[Supratentorial neuroepithelial tumor with PLAGL1 gene fusion - a new type of morphologically variable pediatric brain neoplasm defined by a distinct DNA methylation class. A case report and literature review]. / Supratentorial'naya neiroepitelial'naya opukhol' so sliyaniem gena PLAGL1 u detei ­ novyi tip opukholi mozga s raznoobraznoi morfologicheskoi kartinoi i otlichitel'nym metilyatsionnym profilem(sluchai iz praktiki i obzor literatury).

BACKGROUND: Methylation analysis has become a powerful diagnostic tool in modern neurooncology. This technique is valuable to diagnose new brain tumor types. OBJECTIVE: To describe the MRI and histological pattern of neuroepithelial tumor with PLAGL1 gene fusion. MATERIAL AND METHODS: We present a 6-year-old patient with small right frontal intraaxial tumor causing drug resistant epilepsy. Despite indolent preoperative clinical course and MRI features suggesting glioneuronal tumor, histological evaluation revealed characteristics of high-grade glioma, ependymoma and neuroblastoma. RESULTS: Methylation analysis of tumor DNA confirmed a new type of a recently discovered neoplasm - neuroepithelial tumor with PLAGL1 fusion (NET PLAGL1). PCR confirmed fusion of PLAGL1 and EWSR1 genes. No seizures were observed throughout the follow-up period. There was no tumor relapse a year after surgery. CONCLUSION: Methylation analysis in neurooncology is essential for unclear tumor morphology or divergence between histological and clinical data. In our case, this technique confirmed benign nature of tumor, and we preferred follow-up without unnecessary adjuvant treatment.

[Verification of the diagnosis of supratentorial ependymomas by real-time PCR]. / Verifikatsiya diagnoza supratentorial'nykh ependimom metodom PTsR v rezhime real'nogo vremeni.

BACKGROUND: Differential diagnosis of supratentorial ependymomas is of particular difficulty in neurooncology due to nonspecific clinical and radiographic findings, a rare seen «classic¼ morphological picture, and a nonspecific immunophenotype. Thanks to molecular genetic methods, in particular real-time PCR, it has become possible to verify supratentorial ependymomas and identify their molecular group, on which further prognosis depends. OBJECTIVE: To develop a set of molecular genetic tests based on real-time PCR to verify supratentorial ependymomas. MATERIAL AND METHODS: 56 tissue samples were collected from patients with supratentorial ependymomas, WHO Grade II, and anaplastic ependymomas, WHO Grade III. We developed primers and fluorescent TaqMan probes for real-time PCR analysis to detect the ZFTA::RELA, ZFTA::MAML2, ZFTA::NCOA2, ZFTA::MAML3, YAP1::MAMLD1, and YAP1::FAM118B gene fusions. For immunohistochemical analysis, monoclonal rabbit anti-NF-kb p65 antibodies (HUABIO, China) were used, the study was carried out on AutostainerLink 48 immunostainer (DAKO, Denmark). RESULTS: Real-time PCR was able to verify the diagnosis for 69.9% (n=39) of samples and classify them into molecular groups of ZFTA- or YAP1-positive supratentorial ependymomas. Immunohistochemically it was possible to verify 58% (n=29) ependymomas. CONCLUSION: Diagnosis by real-time PCR is a relatively fast, accessible and easily interpreted method that allows verification of the molecular group in 70% of cases of supratentorial ependymomas without the use of additional methods.

[Astrocytoma with 1p19q codeletion]. / Astrotsitoma s kodeletsiei 1p19q.

Using the example of a recurrent tumor with a 10-year follow-up, the authors show that mutation of the IDH1/2 genes in astrocytomas is not always an early event in the pathogenesis of glioma, that in rare cases a 1p19q codeletion can be found in astrocytomas, and that IDH-mutant tumors can occur in childhood.

[Novel BRAF::EPB41L2 gene fusion in posterior fossa pilocytic astrocytoma. Brief communication]. / Novyi tip sliyaniya genov BRAF::EPB41L2 v piloidnoi astrotsitome zadnei cherepnoi yamki. Kratkoe soobshchenie.

Identification of specific alterations in tumors (as a rule, these are mutations or gene fusions) makes it possible to prescribe targeted drugs of the second line of therapy or, in some cases of inoperable tumors, to observe not only a gradual partial response of the tumor to treatment, but also the removal of these patients from the category of incurable ones. The article describes a new rare type of BRAF::EPB41L2 gene fusion detected in a piloid astrocytoma that developed in the posterior cranial fossa in an 11-year-old boy.

[Sarcomas of the central nervous systems. Clinical observations]. / Sarkomy tsentral'noi nervnoi sistemy. Klinicheskie nablyudeniya.

Here we report three patients with rare primary intracranial sarcomas, two of them were CIC-sarcomas and one was a DICER1-sarcoma. Tumors were examined using DNA methylation. It is important to study of CIC fusions and DICER1 mutations in malignant brain tumors.

[Current diagnostic methods in molecular classification of brain tumors at the Burdenko Neurosurgical Center]. / Sovremennye diagnosticheskie vozmozhnosti molekulyarnogo issledovaniya opukholei mozga v Tsentre neirokhirurgii im. akad. N.N. Burdenko.

DnA methylation has recently been accepted as the most reliable and effective method of diagnosing central nervous system (CNS) tumors. Healthy organs and tumors of different localizations have their own unique methylation structure. Determination of total tumor DNA methylome is the detection of all methylated nucleotides in a tumor. The "gold standard" for analyzing the methylation state of individual cytosines is bisulfite conversion, in which unmethylated cytosines are converted to uracils and read as thymines, while methylated cytosines are protected from conversion.

[A Detection of Allelic Variants at Microsatellite Markers by Using Capillary and Traditional Electrophoresis].

Microsatellite alleles are detected by PCR (polymerase chain reaction) that provides a manifold increase in the number of copies (amplification) of a given DNA fragment. The fragment visualization can be reached by two different methods. These are fragment analysis by capillary electrophoresis in denaturing gel and frag- ment separation in non-denaturing gel with subsequent gel staining. The first method is more accurate and automated, but expensive. The second method is much cheaper but less convenient. It requires manual pro- cessing and is presumably less accurate. In this study, we present the results of comparison of the allele typing at nine microsatellite loci using these two methods for one of the species of Pacific salmon, sockeye salmon Oncorhynchus nerka Walbaum. In most cases, both methods give identical fragment sizes or a constant differ- ence if the alleles are relatively small (not larger than 200-220 bp).

Hybrids between chum Oncorhynchus keta and pink Oncorhynchus gorbuscha salmon: age, growth and morphology and effects on salmon production.

Mature hybrids between chum salmon Oncorhynchus keta and pink salmon Oncorhynchus gorbuscha, which were identified by an intermediate colour pattern, were caught at the Kurilsky Hatchery, Iturup Island, Russia. Most of them were female and 3 years old (a partial freshwater year and 2 marine years), which is intermediate between the ages of maturity of the parental species. The hybrids exceed both parental species in the rate of growth, are large in size and robust and might successfully compete for mating in the wild or be chosen for artificial reproduction. The ratio of the scale length over width, R, is oblate (R < 1), whereas scales of the parental species are prolate (R > 1). From scale analyses, the c.v. in body size of hybrid females at the second marine year is twice that of O. keta, which suggests developmental instability in the hybrid. A dynamic model predicted that continuing hybridization at a low rate does not produce a substantial hybrid load due to selection against advanced-generation hybrids and backcrosses. A high hybridization rate, however, may be an additional risk for genetic management and should be taken into account in programmes of artificial reproduction of Pacific salmon Oncorhynchus spp., although such hybrids might have commercial use in confined production systems.

Efficiency of the inbreeding coefficient f and other estimators in detecting null alleles, as revealed by empirical data of locus oke3 across 65 populations of chum salmon Oncorhynchus keta.

A survey of 65 populations of chum salmon Oncorhynchus keta across the species range revealed homozygote excess (947 homozygotes in 2954 fish) at a polymerase chain reaction (PCR)-based simple sequence repeat (SSR) locus oke3 with multiple alleles, whereas re-designed PCR primers indicated that 328 of these homozygotes were actually heterozygotes. Statistically significant high positive values of inbreeding coefficients, f, in multiple populations appeared to be a reliable predictor of null alleles. Based on these data, three methods were checked for their ability to estimate null-allele frequencies.

[The evolution of microsatellite loci in salmonid fishes].

In ten species of salmonid fishes, sequences of five microsatellite loci were determined. Considerable differences in the structure of the same microsatellites in different species were found. It was demonstrated that the evolution of microsatellites was a complex process, including changes in the copy number, point mutations, and extended deletions and insertions, leading either to the formation of microsatellites or to their loss.

[Microsatellite variation in white-spotted char Salvelinus leucomaenis from Sakhalin Oblast].

A panel of 12 polymorphic microsatellite markers was developed for the population genetic studies of white-spotted char Salvelinus leucomaenis. The four population samples examined consisted of 48 individuals each, and were collected in different geographical regions, including Sakhalin Island, Kunashir Island, and Iturup Island (two samples). The total number of different-sized alleles at different loci varied in the range of 2-31. In the population of white-spotted char subjected to strong anthropogenic pressure allelic diversity and expected heterozygosity indices were found to be lower than in wild populations of this species. The considerable genetic subdivision of different insular populations of white-spotted char observed was consistent with isolation by the distance model.

[A panel of microsatellite loci for population studies of Sakhalin taimen Parahucho perryi (Brevoort)].

Using DNA samples of Sakhalin taimen and a set of microsatellite loci, earlier reported for other salmonid fishes (Salmonidae), successful cross-species amplification was performed. A total of 56 Sakhalin taimen (Parahucho perryi) samples from the Daga, Nabil, Poronai, and Agnevo rivers (Sakhalin Island) were examined at 36 microsatellite loci, most ofwhich were described for other species and first tested in taimen. Among the 21 loci first tested in taimen, two loci produced no amplification products. The remaining 19 loci were successfully amplified (for some loci, new primers were generated). Thirteen of these loci were monomorphic, while six loci were polymorphic and used in further population genetic analysis. In addition, with the purpose of modification of the allele sizes and optimization of the research technique, new primers for the already known 12 loci of Sakhalin taimen were designed. Three more loci were included in analysis without changes. As a result, ajoint panel consisting of 21 polymorphic microsatellite markers was suggested for analysis of Sakhalin taimen. This panel was tested with four population samples from the rivers of Sakhalin Island. The results showed that this panel of markers could be used in detailed population studies for evaluation of the level of genetic differentiation, inbreeding, and migrations in Sakhalin taimen, an endangered species with a fragmented range. Using this approach in further studies will make it possible to isolate basic populations, which is necessary for conservation of this rare species.

[Extension of a set of microsatellite markers for more precise identification of chum salmon (Oncorhynchus keta Walbaum)].

A set often microsatellite loci enabling fairly accurate identification of the chum salmon individuals from geographically distant groups was designed at the Laboratory of Genetic Identification, Vavilov Institute of General Genetics, Russian Academy of Sciences. However, identification of the individuals from closely located basins performed using these loci was not sufficiently precise. The present study was focused on the improvement of the resolution of the method through increasing the number microsatellite loci used. In this study, typing of additional microsatellite loci of chum salmon and evaluation of the change of the degree of identification with the increase of the number ofmicrosatellite loci used is described. It was shown that the identification accuracy permanently increased with the increase of the number of microsatellite markers used.