The variation in TLR7 gene prevented it from recognizing SARS-CoV-2 virus (single stranded RNA virus) and could not initiate any immune response, leading to severe infection.
Covid-19 infection :
Covid-19 infection is caused by single stranded RNA virus SARS-CoV-2. It affects the upper respiratory tract (nose, throat and lungs), it causes severe inflammation and even death. The other organs that are affected by the virus are the heart, brain, and kidney. The risk factors of the disease are older age, male gender, and chronic diseases like obesity and diabetes. The infection also occurs in young healthy people without any medical condition.
“A recently published study in the American Journal of Human Genetics, which looked for rare genetic risk factors through an association study in more than half a million people, also revealed TLR7 as the most important factor for severe Covid-19,” said Alexander Hoischen geneticist from Radboudumc Netherlands.
Another study was conducted in Italy among people over 60 years who had a severe covid infection, it revealed that more than 2 percent of the men who were severely affected carried the genetic mutation in TLR7 that had impaired its function. The mutation was not found in the control group.
The researchers are Radboudumc conducted further studies on Spanish and Dutch men and they said that “Hitherto unknown mutations of the TLR7 gene were found in both a Spanish and a Dutch patient. In the Dutch patient again we saw the defective activation of the signaling and impaired production of interferon.”
Individuals with the mutation were vaccinated in order to prevent the severity of the infection when they get exposed to the virus.