Genetic Disorder
Are color blindness and hemophilia a genetic diseases?
If both are to one of the parents, is it likely to be passed on to the next child as well?
On which chromosome are the genes for color blindness & hemophilia located?
Is there any types of color blindness & hemophilia?
We will try to understand the answers to all of these questions and many more from this post.
Insulin Hormone Class 11 & 12 Notes
Lets starts with color blindness.
Color Blindness
Color blindness is a sex linked recessive genetic disease. It is also known as Dalton’s disease.
The most common color blindness is the difficulty in understanding red and green colors.
A person suffering from this disease cannot differentiate between red and green colors; hence it is also called Red and Green color blindness.
It is transmitted from parents to their offspring and this disease is present in the child from the time of birth.
Where are the genes for color blindness?
The Defective genes responsible for color blindness are present on the ‘X’ chromosome.
Hence its genes are passed from mother to sons and from father to daughters, thus showing criss-cross inheritance.
The gene defect is due to mutation in the gene of cone cells which produces light absorbing pigments.
Why color blindness patient can’t differentiate in between red and green colour?
To recognize colors, there are three types of retinal cone cells present in the retina of our eyes, inside which different types of light-absorbing pigments are present.
These pigments absorb the wavelengths of different colors present in the light and make us perceive different colors.
Because of defective changes in the genes that make these pigments, it is difficult to make accurate predictions about red and green colors.
Sometimes the disease of color blindness arises due to defect in the nerve cells or neurons going to the eye, called optic nerves.
Types of Color Blindness
On the basis of difficulty in recognition of colors, color blindness can also be categorized into different types.
Protanopia
There is a problem in recognizing this red color; it is difficult to understand whatever shades of red are there in such a person.
Deuteranopia
In this, there is difficulty in understanding the color green, as well as there is trouble in differentiating other colors such as orange, green and brown.
Tritanopia
It is a very rare disease of color blindness in which only red and green pigments are present and blue pigments are completely absent.
Therefore, blue appears as green, yellow and orange appears as pink, while violet appears as deep red.
Trichromacy
In this, there is a problem in recognizing the three colors i.e. red, green and blue.
Monochromacy
Only black, white and gray colors are visible in this.
Is color blindness a dominant genetic disease? Why is color blindness more common in males than females?
No, because color blindness is a recessive genetic disease, its genes are present on the ‘X’ chromosome.
However, in males it is dominant, because males have only one ‘X’ chromosome.
Because of which if he carries the gene for color blindness in the ‘X’ chromosome then he will become a colorblind patient.
Therefore, because men have only one ‘X’ chromosome, this disease becomes dominant in them. For this reason, color blindness occurs more frequently in men.
Whereas females have two ‘X’ chromosomes. Therefore, unless the gene for color blindness is present in both ‘X’ chromosomes in females, the disease will not occur.
She will be a carrier female and not a colorblind patient if she has the gene for color blindness on only one ‘X’ chromosome.
But if the color blindness genes are present on both ‘X’ chromosomes in females, then she will be a patient with color blindness, which is very less likely.
As we saw in Hemophilia disease, in the same way men are more prone to this disease in color blindness.
The percentage of color blindness varies greatly between men and women.
For men, it is the maximum level with a probability of about 8%, while in women it is much less likely to be around 0.5%.
Is there any Permanent cure of color blindness?
Because it is a genetic disease, so far no permanent cure has been discovered for it.
However, for a person suffering from this disease, now some special types of lenses have been made for the eyes and some computer and mobile apps have also been developed.
Research work is also going on gene therapy, in which color blindness can be corrected by applying the right gene.
But gene therapy a completely new technique, it may be better in future and permanent treatment of this disease can be possible.
Along with this, pedigree chart analysis or family tree analysis and genetic counseling is also necessary, so that before marriage it can be seen that there is a possibility of such disease in the ancestors or in the parents.
Which test is done for the detection of color blindness?
To diagnose this disease, the Ishihara test is done, which was first developed by Shinobu Ishihara (1917), who was a professor at the University of Tokyo.
Presently, there are many more tests also available in detection of color blindness.
When is the World Color Blindness Awareness Day celebrated?
World Color Blindness Awareness Day is celebrated every year on 6th September; it is celebrated as the birthday of John Dalton, the discoverer of this disease.
Because he had first studied this disease in a scientific way and he himself was also suffering from this disease. However, his work was more focused on red-green color blindness.
Social problems in Color Blindness
There are persons who have any type of color blindness, they have to be deprived of jobs in many departments (such as in the army).
For example, in many countries, a person suffering from this disease is not given a job in plane, train and other departments.
Apart from recognizing the traffic signal, a person suffering from this disease has to face many other problems.
Hemophilia
After all, why does blood continue to bleed even after a small injury or cut?
Why doesn’t the blood clot in hemophilia disease when it is injured?
We will try to understand the answers to all of these questions and many more from this blog.
Hemophilia is a sex linked recessive genetic disorder. It is also known as Bleeder disease.
Hemophilia is also known as the Royal Disease because it was first discovered in the Royal Family of Europe.
The disease spread from Queen Victoria (1819–1901) to her offspring.
Therefore, it is transmitted from parents to their offspring and hemophilia is present in the child from the time of birth.
In this disease, even a small injury keeps bleeding continuously because the blood does not clot.
On which chromosome hemophilic gene is present?
The defective genes responsible for hemophilia are present on the ‘X’ chromosome.
Hence its genes are passed from mother to sons and from father to daughters, thus showing it is also show criss cross inheritance.
The hemophilia gene is form by a mutation in a normal gene which forms clotting factors or clotting protein.
Why Blood Clotting is affected?
Clotting factor is required for blood clotting, the genes that make it become mutated and turn into hemophilic genes, due to which the correct protein does not form and blood clot cannot be formed.
We all must have seen that a blood clot is formed in a maximum of 8 minutes and a minimum of 2 minutes when an injury occurs.
The process of blood clotting is a biochemical process that requires many proteins, enzymes and calcium ions etc.
If there is a deficiency of any of these, then the blood cannot clot.
Clotting Factors
In the case of hemophilia, two types of proteins or clotting factors are not produced, due to which the blood does not clot and there is continuous bleeding even after minor injuries.
These clotting factors are of two types.
Clotting factor-VIII
Clotting factor-IX
Is there more than one type of hemophilia?
Hemophilia is divided into two types on the basis of clotting factor
Hemophilia-A:
In this, the formation of clotting factor-VIII or AHG-Antihemophilic Protein is not possible.
Hemophilia-B:
It does not produce clotting factor-IX or (PTP) Plasma Thromboplastin Protein.
Is hemophilia a dominant genetic disease? Why hemophilia appear more frequently in males than females?
No, because hemophilia is a recessive genetic disease, its genes are present on the ‘X’ chromosome.
However, it is effective in males because they have only one ‘X’ chromosome, due to which if that ‘X’ chromosome carries the hemophilic gene, then he will become a hemophilic patient.
Therefore, because men have only one ‘X’ chromosome, this disease becomes dominant in them. For this reason, hemophilia occurs more easily in men.
Whereas females have two ‘X’ chromosomes. Therefore, unless the hemophilic gene is present in both ‘X’ chromosomes in females, the disease will not occur.
She will be a carrier of the disease and not a hemophilic patient because she has the hemophilic gene on only one ‘X’ chromosome.
But if the hemophilic gene is present on both ‘X’ chromosomes, then they will also be hemophilic patients, which is very rare.
Around every 7000 baby sons born, there is a possibility of hemophilia in one of them.
At the same time, there is a possibility of someone having hemophilia at the birth of every one crore (ten million) female baby girl.
In this way we see that it is a rare disease in females whereas it can occur more frequently in males.
Is there any Permanent cure of hemophilia?
Because there is a genetic disease here, so far no permanent cure has been discovered for it. Only in case of injury, the clotting factor is injected from outside, which stops the flow of blood.
Along with this, pedigree chart analysis for family tree analysis and genetic counseling is also necessary, so that before marriage it can be seen that there is a possibility of such disease in the ancestors or in the parents. Or there is no possibility of their coming into the children.
Conclusion:
In this disease, due to the non-clotting of blood after injury, there is continuous bleeding, which can lead to death of the person if he or she is not immediately given clotting factor in time.
Similarly in color blindness there is difficult to discriminate between red and green colour identification.
Thus we see that no accurate and permanent treatment of these disease has been found yet, but if we do genetic counseling and pedigree analysis related to this disease in time, then its effect can be avoided.
Along with this, special awareness regarding color blindness is very important.
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