Collectively, the above findings demonstrated that alterations of the FTD-COVID-19 and FTD-Breast cancer comorbid genes, AKT3, GFAP, ADCYAP1R1, VDAC1, and C4A, were associated with the pathogenesis of FTD, COVID-19, and Breast cancer. The gene discussed is C4A; the disease is COVID-19.