The results indicated that IgM index values were significantly higher in COVID-19 cases tested 7 to 14 days after the onset of symptoms (U=229.5, r=0.33), and more than 14 days (U=43, r=0.36) after the onset of symptoms compared to the patients tested within the first 6 days of the onset of symptoms. The gene discussed is CD40LG; the disease is COVID-19.