Gene Therapy

#GS-03 Science and Technology

For Prelims

Gene Therapy:

• Gene therapy is a technique which uses Gene editing for the replacement of defective genes with healthy ones in order to treat genetic disorders.
• In simple terms, it is an experimental technique through which healthy genes are inserted into an individual or embryo to treat disease.
• A viral or bacterial vector (harmless) is used to carry a corrective gene into a patient’s cells, where the gene then directs the cell to produce the proteins necessary to treat the disease.

Working of Gene Therapy:

Gene therapy can be done through the following ways.

• 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.

Types of Gene Therapy

Somatic Gene Therapy:

• In this method, therapeutic genes are transferred into the somatic cells or the stem cells of the human body which means that the effects will not be transferred into the next generation.

Germline Gene Therapy:

• The process involves introducing a healthy DNA into the cells responsible for producing reproductive cells, eggs or sperms hence effects are transferred to the next generation.
• Germline gene therapy is not legal in many places due to religious and moral reasons.

Base Editing

• A person’s genetic code contains several permutations of four bases viz., Adenine (A), Guanin (G), Cytosine (C) and Thymine (T).
• A mis-arrangement in the sequence of bases can become cancerous, the process of correcting this is known as Base editing.
• Base editing is more effective at treating blood disorders which are caused by so-called single point mutations, or when a change in a single base pair can cause terminal disease.
• The CRISPR-cas9 system is one of the most popular among these approaches.

CRISPR-cas9

• Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) is a gene editing technology. 
• This helps in replicating the natural defence mechanism in bacteria to fight virus attacks, using a special protein called Cas9.
• CRISPR-cas 9 system, uses Cas9 which acts like molecular scissors and can be made to cut a piece of DNA at a precise location.
• In the next stage a guide RNA can be used to insert a changed genetic code at the sites of incision.

Source “How gene therapy could cure cancer“