COVID-19 and Individual Genetic Susceptibility/Receptivity: Role of ACE1/ACE2 Genes, Immunity, Inflammation and Coagulation. Might the Double X-chromosome in Females Be Protective against SARS-CoV-2 Compared to the Single X-Chromosome in Males?
Level 5 - mechanism / opinion, no new human data
Narrative review and mechanistic reasoning without original empirical data
PubMed 32423094 · doi:10.3390/ijms21103474
What was done
This narrative review synthesized early COVID-19 epidemiological data regarding sex disparities in infection severity and mortality. The authors evaluated potential biological mechanisms underlying these differences, focusing on the genetic localization and regulation of the *ACE2* gene, immune response genes on the X-chromosome, and related pathways in inflammation and coagulation.
What was found
The authors cited early surveillance figures indicating higher male susceptibility and mortality: males were reported to be 65% more likely to die from COVID-19 than females; WHO and Chinese datasets showed ~1.7% mortality in infected females compared to 2.8% in males; and Hong Kong hospital data showed 32% of male versus 15% of female patients required intensive care or died. The authors hypothesized that because the *ACE2* gene and key immune-related genes reside on the X-chromosome, females benefit from potential heterozygosity and cellular mosaicism, potentially aiding ACE1/ACE2 rebalancing and mitigating severe inflammation and thrombosis.
Why it matters
The paper presents a mechanistic hypothesis linking sex chromosome genetics—specifically female X-heterozygosity and *ACE2* regulation—to observed sex-based differences in severe COVID-19 outcomes.
Limits
This is a narrative review and hypothesis paper providing no original experimental or patient-level data. The cited epidemiological statistics represent preliminary, unadjusted surveillance summaries that did not control for confounding variables such as age, comorbidities, or exposure patterns.
Cited by
- context The ACE2 gene is located on the X chromosome, giving women two copies and higher expression levels than men.