PCR Has Proved To Be An Invaluable Technique For The Detection Of Many Genetic Diseases

PCR HAS PROVED TO BE AN INVALUABLE TECHNIQUE FOR THE DETECTION OF MANY GENETIC DISEASES
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Introduction
Almost all diseases contain a genetic component, although there is a disparity in the extent to which genes contribute to certain diseases. Nevertheless, genetic diseases are quite varied and pose a great danger to human life. Given this fact, it is still challenging to detect these diseases early enough for intervention and treatment for proper control. A genetic disease is a disease caused by an abnormality in the genetic set up of an individual. Medics have relied on less reliable methods to diagnose and identify genetic diseases among the patients. These are the family history and physical examination. Family history, for example, relies on obtaining a comprehensive history for a family so as to examine those diseases that have affected the ancestors or parents to the patient and suspect a possibility of the same disease recurring. However, it does not confirm or help in pointing out the disease. Physical examination, on the other hand, relies on actual signs or events, suggesting a genetic disease such as miscarriages and stillbirths. With the unreliability exhibited by these methods, scientists have resorted into genetic analysis for detection of genetic diseases. Genetic diseases have their origin in genes and hence study of genes will make it easy to detect. All the same, it has not been easy to analyze genes without Polymerase Chain Reaction (PCR). PCR enables a small piece of DNA segment to be amplified into millions of copies for analysis and detection of an abnormality (Diaz and Bardelli, 2014, pg. 580). As a result, PCR has proved to be an invaluable technique for the detection of many genetic diseases since it enables the development of diagnostic tests and screening using DNA segments.
PCR is the most vital scientific technology in the area of medicine in the last century. PCR is a simple and cheaper technique for duplicating DNA as compared to previous techniques, making it the best option for all biologists. PCR works with a simple fact; that the genetic material of every living organism is different and the genetic material is contained in the DNA or RNA. Human beings, being complex beings, possess unique sequences of DNA. This unique sequence facilitates the tracing of genetic material back to its origin and identifies precisely the species of the organism. To accomplish this investigation, enough amount of DNA is required, and that is where PCR comes in handy. PCR utilizes the natural function of the polymerase enzymes, which are found in all living organisms and are charged with copying genetic material, proofreading and correctly copying the material. PCR works by characterizing, analyzing, and synthesizing specific parts of DNA. It works on even those complicated mixtures to separate, identify and duplicate a particular bit of DNA or RNA obtained from any part of the body (hair, tissue specimens or blood) (Erlich2015, pg. 126).
It should be noted that through the introduction of the PCR in the late 1970s, the scientists can now study human DNA directly unlike before. They can make a detailed understanding of the genetic variations with greater precision. It is known that genes associated with the majority of the single-gene disorders are rare and it could be hard to study them. Also, most of the traits for the mutant genes are recessive and initially were not detected in people with heterozygous genotypes. However, with the PCR, the traits in the single-gene can be extracted and reproduced so that its variations and mutations studied and predicted the possibility of causing the disease when it interacts with other recessive genes. Besides, PCR has shortened the time that researchers have to take to conclude studies. For human beings, a generation would last between 20 and 40 years, after which a breeding is concluded, and the test for transmission of the gene from the parent to offspring detected. However, with PCR the copies of the gene are prepared and manipulated so that its effect on the next generations is predicted within a short time. Variations and mutations can be predicted and determine when a disease will be caused thus lay down the foundation for the prevention of the genetic disorders (Katsanisand Katsanis,2013, pg. 420).
PCR is also a predecessor to more powerful techniques for clinical genetics such as the DNA chip technology. The chip technology surveys gene expression of thousands of genes in a single experiment. It detects the mutations in a particular gene. The technology enables the medics to determine whether a gene possesses a mutation that can lead to a disease. The researcher obtains the DNA from the person's blood sample and amplifies it through PCR so as to match with a gene that contains the mutation. Also, through the chip technology, the scientists can be able to study the activity in thousands of cells with a similar gene and be able to understand the complex relationships and impact of gene activity on the cells. This can help in detecting the impact of a gene on the entire body cells (Ladetto et al., 2014, pg. 1299).
PCR contributes towards detection of various genetic diseases in many ways. One way is through rapid and economical detection of carriers of genetic diseases. Through electrophoresis, the amplified DNA is studied to identify the normal and the carrier organisms. In an electrophoresis field, organisms with a normal genetic material will have two short segments which have resulted from cutting off the amplified DNA. An organism with affected genes or homozygous recessive will exhibit one long uncut segment since mutation prevents cutting of that segment. Thus, through amplifying DNA, medics can identify individuals who are carriers of a given genetic disorder and advise them not to marry one another. This is because carriers of such recessive genes do not suffer from the diseases, but when two carriers mate; they will give rise to an offspring whose genes express the physical characteristics of the disease. This mostly occurs in autosomal recessive diseases. Screening of couples for gene disorders before marriage acts as a preventive measure against the expression of diseases in the first and subsequent generations where the parents are carriers. Thus, PCR plays an important role in the amplification of genetic material to be used in electrophoresis for identifying recessive genes for disease among the carriers (Xiong et al., 2015, pg. 1023).
Cystic fibrosis (CF) is an example of life-threatening genetic disorder inherited among the offsprings where both parents are the carriers of the disease. CF is a disorder that causes the body to produce sticky mucus, which affects the lungs and the pancreas through blockages and clogging of the walls. Infections in these organs lead to lethal damages. The gene that causes CF manufactures a protein charged to transfer of salt in and out of the body cells. The genes are called the Cystic Fibrosis Transmembrane Regulator (CFTR). CFTR is found in chromosome seven, but CF occurs as a recessive condition. This means that for an offspring to be affected, both parents have the recessive gene CFTR. Prenatal screening, as well as screening for parents, is helpful in dealing with CF. For prenatal, a small sample of blood is taken and DNA extracted. The DNA is then amplified by PCR so as to make many copies for probing. For partners who do not have the disease, screening for CF is done to ascertain whether they carry the faulty gene. When one of the partners is a carrier while the other one is not, there is no risk of giving birth to offspring with the disease. However, if both partners are the carriers, it means the offspring will exhibit the disease and can be advised not to marry one another. Through the screening, CFTR is detected, and the possibility of the disease occurring is predicted, hence prevented through counseling of partners before marriage (Erlich2015, pg. 126).
Furthermore, PCR facilitates the study of mutations that are responsible for genetic disorders. PCR is applied in characterizing heterozygous deletions or insertions. Through PCR, the scientists can undertake sequence analysis for interrogation of the bases embedded in a gene so as to detect point mutations, where small deletions and inserti...