The X chromosome with over 1000 genes holds some immune-related genes with relevance to COVID-19, such as the angiotensin-converting enzyme 2 (ACE2) virus receptor gene, toll-like receptor 7 (TLR7), and the androgen receptor gene (AR), which are known to appear differently in men and women through hormonal influence, genetic and epigenetic factors [15, 17, 20, 23, , –26]. Here, ACE2 is linked to COVID-19.