Question

How do doctors and researchers decide whether a disease is a good candidate for gene therapy? what are the advantages and disadvantages of using viral vectors for gene therapy? what factors must be considered when choosing a vector for a gene therapy trial? a young boy suffers from neurofibromatosis type 1 (nf1), a genetic nervous system disorder that causes tumors to grow around nerve cells. the gene for nf1, approximately 8,400 base pairs long, is located on chromosome 11. what is the best candidate for a vector for gene therapy in this case? provide evidence from your research to support your choice. how does traditional gene therapy compare to the crispr-cas9 genome editing system? genome editing has many advantages for treating and preventing diseases, however there are many ethical concerns. explain one ethical concern related to genome editing. many athletes and administrators fear the widespread use of gene doping—the use of gene therapy to modify genes that improve athletic performance. describe at least two genetic modifications that would improve the performance of an athlete. make sure to mention the body system(s) affected as well as the specific goal of the therapy. explain how gene therapy can impact the future of humans as it relates to curing diseases and gene selection?

Answer 1

Diseases that are best candidates for gene therapy are those whose disorder has been identified to be a malfunctioning gene and the biology of the gene is well known.  Gene therapy is also viable where the proper gene can be correctly delivered and replace the malfunctioned one.

The advantage of using viruses in gene theory is their effectiveness in delivering the desired gene by tapping into their natural mechanisms of infection.  However, disadvantages include the risks of affecting healthy cells while targeting sick cells and wrong placement of the desired gene hence causing undesirable mutations in DNA.

One factor is the length of the DNA that is required to be replaced through gene therapy. Most vectors have a maximum length of DNA that they can carry for effective transduction.  Another is the range of cell types that the vector can infect and the risk of immune response/ allergic reaction/ side effects.

The best vectors are herpes or vaccinia viruses.  The viruses are able to infect non-dividing cells such as the nerve cell. The vectors can accommodate 8400 bp in their genome and the transgene expressions have the potential to last long.

Traditional gene editing techniques such as TALENS and ZFN use modular proteins that target nucleotide sequences. In the CRISPR tool, the Cas9 protein is steered by a guide RNA (which is a complementary sequence to the target sequence) to the target region.

One ethical issue of gene editing is its use in genetic enhancement to develop ‘designer babies’.  The question of who should decide on whether a trait is bad or good also complicates this matter. The morality of artificiality enhancing attributes such as strength, athletic capability, intelligence, and etcetera could lead to an unhealthy ‘arms race’  between humans.

In sports doping, gene editing could be used to enhance genes that enhance muscle strength by targeting myostatin (MSTN) and GF-1 genes. Genes that promote quick break down of lactic acid and increases oxygen capacity of the lungs and blood such as EPO gene could be targets of sports doping.

Gene editing will treat diseases and disorders by repairing the causative defective gene. This is already applicable in cystic fibrosis. Artificial gene selection will be common in future thanks to gene editing.  Future humans will, therefore, have ‘desirable traits’  or new traits depending on what is appealing to the society.