Written By: Longjam Dineshwori | Updated : February 9, 2021 8:19 PM IST
Researchers recommend early vaccination for people with Down syndrome.
Anybody can get COVID-19, but certain groups of people are more vulnerable to the infection and have higher risk of dying from it. Earlier studies have revealed that COVID-19 is ten times deadlier for people with Down syndrome, raising calls for priority vaccination of this medically vulnerable group.
Now, a new study has identified the genetic factors that make people with Down syndrome susceptible to the SARS-CoV-2 infection and disease progression, further strengthening the call for their early vaccination.
Researchers have found higher expression levels for two genes in people with Down syndrome that supposedly make them more vulnerable to severe COVID-19.
One of these is TMPRSS2, a gene that codes for an enzyme that facilitates entry of SARS-CoV-2 in human cells. It is located on chromosome 21 and people with Down syndrome have three copies of chromosome 21 rather than the usual two. According to the study, TMPRSS2 had 60% higher levels of expression in Down syndrome.
The researchers also found extra copies of CXCL10, a gene that can trigger out-of-control inflammation resulting in the body's immune system attacking its own lung cells. Known as a cytokine storm, this phenomenon is one of the main causes of hospitalization and death among Covid-19 patients. This could also make individuals with Down syndrome more susceptible to late onset complication such as lung fibrosis, the researchers stated in their study report published in the journal Scientific Reports.
Additionally, the new study found lower expression of the NLRP3 gene, which is critical for the maintenance of homeostasis against pathogenic infections, in Down syndrome patients. The researchers hypothesize this may make people with Down syndrome more susceptible to subsequent bacterial infections post COVID-19.
However, they also found two genes linked to an interferon response IFNAR1 and IFNAR2 on chromosome 21. This indicates that people with Down syndrome may have an overactivated interferon response, an important innate defense that shuts down viral replication within cells.
A large U.K. study published in the Annals of Internal Medicine in October reported that people with Down syndrome affected by COVID-19 are five times more likely to be hospitalized and 10 times more likely to die than the general population.
The authors cited a combination of background immune abnormalities and extra copies of key genes in people with DS as possible reasons for their vulnerability to severe COVID-19.
A recent survey from the international Trisomy 21 Research Society found a higher risk of COVID-19 mortality for people with Down syndrome above the age of 40 a mortality risk of 51% versus 7% for those under 40.
Apart from the genetic factors, experts say that the typical anatomy of people with Down syndrome, including large tongues, small jaws, and relatively large tonsils and adenoids, and lax throat muscle tone, may put them at higher risk of respiratory infections.
Because of these reasons, researchers have recommended prioritizing people with Down syndrome for speedy vaccination against COVID-19 worldwide.
Down syndrome, also known as trisomy 21, is a genetic disorder characterised by delay in growth, mild to moderate intellectual disability, and characteristic facial features.
Disclaimer: The content on TheHealthSite.com is only for informational purposes. It is not at all professional medical advice. Always consult your doctor or a healthcare specialist for any questions regarding your health or a medical condition.
