People are born to die, and it can’t be otherwise, because extinction is the price of mass-immortality.  But what can be otherwise is that people might die healthy, solely as a result of their chromosomes eroding over ten decades more or less.

We become fated at conception for some things, and acquire risks over a lifetime. A CDC scientists estimated that genetics contributed 30% to our premature death; social factors, 15%; environment, 5%, health care, 10%; and behavior, 40%.  That last figure suggests we make our own fate; the first doesn’t involve choice.

For four-year old Ashanti DeSilva, the first patient in an authorized gene therapy experiment, fate threatened. Because of a mutation in the DNA sequence of chromosome 20, her body was unable to make a “housekeeping” enzyme, adenosine deaminase, which caused her immune cells to die.  She suffered from Severe Combined Immune Deficiency, aka “the Bubble Boy Disease.”

She was constantly sick and repeatedly misdiagnosed until a sample of her blood arrived at the NIH laboratory of Dr. Michael Blaese.  The protocol for her treatment called for a recombinant virus, containing the adenosine deaminase gene and two others, to “infect” her white blood cells that had been removed from the body.  After those cells multiplied, they were infused into her blood stream on September 14, 1990.

This child, who could have died almost any time before then, has enjoyed normal health since, graduated from college, and is married.  Three years after this beginning, an adult man with a massive brain tumor underwent the first gene therapy trial for cancer.  In his case, a recombinant virus, with the thymidine kinase gene from Herpes simplex was introduced into the vascular bed where his tumor had been before surgery.  Any remaining malignant cells that took up the virus, in effect, developed cold sores, which then allowed the anti-herpes drug ganciclovir to knock out any remaining cancer.

Progress with gene therapy has been slower that its proponents have wished mainly because of uncertainties over the viral delivery method.  Consequently, researchers worked to find other means for altering genes, and currently, gene therapists are buzzing about a promising technique called “CRISPR” an acronym for an even stranger sounding “clustered regularly interspaced palindromic repeats.”

Actually, this refers to a phenomenon of bacterial immunity, where a natural process “edits” genes of invading pathogens.  In 2012, researchers began to foresee how this might be applied to editing human genetic defects by either deleting mutations or inserting restorative sequences.  A conceivable first attempt might rely on direct injection of the CRISPR molecules and an associated RNA enzyme into the natural stem cells of blood formation in bone marrow, or in the so-called “induced pluripotent stem cells” from skin or other tissue.  Small molecule drugs or nanoparticles also could be delivery vehicles.

CRISPR technology is still evolving—a dramatic example of medical innovation accelerating at an accelerating rate—as is human gene therapy.  Conceivably, fate itself may be edited.

Previous articleSelf-talk and health
Next articleCosmetic Dentistry Update: Esthetic Bonded Fillings


Comments are closed.