A faulty gene linked to dementia doubles the risk of developing coronavirus, a new study has suggested.
Researchers linked the fault, found in people of European ancestry, to a greater risk of the virus even when they had not developed dementia.
The finding that people may be genetically predisposed to suffer from Covid-19 heralds the prospect of one day developing a genetic treatment that helps patients to overcome the infection.
It could also be a means of more accurately identifying very high-risk people who need to be shielded from the threat of the disease.
One in 36 people of European ancestry have two faulty copies of the ApoE e4e4 gene, which is known to increase the risk of dementia 14-fold.
Scientists at the universities of Exeter and Connecticut analysed data from 382,188 people.
They found that, overall, 2.36pc of people had the faulty gene, but that of those who had tested positive for Covid-19, 5.13pc possessed it.
It is known that dementia is one of the key underlying risk factors for death from the virus, with sufferers facing a three-fold risk of developing severe symptoms.
Until now, however, many experts had assumed that much additional risk was explained by the fact people with dementia were more likely to be vulnerable to Covid-19 due to living in care homes, or because of their age or other infirmities that come with the condition.
Dr Chia-Ling Kuo, who co-authored the study at the University of Connecticut, said: "This is an exciting result because we might now be able to pinpoint how this faulty gene causes vulnerability to Covid-19.
"This could lead to new ideas for treatments."
Prof David Melzer, who led the team at Exeter, said: "Several studies have now shown that people with dementia are at high risk of developing severe Covid-19.
"This study suggests that this high risk may not simply be due to the effects of dementia, advancing age or frailty, or exposure to the virus in care homes.
"The effect could be partly due to this underlying genetic change, which puts them at risk for both Covid-19 and dementia." (© Daily Telegraph, London)