Background: Inconclusive SARS-CoV-2 real-time reverse transcription-PCR (rRT-PCR) test results, which are positive for one or more target genes but not all, are problematic in clinical laboratories. In this study, we aimed to investigate the cause and clinical relevance of such inconclusive results. Methods: rRT-PCR was performed using the Allplex 2019-nCoV assay kit (Seegene Inc., Korea) targeting the following three genes: E, RdRp, and N. For all inconclusive test results reported from March to June 2020, the frequency per kit, lot number, specimen type, cycle threshold (Ct) and peak values of the amplification curves, positive target genes, and results of repeated or consecutive tests were analyzed. Results: A total of 43,268 tests were conducted, of which 93 (0.21%) were inconclusive—49 from 11 coronavirus disease 2019 (COVID-19) patients and 44 from non-COVID-19 patients.In COVID-19 patients, the results were inconclusive 11.9 ± 4.7 days after diagnosis and were negative 8.8 ± 5.5 days after the inconclusive results were reported. However, in nonCOVID-19 patients, they were all negative upon retest and 81.8% of them were identified to have yielded in 2 out of 8 lots. The most frequently positive target genes were N (55.4%) in COVID-19 and RdRp (61.2%) in non-COVID-19 patients, respectively. No difference was observed in the Ct or peak values of the amplification curves for inconclusive samples between COVID-19 and non-COVID-19 cases. Conclusion Inconclusive test results should be reported neither positive nor negative. Such results can be reported as inconclusive without retesting in COVID-19 patients; however, they should certainly be confirmed by a retest in non-COVID-19 patients or newly diagnosed cases.

Hu5F9-G4, an immunoglobulin 4 (IgG4) monoclonal humanized antibody targeting CD47, is under active clinical trials as a novel immunotherapeutic for hematologic and solid malignancies and can cause pretransfusion testing interference. In this study, we demonstrate our first experience of Hu5F9-G4 interference with serologic testing and mitigate this interference through multiple platelet alloadsorption. A 69-year-old woman with a history of ureter cancer presented with anemia. On routine blood group typing, the patient showed strong agglutination (4+) with anti-A, A, and B cells. Unexpectedly, antibody screening and identification showed panreactivity to all panel cells, although the autocontrol result was negative. Medical records revealed that she was enrolled in an anti-CD47 clinical trial. To eliminate interference by the drug, we attempted alloadsorption using pooled platelets that were prepared from segments of random single donor platelets. After seven alloadsorption sessions using pooled allogeneic platelets, the ABO discrepancy and panreactivity was resolved. To our knowledge, this is the first demonstration of anti-CD47 interference elimination in Korea.

Hu5F9-G4, an immunoglobulin 4 (IgG4) monoclonal humanized antibody targeting CD47, is under active clinical trials as a novel immunotherapeutic for hematologic and solid malignancies and can cause pretransfusion testing interference. In this study, we demonstrate our first experience of Hu5F9-G4 interference with serologic testing and mitigate this interference through multiple platelet alloadsorption. A 69-year-old woman with a history of ureter cancer presented with anemia. On routine blood group typing, the patient showed strong agglutination (4+) with anti-A, A, and B cells. Unexpectedly, antibody screening and identification showed panreactivity to all panel cells, although the autocontrol result was negative. Medical records revealed that she was enrolled in an anti-CD47 clinical trial. To eliminate interference by the drug, we attempted alloadsorption using pooled platelets that were prepared from segments of random single donor platelets. After seven alloadsorption sessions using pooled allogeneic platelets, the ABO discrepancy and panreactivity was resolved. To our knowledge, this is the first demonstration of anti-CD47 interference elimination in Korea.

Maternally inherited diabetes and deafness (MIDD) is a rare mitochondrial disorder primarily resulting from m.3243A>G mutation. The clinical characteristics of MIDD exhibit significant heterogeneity. Our study aims to delineate these characteristics and determine the potential correlation with m.3243A>G heteroplasmy levels. This retrospective, descriptive study encompassed patients with confirmed m.3243A>G mutation and diabetes mellitus at Seoul National University Hospital. Our cohort comprises 40 patients with MIDD, with a mean age at study enrollment of 33.3±12.9 years and an average % of heteroplasmy of 30.0%± 14.6% in the peripheral blood. The most prevalent comorbidity was hearing loss (90%), followed by albuminuria (61%), seizure (38%), and stroke (33%). We observed a significant negative correlation between % of heteroplasmy and age at diabetes diagnosis. These clinical features can aid in the suspicion of MIDD and further consideration of genetic testing for m.3243A>G mutation.

Maternally inherited diabetes and deafness (MIDD) is a rare mitochondrial disorder primarily resulting from m.3243A>G mutation. The clinical characteristics of MIDD exhibit significant heterogeneity. Our study aims to delineate these characteristics and determine the potential correlation with m.3243A>G heteroplasmy levels. This retrospective, descriptive study encompassed patients with confirmed m.3243A>G mutation and diabetes mellitus at Seoul National University Hospital. Our cohort comprises 40 patients with MIDD, with a mean age at study enrollment of 33.3±12.9 years and an average % of heteroplasmy of 30.0%± 14.6% in the peripheral blood. The most prevalent comorbidity was hearing loss (90%), followed by albuminuria (61%), seizure (38%), and stroke (33%). We observed a significant negative correlation between % of heteroplasmy and age at diabetes diagnosis. These clinical features can aid in the suspicion of MIDD and further consideration of genetic testing for m.3243A>G mutation.

Maternally inherited diabetes and deafness (MIDD) is a rare mitochondrial disorder primarily resulting from m.3243A>G mutation. The clinical characteristics of MIDD exhibit significant heterogeneity. Our study aims to delineate these characteristics and determine the potential correlation with m.3243A>G heteroplasmy levels. This retrospective, descriptive study encompassed patients with confirmed m.3243A>G mutation and diabetes mellitus at Seoul National University Hospital. Our cohort comprises 40 patients with MIDD, with a mean age at study enrollment of 33.3±12.9 years and an average % of heteroplasmy of 30.0%± 14.6% in the peripheral blood. The most prevalent comorbidity was hearing loss (90%), followed by albuminuria (61%), seizure (38%), and stroke (33%). We observed a significant negative correlation between % of heteroplasmy and age at diabetes diagnosis. These clinical features can aid in the suspicion of MIDD and further consideration of genetic testing for m.3243A>G mutation.