Hemophilia A (HA) is one of the most widespread, X-linked, inherited bleeding disorders, which results from defects in the F8 gene. Nowadays, more than 3500 different pathogenic variants leading to HA have been described. Mutation analysis in HA is essential for accurate genetic counseling of patients and their relatives. We analyzed patients from 273 unrelated families with different forms of HA. The analysis consisted of testing for intron inversion (inv22 and inv1), and then sequencing all functionally important F8 gene fragments. We identified 101 different pathogenic variants in 267 patients, among which 35 variants had never been previously reported in international databases. We found inv22 in 136 cases and inv1 in 12 patients. Large deletions (1–8 exons) were found in 5 patients, and we identified a large insertion in 1 patient. The remaining 113 patients carried point variants involving either single nucleotide or several consecutive nucleotides. We report herein the largest genetic analysis of HA patients issued in Russia.

Book Citations: Authors, Title, HemaSphere, 2023;7(S3):pages. The individual abstract DOIs can be found at https://journals.lww.com/hemasphere/pages/default.aspx. Disclaimer: Articles published in the journal HemaSphere exclusively reflect the opinions of the authors. The authors are responsible for all content in their abstracts including accuracy of the facts, statements, citing resources, etc. 3158 characteristic for gene nor for pseudogene in patient A, and has untouched sequence (i.e. not carrying vWF gene nucleotides) in patient B. Therefore, it was not an exchange of complementary parts of gene and pseudogene, and we cannot suggest any mechanism of conversion in this case. Summary/Conclusion: Gene conversion took place in two cases out of 64, making its frequency in our sample to be 3,13%. The conversed gene allele in the heterozygous state caused mild form von Willebrand disease for patient A and carried only polymorphisms in patient B case. We assumed that gene conversion would be symmetrical, with gene and pseudogene swapping parts. However, it was not confirmed. HemaSphere | 2023;7(S3) EHA2023 Hybrid Congress Copyright Information: (Online) ISSN: 2572-9241 © 2023 the Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the European Hematology Association. This is an open access Abstract Book distributed under the Attribution-NonCommercial-NoDerivs (CC BY-NC-ND) which allows third parties to download the articles and share them with others as long as they credit the author and the Abstract Book, but they cannot change the content in any way or use them commercially. Abstract Book Citations: Authors, Title, HemaSphere, 2023;7(S3):pages. The individual abstract DOIs can be found at https://journals.lww.com/hemasphere/pages/default.aspx.Book Citations: Authors, Title, HemaSphere, 2023;7(S3):pages. The individual abstract DOIs can be found at https://journals.lww.com/hemasphere/pages/default.aspx. Disclaimer: Articles published in the journal HemaSphere exclusively reflect the opinions of the authors. The authors are responsible for all content in their abstracts including accuracy of the facts, statements, citing resources, etc. 3159

Introduction. Von Willebrand disease (vWD) is caused by von Willebrand factor (vWF) dysfunction resulting from pathogenic variants in the vWF gene coding the vWF protein. vWD type 2N is of particular interest, as it is characterized by almost normal vWF antigen level (Ag:vWF) and vWF loss of ability to bind FVIII and protect it from premature clearance, which leads to a low FVIII coagulation activity (FVIII:C). Therefore, the same phenotype occurs in patients with 2N type of vWD and hemophilia A. Aim — to identify patients with 2N type vWD using molecular genetic methods. Methods. Data from the medical histories of vWD patients were used. The major parameter in consideration was FVIII:C to vWF:Ag ratio, which is expected to be below 0.7 in type 2N of vWD. Pathogenic variants in exons and exon-intron junctions of the vWF gene were identified by Sanger sequencing. Due to recessive inheritance of type 2N, verification of the 2N vWD diagnosis required the identification of two pathogenic variants. Results. Three patients were considered as suffering from type 2N of vWD according to hemostasis parameters (FVIII:C/vWF:Ag < 0.7). One patient with a preliminary hemophilia A diagnosis was included after sequencing of the F8 gene, which showed no alterations, so 2N type of vWD was suspected. In all cases, sequencing of the relevant functional regions of the vWF gene led to verification of vWD type 2N. One woman (patient # 4) had a homozygous pathogenic variant p.Arg854Gln (c.2561 G>A) associated with type 2N vWD. One woman (patient # 3) was a compound heterozygote for the pathogenic variant p.Arg816Trp (c.2446 C>T) associated with type 2N and a newly described insertion c.2098_2099insG, that leads to a frameshift. The woman with FVIII:C/vWF:Ag < 0.7 (patient # 1) and the patient # 2 with preliminary hemophilia А diagnosis were both compound heterozygotes for the same combination of pathogenic variants — c.2435delC and p.Thr791Met (c.2372 C>T). Pathogenic variant p.Thr791Met is associated with type 2N, while the deletion c.2435delC should lead to allele disabling. Conclusion. Molecular methods allow more precise differentiation of type 2N from other types of vWD and hemophilia A.

Introduction. Von Willebrand disease (vWD) — one of the most common coagulopathies — is characterised by a rather complicated inheritance pattern, which can be either dominant or recessive depending on the disease type. Aim. To compare clinical, coagulological and molecular genetic data obtained when examining patients with various types of vWD.Materials and methods. The vWF gene exons were sequenced in 16 patients suffering from VWD using the Sanger method.Results. In total, 12 various mutations were identified, one of which (Pro2527His) has not been previously observed in the world population. The c.2435delC microdeletion being a major mutation in many European countries was found to be the most common. This microdeletion was observed in 9 patients, 6 of whom had the most severe recessive form of the disease — type 3 (3 homozygotes). In two patients, this disorder was accompanied by the missense mutation Thr791Met, which allowed the authors to diagnose a rather rare recessive variant of vWD — 2N. In general, the data obtained by molecular genetic analysis correlated with the differential diagnosis of the vWD type, which is based on the clinical picture of the disease and coagulological properties. In only one case, the Arg1374Cys mutation characteristic of type 2 VWD (A/M) was observed in a patient with the alleged type 1 vWD. Most of the mutations were found in exons 18 (mainly c.2435delC deletion) and 28 which makes them the most perspective exons for the mutation search.Conclusion. The search for mutations in the vWF gene should start from exons 18 and 28. The obtained information provides a basis for developing an economical algorithm aimed at searching for mutations in the vWF gene in our counrtry vWD patients.

The genus Sorex is one of the most diverse and ecologically successful lineages of the family Soricidae. We present the first multilocus nuclear phylogeny focusing on the nominal subgenus Sorex s.str., which is distributed mainly in the northern Palearctic. The nuclear tree (six exons) provides more resolution than the mitochondrial data (cytb) and supports subdivision into eight species groups within Sorex s.str., most of which correspond to those recognized from chromosome data. The European species S. alpinus is consistently placed as the basal lineage in the Palearctic clade, while the next split separates the east‐Tibetan group of striped shrews (S. aff. cylindricauda, S. bedfordiae, S. excelsus). Within the remaining species, the following well‐supported clades are identified at the supra‐group level: “araneus” species group+S. samniticus; the “caecutiens” group+the “minutus” group, the latter also including S. minutissimus, S. gracillimus and S. thibetanus. S. raddei and S. roboratus represent separate lineages with no close relatives. The fossil‐calibrated molecular clock placed the divergence between Sorex s.str. and Otisorex at the Early/Middle Miocene boundary. Basal radiation of the crown Sorex s.str. was estimated to have occurred in the middle of the Late Miocene. A more than threefold increase in the diversification rate is inferred for the Early Pliocene. Taxonomic implications including potential genus ranks for Sorex s.str. and Otisorex are discussed. S. alpinus is placed in the monotypic subgenus Homalurus. The full species status of S. buchariensis and S. thibetanus and close relationships between S. cf. cansulus and S. caecutiens are confirmed.

The mitochondrial cytochrome b and nuclear ApoB and RAG2 genes were used to estimate the phylogenetic relationships in Asiatic red-toothed shrews (Soricidae, Episoriculus). Based on molecular data, the genus Episoriculus seems to consist of at least seven valid species: E. baileyi, E. caudatus, E. leucops, E. macrurus, E. sacratus, E. soluensis, and E. umbrinus. Genetic distances among all of them are found to be of 8-16%, with the only low distance (3.4%) being that between E. baileyi and E. leucops. Taiwanese shrew E. fumidus shows high genetic divergence (16-17% for cytb) from other species of Episoriculus. Based on both genetic and morphological data it should be attributed to a separate new genus Pseudosoriculus gen.n. Episoriculus umbrinus was found in Lao Cai Province, representing a new species record for the fauna of Vietnam; morphology-based diagnosis of this specimen has reliably been confirmed by molecular data.