Long-COVID olfactory dysfunction: allele E4 of apolipoprotein E as a possible protective factor

Area of Science:

• Neurology
• Infectious Diseases
• Genetics

Background:

• Olfactory dysfunction (OD) is a common COVID-19 symptom.
• Apolipoprotein E (APOE) influences viral entry and COVID-19 severity.
• No prior studies linked COVID-19 severity, OD, and APOE polymorphisms.

Purpose of the Study:

• To investigate the epidemiology of OD.
• To examine the relationship between OD and APOE polymorphisms in Long-COVID patients.

Main Methods:

• Prospective cohort study in a post-COVID neurological clinic.
• Defined OD and persistent OD (>3 months post-infection).
• Collected blood samples for APOE genotyping in 186 patients.

Main Results:

• Persistent OD patients were younger with lower hospitalization rates.
• APOE E4 allele frequency was lower in the persistent OD group (p=0.035).
• Contradicts literature associating E4 with worse outcomes.

Conclusions:

• Suggests APOE E4 may be a protective factor against persistent OD.
• Provides novel insights into the correlation between APOE and COVID-19-related olfactory dysfunction.