Deficient DNA mismatch repair and persistence of SARS-CoV-2 RNA shedding: a case report of hereditary nonpolyposis colorectal cancer with COVID-19 infection

BACKGROUND: Several independent risk factors have been reported to influence viral shedding following COVID-19 infection, but the influence of host-related molecular factors has not yet been described. We report a case of a cancer patient with Lynch syndrome (hereditary nonpolyposis colorectal cancer, HNPCC) who manifested SARS-CoV-2 PCR (polymerase chain reaction) positivity for at least 54 days after contracting mild COVID-19 illness. We propose that deficient mismatch repair (MMR) may play a role in the prolonged SARS-CoV-2 RNA shedding. CASE PRESENTATION: A patient with Lynch syndrome was under surveillance for metastatic adenocarcinoma after completing palliative chemotherapy in October 2019. Between the period of April 2020 to June 2020, he was admitted multiple times to address several clinical needs mainly related to his underlying malignancy. These included progressive disease observed in the aortocaval lymph nodes leading to recurrent episodes of upper gastrointestinal bleeding, dehydration resulting in acute kidney injury and a short-lived episode of pyrexia. A SARS-CoV-2 PCR of the nasopharyngeal swab (NPS) was positive at his initial admission with mild COVID-19 symptoms. He remained positive on subsequent admissions when tested routinely for SARS-CoV-2 without demonstrating any apparent clinical features of COVID-19 infection. The MMR pathway, a component of DNA damage response (DDR), is impaired in Lynch syndrome due to an inherited genetic mutation. This pathway is also required for viral clearance from the host cells following certain RNA viral infections like influenza virus and other coronaviridae. Here we provide a current understanding of the importance of DDR deficiencies in the clearance of RNA virus and suggest how this may play a similar role in the clearance of COVID-19, as evident in our case that demonstrated persistent positivity. CONCLUSION: The importance of understanding the scientific basis of extended viral shedding during the COVID-19 pandemic is now centre-stage in the establishment of robust track and trace services to allow the recovery and function of societies and economies. This patient with Lynch syndrome recovered from infection but had prolonged viral positivity, which might merit further investigation to better understand the effect of this condition on infection duration and outcome.