Gene Therapy

With the advancement of medical science, several treatments have been discovered to treat deadly diseases. However, there are a few diseases that are genetic and as a result, are not easily curable. In a few such cases, the application of gene therapy has been found to be useful. 

It is an experimental technique through which healthy genes are inserted into an individual or embryo to treat disease. Gene therapy paves ways to replace faulty or mutated genes with new ones. 

To know how to define gene therapy, continue reading this article.

How does Gene Therapy Works?

There are several ways through which gene therapy works. 

• Replace a mutated gene with a healthy version of that gene. 

• Introduce a new functioning gene to fight disease.

• Inactivate a faulty gene that is causing disease. 

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This gene therapy diagram shows that first, the defective genes are spotted. Then, medical experts use healthy genes to replace faulty ones. Finally, the new gene restores the functionality of the existing cells. Some portions of DNA containing useful proteins enter the cells through the vectors. Inside the cell, DNA/genes start making useful proteins. After some time, the damaged cells heal and remove the source of the disease.  

The next segment focuses on the varied application of gene therapy. 

Different Kinds of Gene Therapy

Primarily, there are two types of gene therapy. 

• Somatic Gene Therapy 

The human body mainly consists of somatic or stem cells. This process uses healthy genes to replace damaged ones. The therapy targets the defective cells of an individual who is suffering from a disease. Somatic cells are mainly non-reproductive. That means the effects of this therapy will not transfer to the future generation. Hence, it is considered to be one of the safest applications of gene therapy. 

• Germline Gene Therapy 

This therapy targets the germ cells of the body that produce eggs or sperms. Germline gene therapy process includes the infusion of functional DNA into cells. However, the effect of this therapy can affect future generations. Therefore, the usage of this therapy is restricted in many places. For example, the European Union does not allow this process. 

Gene Therapy Application

With time, the popularity of this therapy is increasing. The application of gene therapy includes the following: 

• Effectively cures several genetic disorders. 

• Treats diseases like brain tumours, Alzheimer’s, Parkinson’s, Haemophilia, and several others. 

• Useful for the diseases that traditional medicine cannot cure.  

• Solely destroys disease-causing cells without affecting other cells. 

• Can be used on individuals, as well as embryos. 

However, this treatment has some temporal or permanent side effects too. 

Do it yourself: Make a detailed note on the harmful effects of gene therapy. 

Challenges of Gene Therapy 

• The new genes have to reach the right place. 

• On reaching the exact location, this gene has to start becoming functional. 

• The genes can cause harm if they reach the wrong cells. 

• Sometimes targeted cells stop the new genes from entering. The immune system of a body often also tries to kill the inserted gene. 

• It has to make sure that the new cells are affecting the functions of other cells. 

In short, gene therapy can be an excellent treatment option if used properly. 

Multiple Choice Questions

1. Somatic cell therapy involves…

1. Ex vivo

2. In vivo

3. Antisense

4. All of these

2. Which one of these causes a mutation in a single gene?

1. HIV

2. Colon cancer

3. Cystic Fibrosis

4. Diabetes

3. Which one helps in treating cancer?

1. In vivo

2. Ex vivo

3. Antisense

4. All of the above

4. ADA deficiency in children can be treated by?

1. Bone marrow transplantation

2. Gene therapy

3. Chemotherapy

4. Antisense therapy

Answers: 1-D), 2-C), 3-C), 4-A)

Gene Therapy Products

• Plasmid DNA - Therapeutic genes may be genetically built into circular DNA molecules and delivered to human cells.

• Viral Vectors - Several gene therapy products are generated from viruses because viruses have the inherent capacity to transport genetic material into cells. Once viruses have been engineered to lose their potential to cause infectious illness, they can be employed as vectors (vehicles) to deliver therapeutic genes into human cells.

• Bacterial Vectors - Bacteria can be altered to avoid producing infectious illness and then utilised as vectors (vehicles) to deliver therapeutic genes into human cells.

• Human gene Editing Technology - Gene editing aims to either disrupt dangerous genes or fix mutated genes.

• Patient-derived Cellular Gene Therapy Products - Cells are extracted from the patient, genetically changed (typically with the use of a viral vector), and then returned to the patient.

Disadvantages of Gene Therapy

• DNA Mutations - The new gene might be placed in the incorrect place in the DNA, resulting in dangerous DNA alterations or even cancer.

• Immune Response - The body's immune system may recognize the newly added viruses as invaders and attack them, resulting in inflammation, toxicity, and, in severe cases, organ failure.

• Viral Spread - Because viruses may impact several types of cells, it is likely that the viral vectors will infect cells other than those with altered or absent genes. If this occurs, healthy cells may be destroyed, resulting in sickness or disease, including cancer.

• Risk to Offspring - The altered DNA might have an impact on reproductive cells, such as egg cells in women and sperm cells in men. This might lead to genetic alterations in children born after the therapy.

• Reversion of the virus to its Original Form - When viruses are introduced into the body, they may regain their potential to cause disease.

• High cost

• Potential for short-term efficacy

Which Diseases does Gene Therapy Treat?

Several gene therapies have been authorised by the FDA. CAR T-cell therapy is one of the first, and it's exclusively for children and young people with B-cell acute lymphoblastic leukaemia, who have failed to respond to prior therapies. In Europe, a treatment for lipoprotein lipase deficiency, a condition in which a person is unable to break down fat molecules, was authorised as the first gene therapy in 2012. 

Another treatment for severe combined immune deficiency (also known as "bubble boy" syndrome) might be available in Europe very soon. Experiments have shown promising outcomes for a variety of additional ailments, that includes – Haemophilia. Some cause blindness, immune deficiencies, muscular dystrophy. Many more clinical studies are now underway, many of which are for uncommon diseases.