GENE THERAPY BY: SHIVANI LUTHRA and SHIVAM MAURYA Gene therapy is an experimental techniquethat uses genes to treat or prevent disease. It replaces a faulty gene or adds a new gene in an attempt tocure disease or improve body’s ability to fight diseases. Gene therapy holdspromise for treating a wide range of diseases, such as cancer, cystic fibrosis,heart disease, diabetes, hemophilia and AIDS.
Researchers are testingseveral approaches to gene therapy, including:· Replacing a mutatedgene that causes disease with a healthy copy of the gene.· Inactivating, or”knocking out,” a mutated gene that is functioning improperly.· Introducing a newgene into the body to help fight a disease.Gene therapy may be classified into two types:· SomaticIn somaticcell gene therapy (SCGT), the therapeutic genes are transferred into anycell other than a gamete, germ cell, gametocyte, or undifferentiated stem cell.
Any such modifications affect the individual patientonly, and are not inherited by offspring. SCGT focus onsevere genetic disorders, including immunodeficiencies, hemophilia, thalassaemia, and cystic fibrosis. Such singlegene disorders are good candidates for somatic cell therapy. · Germline In germline gene therapy (GGT), germcells (sperm or eggcells) are modifiedby the introduction of functional genes into their genomes. Modifying a germcell causes all the organism’s cells to contain the modified gene. The changeis therefore heritable and passed on to later generations.
The delivery of DNA into cells can beaccomplished by multiple methods. The two major classes are:· Viral methods:In order to replicate, viruses introducetheir genetic material into the host cell, tricking the host’s cellularmachinery into using it as blueprints for viral proteins. Retroviruses go a stage further by having theirgenetic material copied into the genome of the host cell. Scientists exploitthis by substituting a virus’s genetic material with therapeutic DNA. A numberof viruses have been used for human gene therapy, including retroviruses, adenoviruses, herpes simplex, vaccinia, and adeno-associated virus.· Non-viral methods:Non-viralmethods present certain advantages over viral methods, such as large scaleproduction and low host immunogenicity. However, non-viral methods initially produced lowerlevels of transfection and gene expression, and thus lower therapeutic efficacy.
Later technologyremedied this deficiency. Methods for non-viral gene therapy include the injection of naked DNA, electroporation, the gene gun, the use of oligonucleotides, lipoplexes, dendrimers, and inorganic nanoparticles. Successful cases of gene therapy: ASHANTI DESILVA: The first successful case of gene therapy occurred in the 1990s on ayoung girl named Ashanti DE Silva, a victim of the recessive metabolicdisorder, ADA deficiency, which made her immune system weak and vulnerable tonearly every virus. She lacked the ability to produce a key enzyme which wouldultimately lead to death at a young age. Her doctors took samples of her blood,treating her malfunctioning white blood cells with the genes she did not have.
They reinjected the blood back into her with the corrected genes. Thistreatment did help her to produce the enzyme but it did not help her to makehealthy cells. Today, she still has to receive repeats of her gene therapytreatment to stabilize the amount of enzyme in her blood.
RHYS JONES: He was born with X-linked SCIDS or Severe combinedimmunodeficiency, a disease that affects boys, making them lack cells in theirimmune systems. People with SCIDS have been called “bubble boys” because oftheir fragile immune systems. Because Jones had no siblings, he had to findhealthy marrow from another source. At Great Ormond Street Children’s Hospitalin Great Britain, Jones was cured. Doctors removed some of his bone marrow andused a virus to add immune system genes to the cells. They then reinserted themarrow into Jones. This treatment saved Jone’s life. Three other people have received the same genetherapy as Jones, and have been cured as well .