# DNA Salivary Methylation Levels of the ACE2 Promoter Are Not Related to ACE2 (rs2285666 and rs2074192), TMPRSS2 (rs12329760 and rs2070788) and ACE1 rs1799752 Polymorphisms in COVID-19 Survivors with Post-COVID-19 Condition

## TL;DR

This study found no link between genetic variations and DNA methylation in the ACE2 promoter among hospitalized COVID-19 survivors with lingering symptoms.

## Contribution

The study is the first to investigate the relationship between specific genetic polymorphisms and ACE2 promoter methylation in post-COVID-19 condition.

## Key findings

- No significant differences in ACE2 promoter methylation were found based on genetic polymorphisms.
- 88.1% of participants reported at least one post-COVID symptom.
- The study cohort included individuals hospitalized during the first pandemic wave.

## Abstract

Genetics and epigenetics are mechanisms proposed for explaining post-COVID-19 condition. This secondary analysis aimed to investigate if DNA methylation levels of the ACE2 promoter are different depending on the genotype of five COVID-19-related polymorphisms in individuals who had been previously hospitalized due to SARS-CoV-2 infection. We collected non-stimulated saliva samples from 279 (48.7% female, age: 56.0 ± 12.5 years) previously hospitalized COVID-19 survivors. The participants self-reported for the presence of post-COVID symptomatology that started after the infection and persisted at the time of the appointment. Three potential genotypes of ACE2 rs2285666 and rs2074192, TMPRSS2 rs12329760 and rs2070788, and ACE1 rs1799752 polymorphisms were identified from saliva samples. Further, methylation levels at five different locations (CpG) of dinucleotides in the ACE2 promoter were quantified using bisulfited pyrosequencing. Differences in the methylation percentage (%) of each CpG according to the genotype of the five polymorphisms were analyzed. Participants were evaluated up to 17.8 (SD: 5.2) months after hospital discharge. Eighty-eight percent (88.1%) of patients reported at least one post-COVID symptom (mean number of post-COVID symptoms: 3.0; SD: 1.9). Overall, we did not observe significant differences in the methylation levels of the ACE2 promoter according to the genotype of ACE2 rs2285666 and rs2074192, TMPRSS2 rs12329760 and rs2070788, or ACE1 rs1799752 single nucleoid polymorphisms. This study did not find an association between genetics (genotypes of five COVID-19-associated polymorphisms) and epigenetics (methylation levels of the ACE2 promoter) in a cohort of COVID-19 survivors with post-COVID-19 condition who were hospitalized during the first wave of the pandemic.