Genome Editing for Heritable Genes Could be a Reality

Highlights:

Gene therapy is currently used for the treatment of non-hereditary diseases
Genetic alteration of genes controlling hereditary characters is currently not allowed by the United States and several other countries
Experts have laid down guidelines for the possible use of genome editing in the treatment of hereditary genetic disorders in the future

The National Academy of Sciences and the National Academy of Medicine convened a committee to outline criteria that should be met before allowing for clinical trials involving editing of human heritable genes. The report was published as Human Gene Editing: Scientific, Medical and Ethical Considerations.

Genome editing enable scientists to remove or add genes or alter the genome of an individual. This allows the treatment of diseases that are determined by certain genes. Several methods are available for genetic editing, the most recent being CRISPR/Cas9 system.

Human genome editing is currently being tested in clinical trials only for treatment of genetic diseases that are not inherited. One of the conditions that is being evaluated is the treatment of advanced cancer in patients who do not respond to radiotherapy or chemotherapy. Gene therapy is also being tried out in conditions like hemophilia B and mucopolysaccharidosis I. It is being tried out for the prevention and treatment of disease and disability in which the benefit extends only to the individual undergoing the treatment and does not affect subsequent generations. As of now, it is not used for enhancements of physical or mental abilities.

‘Genetic modification of hereditary genes could soon be a reality!’

The ethical implications of genome editing to edit heritable genes are much more complex. The side effects of this technique, if any, could extend through generations. On the other hand, once people realize it's benefit, there is always a risk that it could be misused for improving one's looks, or even producing "perfect" babies.

At the same time, the beneficial implications of genome editing of hereditary genes cannot be ignored. If parents have defective genes that can result in a serious disease in the baby, it can save several generations from diseases that could be traumatic for the patient as well as the families, and allows the baby to live a normal life. Therefore, experts from the National Academy of Sciences and the National Academy of Medicine put down criteria that would be required before clinical trials on genome editing of hereditary genes can be allowed.

The genome editing of heritable genes will have to be done in the sperm, ovary or the early embryo or the precursor cells. There is still some time before it can enter clinical trials. Some of the suggestions put forth by the experts regarding clinical trials for editing hereditary genes are:

It should be done for genetic disorders for which no other reasonable alternatives are available for their treatment
It should be used only for serious genetic conditions that have been proved without a doubt to be caused by the genetic defect. Adequate oversight mechanisms should be available to make sure that it does not extend to non-serious conditions. It should not be used for enhancements at present time, and public input and discussion would be needed before it is allowed.
There should be credible preclinical and /or clinical data to prove it's benefits and also find out the risks
There should be a follow-up over multiple generations, since it will have implications in the successive generations
There should be continuous assessments of the health as well as the social aspects along with inputs from public

The experts also advise that adequate transparency should be maintained and be available to patients, their families and other persons involved in the process. At the same time, the dignity of the person should be recognized and their decisions should be respected.

Though there may come a time when gene editing may be used or misused to achieve physical or mental perfection, it must be remembered that everything need not be perfect. In fact, the imperfectness in the world is what makes it more varied and beautiful.

Reference :

With Stringent Oversight, Heritable Germline Editing Clinical Trials Could One Day Be Permitted for Serious Conditions; Non-Heritable Clinical Trials Should Be Limited to Treating or Preventing Disease or Disability at This Time - (http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=24623)

Source: Medindia

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