When most people think of DNA, they envision it as the inherited substance that has made them what they are. They also see it as something that’s sacrosanct, written in stone, enduring from cradle to grave.
As it turns out, they could be wrong. Modern science can alter the DNA sequence, and it can do this for one cell, for multiple cells, or for an entire organism. Why would one wish to make the effort, though, and what are the implications?
What Gene Therapy Involves
In human beings, two types of genetic modifications are under investigation: germline and somatic. Each involves the introduction of a gene or gene segment into cells in need of adjustment, and neither is yet out of the experimental stage.
Germline Gene Therapy
Human germline genetic modification, or HGGM, aims to correct a malfunctioning or nonfunctioning genetic component by altering the DNA of human eggs or sperm. This theoretical, untried intervention would permanently affect the genetic makeup of future generations while having no effect whatsoever on the donors.
Somatic Gene Therapy
Somatic genetic modification attempts to treat or cure medical conditions by directly targeting the DNA sequence of diseased organs or tissues at the cellular level. Since somatic genetic modification makes no changes to the patient’s eggs or sperm, these updates will affect only the recipient and not pass on to future generations.
How Gene Therapy Is Performed
The practice of gene therapy involves transmitting genetic material into the cells in question. Since direct insertion has proven ineffective, researchers must employ a vector for this purpose. Some of the most effective carriers have proven to be modified viruses that work by infecting the cell to make it more receptive by weakening its resistance.
The means of delivery can also vary. Some methods introduce the vector directly to the patient’s body either intravenously or through inoculation. Others involve removing a patient’s cells and exposing them to the vector in a test tube environment before returning them to the body.
The Future of Gene Therapy
Although still in its infancy, successful somatic gene therapy could conceivably treat or even cure such diseases as:
– Chronic granulomatous disease.
– Cystic fibrosis.
– Huntington’s disease.
– Parkinson’s disease.
– Severe combined immune deficiency.
– Sickle-cell anemia.
If successful, the introduced gene will generate a working protein that alters the structure of the DNA to correct the genetic malfunction that’s causing the problem.
While somatic gene therapy may someday routinely cure disease and rectify inherited defects, the ability of germline gene therapy to alter the DNA of future generations raises some ethical questions. The prospect of custom ordering a red-haired, brown-eyed child with an IQ of 165 might entice some future parents, but potential legal and moral objections could halt such creativity before it ever gets off the ground.