rs200553089, also known as c.2383G>T or p.Val795Phe (V795F), is an extremely rare variant located in the TLR7 gene on the X chromosome.
The rs200553089(T) variant was reported based on exome sequencing of two brothers of African descent, ages 21 and 23, who both required intubation and mechanical ventilation due to COVID-19-related respiratory failure. The clinical severity of COVID-19 in these two young men, plus in vitro and in silico experiments, led the researchers to the hypothesis that this mutation creates a defective TLR7 protein and therefore impaired immune response to the SARS-CoV-2 virus.[PMID 32706371
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Another TLR7 mutation, c.2129_2132delAACT, was identified by these researchers in a second family severely affected by COVID-19 (this mutation currently lacks an rs# in dbSNP). Both the c.2129_2132delAACT and c.2383G>T mutations are apparently extremely rare, since neither was ever observed in the sequences from ~90,000 people represented in the gnomAD database.
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