Fig. 2.
Effect of sex chromosomes on the immune-related functions. The X chromosome contains many immune response-related genes and 10% of all genomic miRNAs that regulate transcription, splicing, and degradation of many genes. It also, through the specification of female identity, directs maternal purging and transmission of mitochondria. Because in the female cells, the inactivation of one of the X chromosomes is random, the female body may contain different alleles of the same gene. For example, different alleles of viral receptor ACE2 may have a different affinity to the virus, which will affect the anti-viral immune response. The Y chromosome regulates many different immune-response functions, immune cell numbers, and immune cell phenotypes through the regulation of transcriptionally inert (heterochromatin) and active (euchromatin) status of X chromosome and autosomes.