We hypothesized that Notch signaling is a mediator of aging-related COVID-19 infection, and its effect may be related to the expression of NOTCH. This hypothesis was investigated with MR of blood eQTLs of NOTCH1-4 from eQTLgen26, against COVID-19-related traits (Fig. 3c and Table 3). The gene discussed is NOTCH1; the disease is COVID-19.