Question

Gene therapy can be effective in treating some genetically caused conditions. Do you feel this reflects the value of having two genes for each trait? If so why? Please explain your position.

Answer 1

Gene therapy is the method in which normal genes are introduced into a cell in place of missing or defective genes so that genetic disorders can be corrected. It is like therapeutic delivery of nucleic acids into a patient's cells as a drug to cure certain diseases. Normally vectors , like retroviruses and adenoviruses , are used for this therapy because viruses incorporate into the host genome and thus can act as a good transfer medium.

However , the complete correction of a genetic disorder or the replacement of multiple genes is not yet possible.

Since, the introduction of a single gene is sufficient to cure or prevent the genetic disorder, it seems the value of having two genes for a character is not very important here. There are two types of gene therapy depending on which type of cells are treated-- * Somatic gene therapy , which means transfer of a section of DNA to any cell of the body that does not produce sperms or eggs.

* Germline gene therapy ,which involves transfer of a section of DNA into cells that produces sperms or eggs.

In the first type, the somatic cells already have a fixed genetic make-uo and gene therapy cannot change all the cells. Still the method is effective and has shown encouraging results in the treatment of diseases like cystic fibrosis , pancreatitis etc.

In germline gene therapy, since the new genes are introduced into the germ cells , all the resulting gametes will have that gene.

Since , both the methods are effective , we can assume that introducing a single correct gene is capable of expressing itself and curing the disease.