Men are at increased risk of severe COVID-19, in part because of Y chromosome loss

Men are at higher risk of severe COVID-19 compared to women
.
Researchers at Uppsala University have now shown that this may be due to the loss
of the Y chromosome in some white blood cells.
These findings could eventually be used to assess the risk of severe COVID-19 and potentially improve treatment
.

A common genetic change in men is the loss
of the Y chromosome (LOY) in some white blood cells.
Interestingly, this change is more common
with age.

During the COVID-19 pandemic, it was quickly discovered that men were more severely affected by the disease
.
Up to 75% of patients in intensive care units are men, and the proportion of deaths in men is also higher than that of women
.
In the current study, the researchers found a link between
LOY and the risk of severe COVID-19.

"We looked at blood samples
taken from more than 200 male patients in intensive care units between early 2020 and summer 2021.
Bozena Bruhn-Olszewska, a researcher at Uppsala University, said: "According to the World Health Organization's classification, LOY is associated with
both disease severity and risk of death.
"

Some of the findings in the study support the importance
of LOY for the development of severe COVID-19.
A higher proportion of LOY may be associated with impaired lung function, such as hypooxygenation
.
Complications in the form of thrombosis are also associated with
a higher percentage of LOY in specific types of white blood cells.
In addition, a high percentage of
LOY cells was noted to be temporary.

"We had the opportunity to analyze samples taken three to six months after some patients were discharged from the intensive care unit
.
In these samples, the proportion of LOY cells drops
dramatically.
To our knowledge, this is the first time that LOY has been shown to have dynamic properties associated with acute infectious diseases," explains
Hannah Davis, a researcher at Uppsala University.

The researchers believe that LOY could be used as a biomarker to predict which patients are at risk
of developing severe disease due to COVID-19.

"Our findings contribute to a better understanding of the importance of LOY for disease susceptibility, particularly in relation
to immune system function.
" We also think that this new knowledge may be related to other common viral infections that are more severe in men than women," said Jan Dumanski, a professor at Uppsala University who led the study
.

The study was carried out
in collaboration with researchers from the Sahlgrenska Academy in Gothenburg, the National Bioinformatics Infrastructure of Stockholm University and the Medical University of Gdansk in Poland.