Germ-line and somatic cell therapy provide hope for sufferers of currently incurable genetic diseases, but the boundless possibilities and opportunities presented could create more problems than they solve.
Somatic cell therapy involves genetically altering the DNA in body cells affected by a (genetic) disease, so that they will function healthily. For example, this could mean a genetically engineered virus (being used as a vector to carry the DNA for a protein that the affected body fails to make correctly) is allowed to infect the epithelial cells lining the lungs and digestive tract of an individual with cystic fibrosis. The virus would insert the healthy allele into these cells, and the cells would begin to make a functional version of the protein CFTR, which they could not normally produce as a result of their genetic condition. The potential for this kind of treatment is huge – genetic diseases cannot be cured, only the symptoms treated and this form of gene therapy would enable individuals to be healthy and normal without treatment.
However, there is a downside to the somatic cell therapy, which is that these body cells can only divide so many times – not enough to last a lifetime. When stem cells replace the genetically modified cells, these will have the faulty gene still, and all the symptoms will begin to return. There is another option, which is to alter the gametes of an individual, or even an embryo, carrying a genetic disease. The individual would inherit a normal, healthy allele, which could save them form a difficult life with many medical interventions, and ensure that they only have healthy alleles to pass on to their own children.
The largest concern is for the rights of the embryo, who cannot give consent to having their DNA altered – the substance they are made of, that makes them who they are as an individual. There are also concerns that, once “corrections” for genetic diseases become normal and/or acceptable, what is to stop the progression to selecting characteristics for unborn children? Where do we draw the line between genetic diseases and simply undesirable characteristics?
Currently germ line cell therapy is illegal in the UK. Although successful trials have been done using animals (which poses its own ethical concerns) and there is no guarantee for the embryos that are altered as to whether they would survive the invasive treatment at an early stage. Further DNA damage could be caused as a result of trying to alter one undesirable gene.