Notably, another variant that determines APOE isoforms, rs7412, did not pass the significant threshold, probably because this variant mainly contributes to APOE ε2 isoform while COVID-19 is more associated with APOE ε4 isoform (Kuo et al., 2020; Al-Jaf et al., 2021; Del Ser et al., 2021; Hubacek et al., 2021; Kurki et al., 2021). This evidence concerns the gene APOE and COVID-19.