Signs from the past

Each of us has a biological identity card, with written all the information that determine our characteristics and guide the activities necessary to live. This identity card is our genome, a unique sequence made up of four small units combined in a specific way to form genes.

Over 20 years ago, the first results on human genome sequencing were published, an extraordinary scientific feat that changed the face of medicine. Since then we have information about the regions of the genome that ensure that cells function properly; alterations of this information can cause illness. Sequencing has also highlighted how many parts of our genome are "apparently" useless and has provided hypotheses about our evolution. This large dictionary that we have available continues to be studied, with increasingly precise approaches and increasingly sophisticated methods, continuing to expand our knowledge.

It is also possible to study the genome of our ancestors. This information is important because it traces the path that our genes have taken to adapt and fight difficult environmental situations. An interesting study has highlighted how the "Black Death", one of the largest known pandemics to have affected man, has left indelible "scars" in our genome. Erupted in 1340, during the Middle Ages, the pandemic caused tens of millions of deaths in Europe, Asia and Africa, over a period of seven years. That pandemic caused the death of 30-50% of the population and those who had the right "dictionary" to defend themselves certainly managed to survive.

A study published in the prestigious journal Nature has made it possible to identify the characteristics of this dictionary. The group of researchers from Canada and Chicago examined the DNA of subjects who lived during the plague in two different European regions, the UK and Denmark. By comparing the genomes present before the pandemic and after the pandemic, they identified four genes associated with protection from bubonic plague infection: in the genome "vocabulary" of the survivors, there are sequences capable of protecting the body from invading pathogens. These genetic differences have influenced the evolution of the human genome. Interestingly, this protection from infection has at the same time made us more vulnerable to autoimmune diseases, such as Crohn's disease or rheumatoid arthritis.

Even in biology it is important to discover one's past in order to better understand how one lives in the present. Much information is still hidden in the apparently known genome for over 20 years. What does all this tell us? That it is important to study past history in all its forms, because the questions concerning it can help us to live the present in a more aware and complete way.

Valentina Turinetto
NP November 2022