The frequencies of the FAS rs1800682 (A/G), FAS rs2234767 (G/A), and FASL rs5030772 (A/G) polymorphisms were not associated with the severity of COVID-19, unlike the findings of studies on other viral infections, where the high frequency of the FAS rs1800682 (A/G) polymorphism was associated with a high proviral load in individuals with HTLV-1 who had HTLV-1-associated myelopathy (HAM), and the FAS rs1800682 (A/G) polymorphism was considered a possible risk factor for progression to HAM [36,37]. This evidence concerns the gene FAS and tropical spastic paraparesis.