TLR7 (toll like receptor 7) is an innate immune system sensor in charge of finding single-stranded RNA and it is therefore one of the ways that our immune systems recognise SARS-CoV-2 as a pathogen.
TLR7, an immune system-related gene, was found to have an uncommon mutation in a genetic investigation of young individuals in their 20s and 30s, with severe instances of COVID-19 (one of which resulted in death) .>R<
Most often a loss in TLR7 function may decrease viral protection and increase severity of viral infections. An overactive TLR7, however, may increase chances of developing lupus.
There are common genetic variants which ca either decrease or increase TLR7 function.
The TLR7 genetics seem to have a severe, inhibitory impact on the production of Interferon type I which can cause much lower antiviral response of the innate immune system and impair its’ key role in fighting off viral infections at the right time.
TLR7 mutations proven to have this effect are most likely the reason why only a small subset of the young and healthy population end up as severe Covid-19 cases. /R/
When researchers examined some of the B cells from young and otherwise healthy males with severe Covid-19, it turned out that these patients’ B cells failed to respond to stimulation of TLR7. This could also potentially help to explain why most of younger patients who end up with severe Covid-19, are male. /R/, /R/