other <div style="text-align: justify;"><span style="font-family:Times New Roman;"><span style="font-size:14px;"><strong><span style="color:#0e101a">Introduction:</span></strong><span style="color:#0e101a"> ARS-CoV-2 infection (COVID-19) is a major pandemic that has caused significant mortality and morbidity worldwide. About 80% of patients had mild or moderate disease, and 5% of patients with severe disease developed severe disease. Long COVID-19, also known as post-COVID-19 syndrome, is a condition in which individuals continue to experience symptoms for weeks or months after recovering from COVID-19. There is a lack of sufficient data on the risk factors for post-COVID-19 sequelae in children. This study aimed to evaluate the long-term effects of severe COVID-19 on promotor methylation and expression genes, including <i>CCR5</i>, <i>CCR6</i>, <i>CCR9</i>, and <i>CCL3</i> in children. </span><br> <b><span style="color:#0e101a">Methods and Materials:</span></b><span style="color:#0e101a"> Clinical data and blood samples from 94 long COVID patients and 25 healthy subjects were collected. Promotor methylation and mRNA expression of <i>CCR5</i>, <i>CCR6</i>, CCR9, and <i>CCL3</i> genes in these patients and control group were assessed through methylation-specific PCR and real-time PCR assay. </span><br> <b><span style="color:#0e101a">Results:</span></b><span style="color:#0e101a"> Our result indicated that promotors of CCR5 (<i>p</i> = 0.01) and CCL3 (<i>p</i> = 0.006) in convalescence COVID-19 children were hyper-methylated compared to the healthy control group. Subsequently, <i>CCR5</i> and <i>CCL3</i> transcripts decreased compared to the control group (<i>p</i> = 0.01). In addition, <i>CCL3</i> transcript in children with convalescent COVID-19 decreased compared to the control group (<i>p</i> = 0.008). However, we did not observe any significant modification in the transcript levels of <i>CCR6</i> (<i>p</i> = 0.7) and <i>CCR9</i> (<i>p</i> = 0.46) in children with convalescent COVID-19 compared to all the control groups. </span><br> <b><span style="line-height:115%"><span style="color:#0e101a">Conclusion and Discussion:</span></span></b><span style="line-height:115%"><span style="color:#0e101a"> The <i>CCR5</i> and <i>CCL3</i> promoter region DNA methylation and the subsequent decrease in the expression of these genes were possibly correlated with long-term COVID-19 occurrence in children. Our study revealed additional data on the SARS-CoV-2-mediated inflammatory response.</span></span><br> <br> <img alt="" src="./files/site1/images/888.jpg" style="width: 1000px; height: 36px;" ></span></span></div> CCR5 receptor antagonists, Chemokine CCL3, Methylation 332 332 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-4696-352&slc_lang=other&sid=1 Hamidreza Farhadirad No Nasir Arefinia Yes Zohreh-Al-Sadat Ghoreshi No Fateme Sadeghzade No