It seems that the genetic risk of an APOE4 variant in the APOE gene would not only increase risk for Alzheimer’s but also would increase the chances of getting infected by the COVID-19 virus.
The APO protein is involved in cholesterol metabolism and the immune system. However, its precise role in Alzheimer’s disease is as yet unknown.
Having 2 copies of the APOE4 variant instead of the more common APOE3 variant implies an increased risk of suffering from Alzheimer’s. A new study 1 on more than 600 people in England that were positively tested for COVID-19 shows that these variants can lead to almost a two-fold increase in the likelihood of getting infected with the coronavirus.
The study used data from the UK Biobank, a health data resource where the genetic and health information from about 400.000 people are made available for research. Among those only 4% have a double copy of the APOE4 variant while the double APOE3 positive appears in 69% of the population. The rest have one copy of each version.
Yet, for such a low appearance in the general population, the researchers found that APOE4 was the version most commonly found in people with a COVID-19 positive diagnosis: 37 out of 622 people had the double APOE4 gene variant, which translated to a 100.000 people would mean that about 410 people with APOE4 in double copy will test positive for COVID-19, whereas for those carrying the APOE3 variant, it would be only about 179 people. Quite a difference in numbers, isn’t it?
Even though the numbers point to APOE4 being a risk factor for COVID-19 infection, the researchers do not have an answer as to why that can be. However, I wonder if it being a protein related with cholesterol metabolism, which in turn is a fundamental component of biological membranes, won’t have something to do with it…
- Chia-Ling Kuo, PhD, Luke C Pilling, PhD, Janice L Atkins, PhD, Jane A H Masoli, MBChB, João Delgado, PhD, George A Kuchel, MD, David Melzer, MBBCh, PhD (2020) APOE e4 Genotype Predicts Severe COVID-19 in the UK Biobank Community Cohort, The Journals of Gerontology: Series A, , glaa131, doi: 10.1093/gerona/glaa131 ↩