeup of the eggs might change as they get older. Compared to younger women, older women are more likely to experience chromosomal disorders during pregnancy. Paternal age, however, does not raise the chance of chromosomal disorders because men continue to create fresh sperm throughout their lifetimes.
• Environment: While there isn't any solid proof that certain environmental factors contribute to chromosomal disorders, it is still possible that the environment may contribute to the development of genetic errors.
What are some examples of Chromosomal Disorders?
Some of the most common chromosomal disorders are:
- Wolf-Hirschhorn syndrome
- Down syndrome
- Turner syndrome
- Cri du chat syndrome
- Edward's syndrome
- Patau syndrome
- Jacobsen syndrome
- Klinefelter's syndrome
- XYY syndrome and XXX syndrome
Wolf-Hirschhorn syndrome (WHS) is an exceedingly rare chromosomal condition characterized by a missing section of the short arm of chromosome 4.
Most of these illnesses, which frequently impact many body systems, are incurable. To treat or manage some of the accompanying symptoms, there might be methods available.
Chromosomes exist in pairs. The average human cell contains 23 pairs of chromosomes (46 total chromosomes). The mother contributes half, and the father contributes the other half.
In Turner's syndrome, a chromosome gets missing causing a woman to have only one X chromosome at birth and causing her to be shorter than average, unable to have children, etc.
Down syndrome, is characterized by a person having a mental disability, learning difficulties, a distinctive facial appearance, and also decreased muscular tone (hypotonia) in infancy, etc.
