“People with a genetic mutation that increases the risk of dementia also have a greater chance of having severe Covid-19, researchers have revealed” (The Guardian)

  “The study is the latest to suggest genetics may play a role in why some people are more vulnerable to the coronavirus than others, and could help explain why people with dementia have been hard hit: dementia is one of the most common underlying health conditions among those who have died from Covid-19 in England and Wales.  

“‘It is not just age: this is an example of a specific gene variant causing vulnerability in some people,’ said David Melzer, a professor of epidemiology and public health at Exeter University and a co-author of the study.

“Writing in the Journal of Gerontology: Medical Sciences, Melzer and colleagues report how they analysed data from the UK Biobank, a research endeavour that has collected genetic and health data on 500,000 volunteers aged between 48 and 86.

“The team focused on a gene called ApoE – this gives rise to proteins involved in carrying fats around the body, and can exist in several forms. One such variant, called ‘e4,’ is known to affect cholesterol levels and processes involved in inflammation, as well as increasing the risk of heart disease and dementia.

“The researchers found 9,022 of almost 383,000 Biobank participants of European ancestry studied had two copies of the e4 variant, while more than 223,000 had two copies of a variant called ‘e3.’ The former, the team add, have a risk of dementia up to 14-fold higher than the latter.

“The team then looked at positive tests for Covid-19 between 16 March and 26 April when testing for the coronavirus was largely carried out in hospitals, suggesting the cases were severe.

“The results reveal 37 people who tested positive for Covid-19 had two copies of the e4 variant of ApoE, while 401 had two copies of the e3 variant. After taking into account various factors, including age and sex, the team say people with two e4 variants had more than double the risk of severe Covid-19 than those with two e3 variants.

“Melzer said the findings were not down to people with two e4 variants being more likely to be living in a care home – settings that have been hard hit by Covid-19 – since the association remained even when the team excluded participants with a diagnosis of dementia. None of the Covid-19 positive participants with two e4 variants of the ApoE gene had a dementia diagnosis.

“‘It is pretty bulletproof – whatever associated disease we remove, the association is still there. So it looks as if it is the gene variant that is doing it … This association is not driven by people who actually have dementia,’ said Melzer. The team say further work is needed to unpick the link…” (Research reveals gene role in both dementia and severe Covid-19).