GSTM1 and COVID-19: Therefore, our patient was classified as having “(GSTM1+/+) (GSTT1−/−).” Saadat reported that (GSTM1+/+) (GSTT1−/−) was positively associated with COVID-19 mortality but had no correlation with COVID-19 prevalence; individuals with a lower frequency of the GSTT1-null genotype exhibit higher COVID-19 mortality [2].