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Apr 22, 2015 · Learn how JAX designates mouse genotypes, and what “+” means in the context of inbred, mutant or transgenic strains.
- Overview
- Scientific journal articles for further reading
- For more information about how gene therapy works:
- Topics in the Gene Therapy and Other Medical Advances chapter
Gene therapy works by altering the genetic code to recover the functions of critical proteins. Proteins are the workhorses of the cell and the structural basis of the body’s tissues. The instructions for making proteins are carried in a person’s genetic code, and variants (or mutations) in this code can impact the production or function of proteins that may be critical to how the body works. Fixing or compensating for disease-causing genetic changes may recover the role of these important proteins and allow the body to function as expected.
Gene therapy can compensate for genetic alterations in a couple different ways.
•Gene transfer therapy introduces new genetic material into cells. If an altered gene causes a necessary protein to be faulty or missing, gene transfer therapy can introduce a normal copy of the gene to recover the function of the protein. Alternatively, the therapy can introduce a different gene that provides instructions for a protein that helps the cell function normally, despite the genetic alteration.
•Genome editing is a newer technique that may potentially be used for gene therapy. Instead of adding new genetic material, genome editing introduces gene-editing tools that can change the existing DNA in the cell. Genome editing technologies allow genetic material to be added, removed, or altered at precise locations in the genome. CRISPR-Cas9 is a well-known type of genome editing.
Genetic material or gene-editing tools that are inserted directly into a cell usually do not function. Instead, a carrier called a vector is genetically engineered to carry and deliver the material. Certain viruses are used as vectors because they can deliver the material by infecting the cell. The viruses are modified so they can't cause disease when used in people. Some types of virus, such as retroviruses, integrate their genetic material (including the new gene) into a chromosome in the human cell. Other viruses, such as adenoviruses, introduce their DNA into the nucleus of the cell, but the DNA is not integrated into a chromosome. Viruses can also deliver the gene-editing tools to the nucleus of the cell.
The vector can be injected or given intravenously (by IV) directly into a specific tissue in the body, where it is taken up by individual cells. Alternately, a sample of the patient's cells can be removed and exposed to the vector in a laboratory setting. The cells containing the vector are then returned to the patient. If the treatment is successful, the new gene delivered by the vector will make a functioning protein or the editing molecules will correct a DNA error and restore protein function.
Bulcha JT, Wang Y, Ma H, Tai PWL, Gao G. Viral vector platforms within the gene therapy landscape. Signal Transduct Target Ther. 2021 Feb 8;6(1):53. doi: 10.1038/s41392-021-00487-6. PMID: 33558455. Free full-text article from PubMed Central: PMC7868676.
Duan L, Ouyang K, Xu X, Xu L, Wen C, Zhou X, Qin Z, Xu Z, Sun W, Liang Y. Nanoparticle Delivery of CRISPR/Cas9 for Genome Editing. Front Genet. 2021 May 12;12:673286. doi: 10.3389/fgene.2021.673286. PubMed: 34054927. Free full-text article from PubMed Central: PMC8149999.
A new gene is inserted directly into a cell. A carrier called a vector is genetically engineered to deliver the gene. An adenovirus introduces the DNA into the nucleus of the cell, but the DNA is not integrated into a chromosome.
Credit: U.S. National Library of Medicine
Boston Children’s Hospital summarizes the evolution of gene therapy techniques.
The Genetic Science Learning Center at the University of Utah provides information about various technical aspects of gene therapy in Gene Delivery: Tools of the Trade. They also discuss other approaches to gene therapy and offer a related learning activity called Space Doctor.
The American Society of Gene and Cell Therapy offers an in-depth description of the different types of viral vectors used in gene therapy.
Penn Medicine's OncoLink describes how gene therapy works and how it is administered to patients.
The basics of nanoparticles and their use in medicine are explained in the Ask a Biologist feature from Arizona State University.
Your Genome from the Wellcome Genome campus explains the first gene therapy trial to treat a condition called severe combined immunodeficiency (SCID). It also describes other applications for gene therapy.
•What is gene therapy?
•How does gene therapy work?
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•What are the ethical issues surrounding gene therapy?
•Is gene therapy available to treat my disorder?
•What are CAR T cell therapy, RNA therapy, and other genetic therapies?
So a ‘genetic carrier’ is someone who carries a mutation in one copy of a gene, but fortunately, the paired copy of that gene is functioning fine, compensating for the changed one.
Genetic testing allows for the identification of changes in chromosomes, genes, or proteins (a genes encoded product). The results can confirm or rule out a suspected genetic condition or help determine a person’s chance of developing or passing on a genetic disorder.
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Jul 29, 2015 · For decades, genetic carrier testing has referred primarily to testing with the aim of identifying heterozygote carriers of mutations that put a mating of two carriers at a one in four risk of having a child with a disorder causing serious disability or early death.
A hereditary carrier (genetic carrier or just carrier), is a person or other organism that has inherited a recessive allele for a genetic trait or mutation but usually does not display that trait or show symptoms of the disease.
Feb 3, 2020 · Model organisms often point to the answer by offering candidate genes whose function can be tested. The potential for model organism research to speed diagnosis, mechanistic understanding, and treatment of human disease took a great leap forward with the organization of networks that connect clinicians with model organism geneticists.
