Specific parts of the immune response that have been suggested to play a role in COVID-19 include the pattern recognition receptor TLR7, which is X-linked and more expressed in females [24], the protein ACE2 which has been described as the entry pathway of the SARS-CoV-2 [25] and differences in antibody responses which could lead to immune-mediated pathology in men [26]. Here, ACE2 is linked to COVID-19.