A Look Back at Dr. Mark Geier’s Revolutionary Breakthrough in Genetic Therapy

The advanced field of genetic engineering has perhaps made more revolutionary and impactful contributions to our understanding of human health and disease than any other in science. One of the field’s earliest and most significant breakthroughs occurred less than fifty years ago thanks to the efforts of three American scientists, whose work truly changed the way we think about treating genetic disorders.

In 1971, Dr. Mark Geier, Dr. Carl Merril and Dr. John Petricciani made a major advancement in the field of genetic engineering after successfully treating a sick cell with a healthy virus.  In an effort to find a more comprehensive cure for genetic diseases like Galactosemia, a genetic disease which prevents the body from metabolizing milk, Dr. Geier and his colleagues set out to test the effectiveness of introducing a healthy virus to a defective cell lacking a needed gene.

The Approach

Drs. Geier, Merril and Petricciani focused on the application of a healthy virus as the key to this type of genetic therapy because viruses are themselves, packages of genetic material. Many in science had long suspected that just as a virus could deteriorate and ultimately kill a cell, so too could it affect a cell positively, making it more healthy by supplying a missing gene. To test their hypothesis, Geier and his colleagues used the virus lamda bacteriophage, a virus known for its low risk of endangering humans. The lamda bacteriophage virus included an enzyme that metabolizes galactose, the enzyme absent/underrepresented in the genetic makeup of children who suffer from Galactosemia.

Dr. Geier collected and grew skin cells from a sufferer of the genetic disease and introduced it to the lamda bacteriophage virus. He and his scientific partners then discovered that the genetic material of the virus had been successfully transferred to the lab tissue cells, and was actively functioning within the cell. They then tested what would happen if glucose was introduced to the cell, and to the delight of the scientific community, observed the cell could now successfully break down the sugar. The presence of the deficient enzyme had increased, and the cell proved to be fully functioning.

The Impact

What did it all mean? Dr. Geier’s findings were significant because they ultimately showed for the first time that bacterial genetic material can function after placement within a human cell. This also reconfirmed the hypothesis that the genetic code is the same wherever found. Dr. Geier’s results also gave many increased hope that viral-mediated genetic therapy would be a viable, safer, and more accessible option for those suffering from genetic diseases. The gravity of his findings was also immediately recognized by other leading scientists of the time as a powerful research tool for comprehending genetic disease at the molecular level.

Viral-Mediated Genetic Therapy Today

Dr. Geier’s work ultimately paved the way for a new approach to genetic engineering that continues to this day. In fact, according to a recent May 2014 article in Nature Reviews Genetics, researchers are currently engineering adeno-associated viruses for clinical gene therapy. Adeno-associated viruses are small viruses with single-stranded DNA that have been proven to introduce genetic material to the 19th chromosome with extremely high accuracy. The adeno-associated virus will most likely treat muscle and eye diseases, as well as deliver genes to the brain through AAV vectors. Many consider the adeno-associated virus to possess significant potential for treating a host of genetic diseases.



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