The human genome encodes the instructions for all thefunctions of living systems.
It contains DNA sequences that determine thephysical and genetic characteristics of an organism. Genetic engineering is theprocess by which an organism’s genome is altered in a particular way (1).Advances in the field of genetic engineering allow for the examination of aspecific gene’s function by allowing the direct insertion, deletion, orsilencing of almost any gene in the human genome. The development of newertechniques like the CRISPR (clustered regularly interspaced short palindromicrepeats system) has allowed more accurate and effective manipulation of targetgenes (2). Genetic engineering can help provide a more precise understanding ofthe complex mechanisms of human genetic diseases, can lead to more effectivetreatments and diagnoses, and can create other genetic alterations that arebeneficial to human health.
The process of genetic engineering in humans has becomemore efficient as technology advances. The time-consuming procedures of pastgenetic engineering methods involved growing bacteria to produce a desiredprotein that was later reinserted into an organism’s genome. A plasmid wouldhave to be designed with the DNA sequence of interest. The bacteria would thenneed to be prepared to receive a transfection of the engineered plasmid. Thisprocess was also expensive, time consuming and prone to errors (2).
Incontrast, advanced methods of genetic engineering allows for the directmanipulation of the genetic sequences in the human genome. The CRISPR system isa universal system that can be used to target any site in the human genome; italso uses a standardized protein and RNA sequence that works for any targetgene. The ease and efficiency of the CRISPR system in comparison to othermethods has allowed for the examination of the function of genes in diseases(3).The CRISPR system is an advanced genetic engineeringtechnique that is precise and effective in editing any target in the humangenome. It is a universal system that can “cut” a specific gene and eitherdisrupt the genes function, or insert a new DNA sequence (4). This is differentfrom less advanced methods that can only partially eliminate a gene’s function.
A complete gene knockout can more accurately describe the gene’s functionbecause one can examine the physical and biological effects on the organism.Methods of advanced genetic engineering can be used tocompletely alter the genetic makeup of human biology and can target diseaseslike cancer. Cancer or other disease causing genes could be knocked out to haltor eliminate the progression of the disease (2). Cancer cells exhibit manymutations that help fuel their rapid growth. Similar mutations are seen in manytypes of cancer and are known as the hallmark characteristics of cancer cells.CRISPR can be used to attack cancer cells’ weaknesses by targeting theirprominent traits. One characteristic of cancer cells involves their metabolism.Cancer cells exhibit altered metabolic rates that keep up with their demand forcellular energy.
Genes that are involved with producing cellular energy can beknocked out to limit the cancer cell’s’ energy supply and consequently limitcell growth and progression (5). Another characteristic of cancer cells is howthey avoid attacks from the body’s innate immune system. A specific geneexpressed on tumor cells codes for a protein that deters the immune system fromattacking it.
The body’s innate immune system is not able to recognize themutated cancer cells as potential pathogens. The knockout of this immunesuppression gene using methods like CRISPR can allow the human immune system tobetter recognize and control cancer. Using a similar concept, a patient’simmune cells can be given mutations to help them better fight and recognizecancer. Once the immune cells are edited, they can be reinserted back into thepatient to specifically target cancer cells and help keep the cells fromproliferating (6). Inaddition to improving the effectiveness of cancer treatments, geneticengineering can help with curing disease caused by a few faulty genes. Forexample, Cystic Fibrosis (CF) is caused by a mutation in the cystic fibrosis transmembrane conductance regulator(CFTR) protein (7).
Genetic engineering can be used to remove the faultysequence and reinsert the correct one. Huntington’s disease is also caused by aspecific gene mutation known as the mutant version of the Huntingtin gene (mHTT).The correction of this faulty gene could permanently eliminate the brainpoisoning caused by Huntington’s (8).Along with the capabilities of genetic engineering tohelp cure and prevent diseases, genetic engineering can also be used for patientrecovery. CRISPR could be used to repair a damaged heart after a heart attackby activating the gene that regenerates heart muscle tissue (9). In a similarmanner, CRISPR could be used to regenerate cartilage tissue in joints andprevent chronic inflammation. Genetically engineered cells are given a genethat can fight inflammation (10).
The information about chronic inflammation and patientrecovery may not be completely reliable because the sources used are notsupported by scientific evidence and are more opinion based. The sources arehypothetical and possibly prone to bias, but provide different perspectives onadvanced genetic engineering in humans. The other sources used are peerreviewed and are credible sources that have multiple references.In addition to creating genetic alterations in humans,genetic engineering is being used to reduce infectious diseases spread bymosquitoes.
Gene drives are used to control mosquito populations and give themosquitoes mutations that create genes resistant to disease. For example,mosquitoes carrying malaria can be given a specific gene that is resistant tothe malaria pathogen. CRISPR can be used to engineer gene drives that ensurethe mosquitoes carry on their resistant genes through each generation (11). Advancedgenetic engineering can be used to correct mutated genes and introduce newgenetic sequences, but off-target mutations can cause unintended consequences. Becausethe human composed of many different sequences, the CRISPR system can cleave anoff-target DNA sequence that may differ by a few nucleotides from the intendedtarget. Off-target effects can cause genomic instability and can disrupt thefunction of normal genes (12). The mutations that are the consequences ofoff-target effects can have potentially harmful effects on humans.
Off-targeteffects could activate a gene involved in the progression of a specificdisease. To reduce off-target effects, algorithms are being developed to selectsequences with a lower chance of gene variability.Advancedgenetic engineering helps with the understanding of the complex human genome, themechanisms by which genetic diseases progress, and with the alteration of humancharacteristics. The precision and accuracy of newer methods has allowed forthe examination of the mutated genes that cause cancer and other geneticdiseases. In addition to halting the progression of genetic diseases, geneticengineering can be used for controlling infectious disease rates and recoveryrates in humans.
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