Objectives: In March 2020, the World Health Organization declared that an infectious respiratory disease caused by a new severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2, causing coronavirus disease 2019 (COVID-19)] became a pandemic. In our study, we have analyzed a large publicly available dataset, the Genome Aggregation Database (gnomAD), as well as a cohort of 37 Russian patients with COVID-19 to assess the influence of different classes of genetic variants in the angiotensin-converting enzyme-2 (ACE2) gene on the susceptibility to COVID-19 and the severity of disease outcome. Results: We demonstrate that the European populations slightly differ in alternative allele frequencies at the 2,754 variant sites in ACE2 identified in the gnomAD database. We find that the Southern European population has a lower frequency of missense variants and slightly higher frequency of regulatory variants. However, we found no statistical support for the significance of these differences. We also show that the Russian population is similar to other European populations when comparing the frequencies of the ACE2 variants. Evaluation of the effect of various classes of ACE2 variants on COVID-19 outcome in a cohort of Russian patients showed that common missense and regulatory variants do not explain the differences in disease severity. At the same time, we find several rare ACE2 variants (including rs146598386, rs73195521, rs755766792, and others) that are likely to affect the outcome of COVID-19. Our results demonstrate that the spectrum of genetic variants in ACE2 may partially explain the differences in severity of the COVID-19 outcome.

(1) Hypophosphatasia (HPP) is a rare inherited disease caused by mutations (pathogenic variants) in the ALPL gene which encodes tissue-nonspecific alkaline phosphatase (TNSALP). HPP is characterized by impaired bone mineral metabolism due to the low enzymatic activity of TNSALP. Knowledge about the structure of the gene and the features and functions of various ALPL gene variants, taking into account population specificity, gives an understanding of the hereditary nature of the disease, and contributes to the diagnosis, prevention, and treatment of the disease. The purpose of the study was to describe the spectrum and analyze the functional features of the ALPL gene variants, considering various HPP subtypes and clinical symptoms in Russian children. (2) From 2014–2021, the study included the blood samples obtained from 1612 patients with reduced alkaline phosphatase activity. The patients underwent an examination with an assessment of their clinical symptoms and biochemical levels of TNSALP. DNA was isolated from dried blood spots (DBSs) or blood from the patients to search for mutations in the exons of the ALPL gene using Sanger sequencing. The PCR products were sequenced using a reagent BigDye Terminator 3.1 kit (Applied Biosystems). Statistical analysis was performed using the GraphPad Prism 8.01 software. (3) The most common clinical symptoms in Russian patients with HPP and two of its variants (n = 22) were bone disorders (75%), hypomyotonia (50%), and respiratory failure (50%). The heterozygous carriage of the causal variants of the ALPL gene was detected in 225 patients. A total of 2 variants were found in 27 patients. In this group (n = 27), we identified 28 unique variants of the ALPL gene, of which 75.0% were missense, 17.9% were frameshift, 3.6% were splicing variants, and 3.6% were duplications. A total of 39.3% (11/28) of the variants were pathogenic, with two variants being probably pathogenic, and 15 variants had unknown clinical significance (VUS). Among the VUS group, 28.6% of the variants (7/28) were discovered by us for the first time. The most common variants were c.571G > A (p.Glu191Lys) and c.1171del (Arg391Valfs*12), with frequencies of 48.2% (13/28) and 11% (3/28), respectively. It was found that the frequency of nonsense variants of the ALPL gene was higher (p < 0.0001) in patients with the perinatal form compared to the infantile and childhood forms of HPP. Additionally, the number of homozygotes in patients with the perinatal form exceeded (p < 0.01) the frequencies of these genotypes in children with infantile and childhood forms of HPP. On the contrary, the frequencies of the compound-heterozygous and heterozygous genotypes were higher (p < 0.01) in patients with infantile childhood HPP than in perinatal HPP. In the perinatal form, residual TNSALP activity was lower (p < 0.0005) in comparison to the infantile and childhood (p < 0.05) forms of HPP. At the same time, patients with the heterozygous and compound-heterozygous genotypes (mainly missense variants) of the ALPL gene had greater residual activity (of the TNSALP protein) regarding those homozygous patients who were carriers of the nonsense variants (deletions and duplications) of the ALPL gene. Residual TNSALP activity was lower (p < 0.0001) in patients with pathogenic variants encoding the amino acids from the active site and the calcium and crown domains in comparison with the nonspecific region of the protein.

The COVID-19 pandemic has drawn the attention of many researchers to the interaction between pathogen and host genomes. Over the last two years, numerous studies have been conducted to identify the genetic risk factors that predict COVID-19 severity and outcome. However, such an analysis might be complicated in cohorts of limited size and/or in case of limited breadth of genome coverage. In this work, we tried to circumvent these challenges by searching for candidate genes and genetic variants associated with a variety of quantitative and binary traits in a cohort of 840 COVID-19 patients from Russia. While we found no gene- or pathway-level associations with the disease severity and outcome, we discovered eleven independent candidate loci associated with quantitative traits in COVID-19 patients. Out of these, the most significant associations correspond to rs1651553 in MYH14p = 1.4 × 10⁻⁷), rs11243705 in SETX (p = 8.2 × 10⁻⁶), and rs16885 in ATXN1 (p = 1.3 × 10⁻⁵). One of the identified variants, rs33985936 in SCN11A, was successfully replicated in an independent study, and three of the variants were found to be associated with blood-related quantitative traits according to the UK Biobank data (rs33985936 in SCN11A, rs16885 in ATXN1, and rs4747194 in CDH23). Moreover, we show that a risk score based on these variants can predict the severity and outcome of hospitalization in our cohort of patients. Given these findings, we believe that our work may serve as proof-of-concept study demonstrating the utility of quantitative traits and extensive phenotyping for identification of genetic risk factors of severe COVID-19.

The formation of biobanks in the structure of scientific and treatment and diagnostic institutions with prospects for interregional integration is a fundamental link in monitoring and predicting diseases of various origins, creating and testing highly effective diagnostics, and developing novel therapeutic agents. Aim . To describe standard operating procedures and principles for the formation of bioresource collections (BRC) in medical institutions with biobanking. Material and methods . The data of scientific and practical biomedical projects using BRC obtained from patients with genetic, multifactorial and infectious diseases in St. Petersburg and Surgut are presented. As of September 2022, the BRC collected on the basis of the Pediatric Research and Clinical Center for Infectious Diseases of the Federal Medical and Biological Agency includes biosamples from 1619 patients, and the BRC collected in the Medical Institute of Surgut State University includes biosamples from 450 patients and healthy individuals of different sex and age. The selection of biosamples from apparently healthy individuals and patients with various diseases can serve as a strategically important resource for future research in terms of etiology, epidemiology, the development of regulatory environment and scales, innovations in the development of diagnostic approaches and treatment of the Russian population.

Human herpes virus 6A (HHV-6A) is able to integrate into the telomeric and subtelomeric regions of human chromosomes representing chromosomally integrated HHV-6A (ciHHV-6A). The integration starts from the right direct repeat (DR_R) region. It has been shown experimentally that perfect telomeric repeats (pTMR) in the DR_R region are required for the integration, while the absence of the imperfect telomeric repeats (impTMR) only slightly reduces the frequency of HHV-6 integration cases. The aim of this study was to determine whether telomeric repeats within DR_R may define the chromosome into which the HHV-6A integrates. We analysed 66 HHV-6A genomes obtained from public databases. Insertion and deletion patterns of DR_R regions were examined. We also compared TMR within the herpes virus DR_R and human chromosome sequences retrieved from the Telomere-to-Telomere consortium. Our results show that telomeric repeats in DR_R in circulating and ciHHV-6A have an affinity for all human chromosomes studied and thus do not define a chromosome for integration.

Purpose: To characterize clinical and laboratory features of infectious mononucleosis (IM) of EBV and HHV-6 etiology among children. Material and methods. A single-center prospective study was performed at Pediatric Research and Clinical Center for Infectious Diseases in 2021 — 2022, which included 84 patients with IM EBV (n = 40), HHV-6 (n = 11), EBV + HHV-6 (n = 33). Methods of laboratory diagnostics were clinical, biochemical blood tests, qualitative and quantitative PCR of blood (whole blood, plasma) to herpesvirus 4—6 types. Results. Patients with EBV IM were significantly older than children with HHV-6 IM and EBV + + HHV-6 IM (р ≤ 0,004). The main complaint of patients was fever (median 39,0°С, Q1—Q3 38,5—39,3°С). Nasal stuffiness (93%), tonsillitis (86%), peripheral cervical lymphadenopathy (100%) dominated among clinical manifestations in all groups. Splenomegaly was noted more rarely than hepatomegaly in children. There were no significant differences in the level of leukocytes among patients (р > 0,05). Increased values of lymphocytes, atypical mononuclear cells, hepatic cytolysis syndrome were characteristic of EBV-monoinfection (р ≤ 0,007). On the contrary, level of neutrophils was significantly higher in the HHV-6 IM group. Genotype HHV-6B was detected in 100% of cases. Assay of EBV viral load showed following: this indicator in plasma (р = 0,0008) and whole blood (р = 0,028) in EBV patients was significantly higher than among EBV + HHV-6 IM. A direct moderate correlation was found between viral loads in different human fluids (r = 0,413, р < 0,05). Conclusions. The results emphasize the importance of clinical and etiological diagnosis, including HHV-6 determination, for the well-timed registration of children with IM and their coverage with regular medical check-up.