Viral infections are less frequent but more severe in people with Down syndrome due to oscillating immune response

Individuals with Down syndrome have less-frequent viral infections, but when present, these infections lead to more severe disease. New findings publishing on October 14 in the journal Immunity show that this is caused by increased expression of an antiviral cytokine type I interferon (IFN-I), which is partially coded for by chromosome 21. Elevated IFN-I levels lead to hyperactivity of the immune response initially, but the body overcorrects for this to reduce inflammation, leading to increased vulnerability later in the viral attack. “Usually too much inflammation means autoimmune disease, and immune suppression usually means susceptibility to infections,” says senior study author Dusan Bogunovic of the Icahn School of Medicine at Mount Sinai. “What is unusual is that individuals with Down syndrome are both inflamed and immunosuppressed, a paradox of sorts. Here, we discovered how this is possible.” Down syndrome is typically caused by triplication of chromosome 21. This syndrome affects multiple organ systems,...