Two brothers in the Netherlands fell sick with Covid-19 in the early days of the coronaviruses. They were young and healthy at the time. The brothers were admitted to the intensive care unit at the end of March. The older brother couldn’t breathe on his own and needed help. His younger brother died from the effects of the disease after coming down with a high temperature.
If you look at all the men hospitalized from Covid-19, it’s very unlikely that that happens to such young individuals, and then it happened twice in the same family. That was amazing to us. Alexander Hoischen, PhD, a geneticist at the Radboud University Medical Center in Nijmegen, was contacted by a physician to investigate why the brothers were so affected. It could have been a coincidence, but Hoischen thought it was possible that the brothers had a genetic trait that affected their immune systems.
Over the course of the Pandemic, it has become clear that certain factors, such as being elderly, male, obese, or a racial or ethnic minority, raise a person’s risk of developing severe Covid-19 and dying from it. The likelihood of death increases when there is an underlying chronic condition like diabetes, heart disease, or high blood pressure. Many cases of Covid-19 can be explained by these factors.
Two more brothers landed in Dutch hospitals. Two young men were put on ventilators after they had difficulty breathing. The younger brother had died from the disease. The brothers were discharged from the hospital after a week. Hoischen was more convinced that there was a genetic component to the young men’s severe disease when he learned of the second pair of brothers.
A person’s genetics could be a factor. Scientists all over the world have been analyzing huge genetic datasets, collecting DNA samples from Covid-19 patients, and analyzing their genomes in hopes of finding genetic signatures that explain why some people develop very serious symptoms. There are a wide range of symptoms associated with the coronaviruses. Some people get a mild cough while others go into respiratory failure. Many feel better in a few days, while others are not. Why does a healthy person in his 20s end up with a disease that affects most people his age?
The results of these studies could help researchers develop new treatments. They could also lead to genetic tests that can predict someone’s Covid-19 risk. The distribution of vaccine could be influenced by genetic traits that lead to more serious symptoms. When a vaccine becomes available, people with these characteristics could be prioritized. The Covid Human Genetic Effort and the Covid-19 Host Genetics Initiative are international consortiums that are pooling together data from thousands of patients in dozens of countries. Consumer genetics companies 23andMe and Ancestry are looking for genetic links from millions of customers.
The degree to which the impact is seen is yet to be determined. Catherine Ball, PhD, chief scientific officer at Ancestry, says that it is not uncommon for people to have genetic differences that make them more or less susceptible to infections.
There is a specific genetic trait that has an effect on immunity. The genetic change protects against HIV by blocking the virus from entering immune cells. Only a small percentage of northern Europeans carry two copies of the same genetic abnormality.
The most common genetic trait associated with immunity is the sickle cell trait, which is most common in people of African descent. People with one of the two normal genes for sickle cell disease are protected from Malaria. People who inherit two copies of the same genes from their parents can develop a chronic and painful blood condition.
There will be a genetic component associated with disease severity, according to Joseph Petrosino, PhD, chair of the department of infectious diseases at the Baylor College of Medicine. The degree to which the impact is seen is yet to be determined.
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