Commercially available SARS-CoV-2 RT-qPCR diagnostic tests need obligatory internal validation.

Although infection with severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) does not appear to be as serious a threat to public health as it was in 2020-2021, the increased transmissibility of multiple Omicron descendants may constitute a continuous challenge for health care systems, and reliable detection of new variants is still imperative. This study evaluates the performance of three SARS-CoV-2 diagnostic tests: Novel Coronavirus (2019-nCoV) Real Time Multiplex RT-PCR Kit (Liferiver); Vitassay qPCR SARS-CoV-2 (Vitaassay) and TaqPath COVID­19 CE-IVD RT-PCR Kit (Thermo Fisher Scientific). The analytical sensitivity of the assays as well as their specificity were determined with the use of synthetic nucleic acid standards and clinical samples. All assays appeared to be 100% specific for SARS-CoV-2 RNA in general and the Omicron variant in particular. The LOD determined during this validation was 10 viral RNA copies/reaction for Liferiver and TaqPath and 100 viral RNA copies for Vitassay. We cannot exclude that the LOD for the Vitassay might be lower and close to the manufacturer's declared value of ≥ 20 genome copies/reaction, as we obtained 90% positive results for 10 viral RNA copies/reaction. Mean Ct values at the concentration of 10 viral RNA copies/reaction for the Liferiver, Vitassay and TaqPath kits (35, 37 and 33, respectively) were significantly lower than the cutoff values declared by the manufacturers (≤ 41, ≤ 40 and ≤ 37, respectively). We suggest reporting outcomes based on LOD and cutoff Ct values determined during internal validation rather than those declared by the assays' producers.

Continuity of Y chromosome haplotypes in the population of Southern Poland before and after the Second World War.

The Polish population is reported to be very homogenous as far as Y chromosome polymorphism is concerned. One of the hypotheses that explains this phenomenon is based on the assumption that massive migrations that took place in Poland after the Second World War might have evoked such an effect. Thus, knowledge of the pre-war frequencies of Y chromosome haplotypes in different parts of the country would be a useful tool in testing such a hypothesis. We have collected 226 DNA samples, together with family history data, from males living in the rural area of Malopolska, Polish Southern border region. Based on donors' family histories we were able to reconstruct an 'ancestral' subpopulation of 108 males whose ancestors had inhabited the area before both World Wars. We have analyzed 12 Y-STR loci: DYS19, DYS385, DYS389I&II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438 and DYS439 in all the collected samples. Comparisons of our contemporary and 'ancestral' population samples with other Polish and Central European populations showed that the population of Southern Malopolska is very closely related to other Polish and Slavic populations. The above-mentioned observations suggest that the population of Southern Poland could have been highly homogenous even before the Second World War.

[Correlations between haplogroup membership and Y-STR haplotype as a potential measure of quality control in forensic examinations]. / Zaleznosci pomiedzy przynaleznoscia haplogrupowa a haplotypem Y-STR jako potencjalny element kontroli poprawnosci analiz w medycynie sadowej.

A correlation between particular Y-STR alleles from the so-called "minimal haplotype" and haplogroup membership of the Y chromosome was tested. We collected 146 Y chromosomes from haplogroups R1*, R1a1* and 1* and estimated the frequency of Y-STR alleles in each haplogroup. We then used different algorithms to assign a haplogroup to a haplotype, and tested their accuracy. Generally, a method based on calculation of haplotype similarity using the highest allele frequencies as modal values and assigning a score to each locus based on a ratio of allele frequencies turned out to give the most precise matches. However, using the same rules for Y chromosomes from other populations did not allow for precise estimation of their Y chromosome haplogroup frequencies. Possible explanations for this failure include interpopulation differences in haplotypes correlated with particular haplogroups, as well as a relatively small number of chromosomes analyzed. Potential uses for the presented method in forensics were also described.