C/CTwo copies of the common allele. Published research does not associate this genotype with elevated odds of losing smell or taste during a COVID-19 infection.
C/TOne copy of the variant allele. Published research associates each copy with about 1.11 to 1.12 times higher odds of losing smell or taste during COVID-19, compared with people carrying none. UGT2A1 and UGT2A2 are expressed in the olfactory tissue that lines the nose and are involved in clearing odorant molecules after they are detected.
T/TTwo copies of the variant allele. Published research associates this genotype with the highest odds of COVID-19 related loss of smell or taste among the three, though the effect is modest — this shifts a probability, it does not determine the outcome.
This describes one symptom of one infection and says nothing about how severe a case of COVID-19 would be. Loss of smell that persists after an infection is worth raising with a doctor.
Source: Shelton et al. 2022, Nature Genetics — the UGT2A1/UGT2A2 locus is associated with COVID-19-related loss of smell or taste (PMID 35039640); 33,336 cases and 16,257 controls of European ancestry with Latino replication, odds ratio 1.11-1.12 per T allele.