Since its introduction, the potential of gene therapy has intrigued doctors and researchers around the globe. Scientific advances have allowed gene therapy to be studied as a potential treatment in genetic diseases that have lacked options or new treatment approaches.
What exactly is gene therapy?
Gene therapy is a way to treat disease at the genetic level. There are several approaches to gene therapy including:
- Turning off genes that cause problems
- Replacing defective genes with functional genes
- Adding functional genes to help do the work of a defective gene
Gene addition therapy
The goal of gene addition therapy is to insert the functional gene into the cell, with the hope that the body will make a protein it could not make adequately before, which may potentially correct the genetic deficiency.
Gene addition therapy uses a delivery system called a vector, which is a part of a virus that has been genetically modified to deliver the genes into cells. Viruses are used because of their natural ability to deliver genetic material into cells.
For approaches using the gene addition method, a functional gene can be added to cells inside (in vivo) or outside (ex vivo) the body. With in vivo gene therapy, vectors carrying the gene are inserted directly into the body. In ex vivo gene therapy, the vector is used to insert functional copies of the defective gene into the DNA of the patient’s hematopoietic stem cells (HSCs). The HSCs are first collected from a vein in the patient’s arm through a process called apheresis. Once the cells have functional copies of the defective gene, they are referred to as gene-modified cells, and returned to the patient with the hope that they will produce new cells expressing the functional therapeutic protein.
Gene therapy is being investigated to treat a variety of cancers and genetic diseases.
It is hoped that gene therapy has the potential to be used across multiple diseases for patients in need of a new treatment option.
 What is gene therapy? How does it work? FDA website. https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm589197.htm. Accessed February 21, 2018.
 Harvesting blood stem cells for transplant. PubMed Health website. https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072612/. Accessed February 21, 2018.
 Mansilla-Soto, Jorge. Cell and Gene Therapy for the Beta-Thalassemias: Advances and Prospects. Human Gene Therapy, Volume 27 Number 4. 2016. p.301