By PROFESSOR NORBERT HERZOG and DAVID NIESEL
The word mutation doesn’t have the best reputation — most people think of the army of mutants featured in X-Men and other science fiction. There is some basis for the uniformly negative connotation: genetic mutations cause cancer, mutations in bacteria cause antibiotic resistance and many human diseases like cystic fibrosis and sickle cell anemia are the result of mutations in just a single gene. But that doesn’t mean mutations can’t be good for us too.
A mutation is a change in your DNA sequence, altering your genetic code. We are all born with some genetic mutations, which we inherit from our parents. We also acquire genetic mutations from our lifestyles. For example, exposure to UV or other types of radiation can cause changes in your DNA. Some mutations even occur as mistakes during the normal duplication of your DNA as cells divide. Since we have two copies of each of our genes, we can often tolerate one bad or mutated gene — most genetic diseases require two bad copies of the gene to cause symptoms.
One clearly positive effect of mutations is they lead to genetic diversity, which is overall good for our species. Certain genetic mutations can have very positive effects on the individuals who carry them. For example, a mutation in the CCR5 receptor gene may protect people from infection with HIV. One popular theory is that Northern Europeans with this mutation survived the Black Plague in the middle ages and have passed this gene on to subsequent generations, a true example of evolutionary selection.
Mutations that protect people from some types of heart disease, Alzheimer’s and Type 2 diabetes are getting scientists’ attention. There is important information to be gained by studying people who are resistant to different diseases. This is different from past studies, which aimed to find the disease-causing genes and then investigated ways to repair or replace these deficits. While we have made great progress in identifying genes that cause disease, we have not been as successful in devising ways to directly fix them.
New research is now focused on identifying reasons why symptoms of genetic diseases don’t show up in some people with mutated genes. In families that have many members affected by a genetic disease, there are occasionally some members who never develop the disease even though they carry the same disease-causing gene. One explanation is that a second mutation negates the disease-causing gene. Other genetic alterations have already been identified that can partially protect people from disease. Hopefully, we will identify more of these compensatory mutations and understand how they block the disease process. It is not too far a leap from there to imagine creating new drugs that counteract the effects of the original mutation.
In such cases, nature itself is the best genetic engineer! This new approach will likely yield many new insights and lead to new approaches for some hard-to-treat diseases.
Professors Norbert Herzog and David Niesel are biomedical scientists at the University of Texas Medical Branch. Learn more at medicaldiscoverynews.com.