Investigators are trying to determine why some people remain asymptomatic after catching the SARS-2 virus while others become deathly ill. Could dementia genes make a difference?
The e4 variant of the APOE gene is linked to a higher risk of Alzheimer’s disease. All of us have some form of apolipoprotein E, termed APOE for short. It comes in several varieties, including e2 (which reduces risk of Alzheimer disease), e3 which is the most common form and e4 (which increases risk for Alzheimer disease, especially for people with two copies of e4) (Nature Reviews. Neurology, Feb. 2013). Because genes come in pairs, everyone has two copies, but they don’t have to match.
Dementia Genes and COVID-19:
British scientists have just reported that people with two copies of the e4 gene variant may also be at greater risk for COVID-19 (Journal of Gerontology: Medical Sciences, May 26, 2020). To determine this, they used genetic data on more than 450,000 people of European ancestry in the UK Biobank. Roughly 9,000 of these Britons carried two copies of the e4 type of APOE. That amounts to approximately 2 percent. Alarmingly, however, among those who had tested positive for COVID-19, more than 5 percent had two copies of the e4 variant. As a result, the researchers concluded that people with two e4 APOE genes were about twice as likely to have become infected as those with the more common e3 variants.
The lead investigator noted that people with dementia are at especially high risk of developing severe COVID-19. While some of that could be explained by the virus spreading through long-term care facilities, the connection with the double e4 gene variant may also play a role.
Other researchers urge caution, however. Although the percentage of those with COVID-19 is high, the actual total number is very small. Only 37 people fell into this category. Consequently, more research is needed to confirm this link.