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Adaptation With Beneficial Genetic Mutation
The accidental changes which occurs in the sequence of deoxyribose nucleic acids (DNA) results in mutation. Mutation occurs in the DNA of cell due to many factors like Mutagenic chemicals, radiation, viruses, transposons and also due to errors which may occur during cell division that is meiosis or replication of DNA. Many a times these are induced by organism itself by the process which is known as hyper mutation.
Mutation can be beneficial as well as harmful. The effect of change in protein sequence due to mutation may be sometimes beneficial in certain circumstances and environments. Many a times the organism has to fight against the extreme conditions (in which he lives) for his survival. And the one which is fittest survive. This fitness many a times occurs due to changes in genomic sequence and results in production of certain proteins or phenotypes which helps this mutant organism to survive in such extreme conditions as compared to its wild type. Such mutants are capable to withstand stressful environments and thus become fit for survival. Such mutation becomes common in the said population and further results in natural selection.
The very interesting example of such mutation which is beneficial is CCR5 mutation in humans. These occur with the deletion of 32 pairs. Such mutation having humans are more resistant to HIV infection and also in their heterozygotes, the onset of AIDS is delayed. Also this type of mutation occurs more in European sides. One reason for this was the resistance of these peoples to bubonic plague which occurred more in Europe than African countries. The frequency of this mutation increased within the population. With the research and development in this field, later it was suggested that the mutation in CCR5 occurred due to smallpox and may not be because of bubonic plague.
Sickle cell disease is another such example of beneficial mutation. Those with one of the alleles out of the two are particularly more resistant to malaria. The reason for this was mutation. The sickle cell disease which is a blood disorder produces abnormal substances similar to hemoglobin which are capable of oxygen carrying within the red blood cells. In sub Sahara Africa, one third of all carry this gene. In this area malaria is common and since the infestation of malarial plasmodium is avoided by cell sickling.
Another benefit of mutation is that, there is development in repair system which occurs naturally within the organism as compared to the initial repair process. It has been estimated that if the gene which is responsible for protein formation is damaged or mutated, the results is that 70 percent of the times it is harmful and rest 30 percent it is either neutral or slightly beneficial. Prevention of mutation occurs by an automatic method within the organism known as repair system.

Mutation which is non lethal increases the gene pool and also helps in increasing the variation among the population. The more the number of genetic changes happens in specified gene pool, the more reduced natural selection occurs. On the other hand, the mutations which are favorable and keeps on accumulation many a times results in changes which helps in adaptation.

One of the interesting examples of this is color of butterfly’s offspring. Many a times butterfly produces offspring’s having effect of mutations. Maximum times this mutation will have no harmful effects, but it may results in change in the color of any of the butterfly’s offspring and further it may help him to escape from the predator due to changes in color which makes it difficult for predator to recognize the prey or ironically saying mutated prey. Thus the mutation of these type results in survival of butterfly and produces its offspring’s better. With the increase in the number of such butterfly (mutated), they may become the larger percentage within their population and can survive in better way. Many a time’s beneficial mutation helps the population to increase reproductive success also. Even though mutation may be beneficial may a times, it does not mean all mutations are beneficial and therefore for the same the organism has a repair mechanism to avoid such mutations.
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Beneficial mutations that are known to exist in humans apart from the Sickle cell RBC and CCR5 mutation.

It is known that mutations take place randomly in the human as well as genomes of other organisms. In some cases, these mutations turn out to be beneficial and help the organisms to adapt to the different environmental changes and increase their survival rate. These changes may be adapted in the long run by the process of natural selection and may become the base for the survival of the fittest in future. Some of the beneficial mutations that are known to exist in humans apart from the sickle cell RBC and CCR5 mutation are as follows:

1. Reduced heart diseases: Heart disease is one of the most common diseases that has plagued the present times. Among the most common heart diseases is Atherosclerosis that involves the clogging of arteries due to deposition of cholesterol. In the transport of cholesterol in the blood stream, human beings possess HDL or High density Lipoproteins that help in the removal of cholesterol from the arteries and transportation to the liver, whereby it is ultimately excreted or reutilised. The gene for a protein called Apolipoprotein AI, one of the HDLs is present within the genome. This gene is beneficial for human beings as it prevents the deposition of cholesterol in the arteries, thereby helping in the prevention of atherosclerosis and other cardiac health diseases. Recently it has been found that in Italy, a small community of people are known to have a mutated form of this gene, which codes for a mutant version of this lipoprotein called Apolipoprotein AI-Milano or Apo-AIM. This Apo-AIM has been found to be more effective than Apo-AI in the removal of cholesterol from the cells. They have been found to dissolve the arterial plaques and even act as antioxidants to help prevent any sort of damage that may result due to inflammation that often accompanies arteriosclerosis. The presence of this mutated gene i.e. Apo-AIM has been associated with low measured HDL-cholesterol, yet it is associated with lower incidences of cardiac health diseases and lower levels of risk for heart attack and stroke in spite of reporting with high blood cholesterol values in some cases. Hence, this protein has become the target for the development of cardio protective drug and the artificially prepared form of this protein may develop in near future. A Canadian company called Sembiosys is trying to commercially produce this protein, however it will take a while before the commercialised protein is available for clinical use.

Another mutation PCSK9 has also been found to have more or less similar effect and it has been reported that people having this mutation have 88% reduced risk of cardiac diseases. It is also being targeted for the development of future drugs.

2. Increased bone density: Many genes are involved in governing the bone density in humans. One of them is the gene encoding the low-density lipoprotein-receptor-related protein 5 or LRP5. It has been found that impairment in the gene encoding this protein has been associated with the development of osteoporosis. However, recent discoveries have shown that another type of mutation associated with this gene has been found to magnify the function of the protein encoded. It was discovered accidentally when a youth belonging to a Midwest family walked away without a single fracture after being involved in a serious car accident. The X-ray of the person, as well as other family members, revealed above-average denser and stronger bones. They were found not just resistant to bone injuries but also skeletal degradation associated with old age. Only one side effect was reported in some of the members, who had bony outgrowths on the roofs of their mouths that were benign in nature. Research related to using this mutated protein in the therapeutics for osteoporosis and other skeletal diseases is going on.

Another type of mutation has been found in a recent study resulting in tetrachromatic vision.
Tetrachromatic vision: Humans have, in general, three kinds of cones that help them in color vision like all other primates, which helped them in having a survival advantage compared to other mammals having two kinds of cones. The gene coding for one kind of cone having strong response to blue color is found on the chromosome number 7. The genes coding for the other two kinds of cones having strong response to red and green colors are found on the X-chromosome, which explains the incidence of red-green color blindness in males having a single X-chromosome. A recent discovery has shown a woman, who showed the color discrimination results that may be expected of a true tetrachromat. It may be because of a mutation in the red or green cone gene, which may shift the range of colors to which it shows response resulting in four different color receptors in a woman due to the presence of two X-chromosomes. This mutation will not produce any effect on males, as only three color receptors would still be present only a different set due to the presence of one X-chromosome. However, the possible utility of this mutation in future remains to be discovered.
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