Synonymous variant of TLR7 at restriction site rs864058 identified in Covid 19 Pakistani patients

TLR7, the receptor accountable for immune response to RNA viruses, has been studied extensively to identify its variants related to the severity of Covid-19 in different populations worldwide. However, the genotype of Pakistani population is still unknown. This study aimed to determine the TLR7 genotypes and their relation with severity in our population.

This cross sectional study collected data on 151 Covid-19 positive patients (aged 18-80 years), from June 2022 to May 2023, after an informed consent, from Ziauddin University and Hospital. Prior to that approval from ethics review committee was taken. The demographic variables and comorbidities were recorded along with health status till LAMA (Leave Against Medical Advise), recovery or death. The DNA was extracted from collected blood samples, PCR and Sanger sequencing was done for identification of TLR7 variants. SPSS was used for data analyses and Chi-Square for categorical variables. P-values of <0.05 was considered significant.

Out of 151 patients' sequencing was done for 59 samples. The restriction site, rs864058 of TLR7 gene, identified G/A and G/G variants. This missense variant of TLR7 identified at rs864058 of TLR7 gene, has not been previously reported in population control databases. The genotype G/G was main variant of 49 (83%) patients, whereas, G/A was found in 10 (17%). Majority, 25 (51%) of patients with mild covid-19 had GG genotype but results were not significant (P=0.684). Among female patients the main genotype was GA 8 (80%) while male had G/G 29 (59.2%) with significant results (P=0.024). Since G/G genotype was the major genotype, high percentage was found in hypertensives [20 (40.8%)], Diabetics [13 (26.5%)], depression [24 (49%)] and pneumonia patients [20 (40.8%)]. However, significant association (P=0.023) was only found with pneumonia. Males, in majority had severe [17 (68%)] infection and death [40 (26.4%)], whereas, females had mild [14 (25%)] with [12 (7.9%)] deaths.

A variant rs864058 "G/A" of TLR7, in relation to covid-19 were found in our population. Males were found more at risk of morbidity and mortality due to covid-19. Larger studies are required to further confirm these results.