Recent studies suggest that age-related macular degeneration (AMD) is a clinical risk factor for increased risk for infection and mortality.
AMD has been reported to confer a higher risk of severe complications of COVID-19 infection, including respiratory failure and death (25%), a risk which is higher than Type 2 diabetes (21%) and obesity (13%).
In a study from Boston University, scientists found a novel association between the two diseases.
They hypothesized that AMD and COVID-19 share common genetic risk factors and identified the PDGFB gene.
This gene encodes a platelet-derived growth factor (Pdgf) which has a role in the formation of new blood vessels and is involved in the abnormal blood vessel changes that occur in AMD.
They also found that more severe COVID-19 outcomes were linked to AMD likely arising from genetic predisposition to dysfunction involving complement proteins, as well as with a higher level of Pdgf in blood.
The new findings add to the body of evidence for the increased risk of infection and death from COVID-19 among AMD patients.
The analysis lends credence to previously reported clinical studies that found those with AMD have a higher risk for COVID-19 infection and severe disease, and that this increased risk may have a genetic basis.
In the study, the team did a genome-wide search for variants that are jointly associated with AMD and each of three COVID-19 outcomes (infection rate, critical illness and hospitalization) using large genetic datasets that contained tens of thousands of people.
These datasets were previously assembled and studied separately for genetic factors contributing to the risk of AMD and for each of the COVID-19 disease outcomes.
The researchers then analyzed publicly available data from patients with AMD or COVID-19 and control groups to assess the association of variants in PDGFB with the gene activity.
Finally, they used an analytical technique that allowed them to investigate causal relationships between PDGFB gene variants, Pdgfb concentration in blood, AMD, and COVID-19 outcomes.
These findings suggest that lowering PDGFB gene activity and serum PDGF concentration may reduce the severity of COVID-19, particularly among older people.
The study was conducted by Lindsay A. Farrer et al and published in the Journal of Clinical Medicine.
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