Context: Recently, a large scale study from the UK has found that a faulty gene associated with dementia may double the risk of developing severe Covid-19 infection.
Background 

• The gene is called APOE, and exists in different forms, one of which is termed e4e4. Researchers analysed data from the UK Biobank, which collects health and genetic data on 500,000 people.

Key Points

• Researchers found high risk of severe Covid-19 infection among European ancestry participants who carry two faulty copies of this gene. 
• One in 36 people of European ancestry have two faulty copies of this gene, and this is known to increase risks of Alzheimer’s disease up to 14-fold and also increases risks of heart disease. 
• The team found that carrying these gene mutations doubles the risks of Covid-19, even in people who had not developed these diseases. The same team has previously found that people with dementia are three times more likely to get severe Covid-19. 
• It said part of the increased risk may have been due to exposure to the high prevalence of the virus in care homes. However, the new study suggests that a genetic component may also be at play. 
• The team found that people with the APOE e4e4 genotype were at double the risk of developing severe Covid-19, compared to those with the common e3e3 form of the APOE gene. 
• In this analysis, 2.36% (9,022) of 3.82 lakh participants with European ancestries had the APOE e4e4 faulty gene, but 5.13% (37) of 721 who tested positive for Covid-19 had this gene variant, suggesting the risk is doubled compared to e3e3. 
• Researchers might now be able to pinpoint how this faulty gene causes vulnerability to COVID-19. This could lead to new ideas for treatments.