Abstract
Introduction Albeit the pathogenesis of COVID-19 remains unclear, host’s genetic polymorphisms in genes infection and reinfection, inflammation, or immune stimulation could play a role in determining the course and outcome. Methods We studied in the early phase of pandemic consecutive patients (N=383) with SARS-CoV-2 infection, whose subsequent clinical course was classified as mild or severe, the latter being characterised by admission to intensive therapy unit or death. Five host gene polymorphisms (MERTK rs4374383, PNPLA3 rs738409, TLL-1 rs17047200, IFNL3 rs1297860, and INFL4 rs368234815) were assessed by using whole nucleic acids extracted from nasopharyngeal swabs. Specific protease cleavage sites of TLL-1 on the SARS-CoV-2 Spyke protein were predicted in silico. Results Male subjects and older patients were significantly at higher risk for a severe outcome (p=0.02 and p<0.001, respectively). By considering patients ≤ 65 years, after adjusting for potential confounding due to sex, an increased risk of severe outcome was found in subjects with the GG genotype of PNPLA3 (adj-OR: 4.69; 95% CI= 1.01-22.04) or TT genotype of TLL-1 (adj-OR=9.1; 95% CI= 1.45-57.3). In silico evaluation showed that TLL-1 is potentially involved in the Spike protein cleavage.Discussion Subjects carrying a GG genotype in PNPLA3 gene might have a constitutive upregulation of the NLRP3 inflammosome and be more prone to tissue damage when infected by SARS-CoV-2. The TT genotype in TLL-1 gene might affect its protease activity on the SARS-CoV-2 Spyke protein, enhancing the ability to infect or re-infect host’s cells. The untoward effect of these variants on disease course is evident in younger patients due to the relative absence of comorbidities as determinants of prognosis.