Genetic factors account for half of the differences observed in COVID-19 symptoms, the Guardian reports.
Researchers from King's College London asked volunteers from the TwinsUK project to track their symptoms using the C-19 Covid Symptom Tracker app, which the Guardian notes has also been released to the public to track their own health. As King's College's Tim Spector and his colleagues report in a yet-to-be peer reviewed preprint posted to MedRxiv, some COVID-19 symptoms appear heritable.
In all, their sample included 728 pairs of twins, including 537 monozygotic and 191 dizygotic twin pairs. Symptom prevalence among their cohort, the researchers say, was similar to the population at large. By comparing symptoms in the different groups of twins, the researchers found about half the variance in the predicted COVID-19 phenotype is due to genetic factors. In particular, they found symptoms like fever, delirium, and fatigue have a heritability that is greater than 35 percent and anosmia has a heritability of 48 percent.
"This disease is very weird, the way it has a very different presentation in the population in different people — what we are showing is that isn't random," Spector tells the Guardian. "It is not mainly due to where you live or who you have seen; a lot of it is something innate about you.