Coronavirus symptoms such as fever, loss of smell are influenced by genetics, study on twins shows
Genes are 50% responsible for the presentation of key symptoms of COVID-19 in people, including fever, fatigue, and loss of taste and smell, according to researchers from King’s College London. This implies that some symptoms of coronavirus have genetic influences. The team, which analyzed data from over 2,600 twins, says the results suggest that some people are more susceptible to coronavirus infection than others because of their genetic makeup.
Infectious diseases may demonstrate a heritable component – that is, the propensity to contract and develop active infection and the severity of the immune response -- is influenced by host genetic factors, say experts. To examine this aspect in the new coronavirus, the researchers analyzed data logged on the COVID-19 symptom tracker app, which has been downloaded by over 2 million people in the UK, including 2,633 twins from ‘TwinsUK.’
The app asks on a daily basis about the presence or absence of common symptoms, including cough, fever, chest pain, delirium, and anosmia (loss of smell and taste).
Adult same-sex twins provided data for analysis between March 25 and April 3. “Understanding how symptoms of COVID-19 pass through the population may indicate the pathogenic mechanisms of SARS-CoV-2 infection (the virus that causes COVID-19) as well as offering utility in the allocation of scarce healthcare resources, particularly intensive care beds,” says the team.
The team used information regarding the twins’ health, symptoms, and level of contact with their co-twin to develop a model to understand how much genes influence symptom presentation in COVID-19. The analysis of data from the tracker app shows that genes were almost 50% responsible for the development of symptoms of delirium, fever, fatigue, shortness of breath, diarrhea, and loss of taste and smell in individuals.
According to the results, the experts found that heritability for fever was 41%, it was 47% for anosmia, 49% for delirium, 32% for fatigue, 34% for diarrhea, and the “predicted COVID-19 gave heritability of 50%.” The environment, on the other hand, was responsible for the development of other symptoms such as hoarse voice, cough, chest pain, and abdominal pain, shows analysis.
“We report that 50% of the variance of ‘predicted COVID-19’ phenotype is due to genetic factors. The current prevalence of ‘predicted COVID-19’ is 2.9% of the population. Symptoms related to immune activation such as fever, delirium, and fatigue have a heritability greater than 35%. The symptom of anosmia, that we previously reported being an important predictive symptom of COVID-19, was also heritable,” says the study, a pre-print version of which has been published.
Heritability estimates including only those twin pairs living apart were largely similar, with fever (41%), anosmia (48%) and shortness of breath (47%), increased for diarrhea (41%), but reduced for delirium (37%) and fatigue (24%), the results indicate.
The genetic basis of this variation in response could provide researchers with important clues for developing treatments for COVID-19 and could help identify high-risk groups of people, say, researchers. “Public health measures to identify those at increased genetic risk of severe infection would be useful as a way of mitigating the economic effects of lockdown and social distancing policies,” says the team.