Gene therapy involves treating genetic disorders by replacing, altering, or supplementing a gene that is either absent or abnormal, responsible for the disease. Two types of gene therapy are:
(a) Germ Line Gene Therapy:
1. Genetically modify germ cells to correct genetic defects.
2. Introduce a normal gene into germ cells like sperm, eggs, and early embryos.
3. Allows the transmission of modified genetic information to the next generation.
4. Despite its effectiveness in treating genetic disorders, its application in humans is not preferred due to technical and ethical reasons.
(b) Somatic Cell Gene Therapy:
1. Genetically modify somatic cells to correct genetic defects.
2. Introduce healthy genes into somatic cells like bone marrow cells, hepatic cells, fibroblasts, endothelium, pulmonary epithelial cells, central nervous system, endocrine cells, and smooth muscle cells of blood vessel walls.
3. Modification of somatic cells only impacts the treated individual, and the altered chromosomes do not pass to future generations.
4. Somatic cell gene therapy is the practical option, with clinical trials already conducted for disorders such as cancer, rheumatoid arthritis, SCID, Gaucher’s disease, familial hypercholesterolemia, hemophilia, phenylketonuria, cystic fibrosis, sickle-cell anemia, Duchenne muscular dystrophy, emphysema, thalassemia, and more.