Regulation of gene expression is a complex process. It includes a great number of steps from control of mRNA synthesis to posttranslational modification of proteins. Epigenetic events play essential roles in regulation of transcription. In this review, we concentrate on methylation of DNA as one of the important epigenetic marks. It is well known that DNA methylation is associated with closed chromatin state and, therefore, repressed, inactive genes. Here we describe major processes that depend on DNA methylation: imprinting, X-inactivation, and oncogenesis. Also we describe a number of known methyl-DNA-binding proteins and links between methylation of DNA and higher-order chromatin structure.

Представлена вторая версия руководства по интерпретации данных последовательности ДНК человека, полученных методами массового параллельного секвенирования. Первая версия руководства была опубликована в журнале «Медицинская генетика» в 2017 г. Она основана на рекомендациях и руководяcтвах по интерпретации результатов массового параллельного секвенирования (MPS), разработанных в Европе и США ACMG, CAP, ESHG и FDA. Обсуждение документа было проведено на профильных научных мероприятиях в течение 2017-2018 гг. Поступившие замечания и поправки к документу отражены в его текущей версии. This is a second version of guidelines for the interpretation of massive parallel sequencing (MPS) variants. First version was published in Medical Genetics journal in 2017. They were based on ACMG, CAP, ESHG and FDA guidelines and recommendations. Leading authorities on medical genetics and bioinformatics updated and finalized them. First version of guidelines was presented and discussed on all Russian conference «NGS in medical genetics» and all Russian conference «New technologies for diagnosing hereditary diseases». All members of these conferences and members of Russian Society of Medical Genetics could introduce amendments and give comments. Current version include reviewed notes and comments.

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A pronounced pleiotropic effect of thyroid hormones on the regulation of gene expression in fish in postembryogenesis was demonstrated for the first time using larvae and juveniles of the blue bream Ballerus ballerus as an example. Genome-wide transcriptome sequencing (RNA-seq) identified 1212 differentially expressed genes in the brain and liver of fish kept in triiodothyronine solution (0.25 ng/mL). Our data show that the regulation of gene expression by thyroid hormones is widespread in nature: it involves not only the structural genes but also the regulatory genes. A significant number of genes under the control of thyroid hormones are involved in the determination of morphological traits.

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Aim. To study the associations between genetic polymorphisms and the development of clopidogrel resistance in patients referred for percutaneous coronary interventions (PCI).Material and methods. The study included 84 patients with coronary heart disease (CHD), who underwent planned PCI. Dynamic assessment of platelet aggregation was performed using light transmission aggregometry method (two-channel laser analyser Biola-230LA). The role in the development of inadequate suppression of platelet aggregation during the standard-dose dual antiplatelet therapy (DAT) was investigated for the following genes and polymorphic alleles: CYP2C19 (rs4244285*2, rs4986893*3, rs28399504*, rs56337013*5, and rs12248560*17); CYP2C9 (rs1057910*3); CYP3A4 (rs2242480); CYP2B6 (rs3211371 (5*); CYP3A5 (rs28365083*2 and rs776746); and CYP1A2 (rs762551).Results. The two study groups demonstrated a statistically significant difference in the prevalence of CYP2C19 rs4244285 (2*) polymorphisms, with an increase in GA and AA genotypes and a reduction in the “wild” GG genotype (Χ2 =11,7; р=0,003). The GA genotype was associated with inadequate suppression of platelet aggregation in patients receiving clopidogrel (75 mg/d) and aspirin (300 mg/d; odds ratio 6,27; 95% confidence interval 1,8–21,69). No significant inter-group differences were observed for other polymorphisms (CYP2C9 (rs1057910*3); CYP3A4 (rs2242480); CYP2B6 (rs3211371 (5*)); CYP3A5 (rs28365083*2, rs776746); and CYP1A2 (rs762551)).Conclusion. The degree of platelet aggregation in patients on DAT is related to their genetic status. The assessment of genetic polymorphisms can facilitate the choice of optimal therapeutic strategies in clopidogrel-resistant patients. Patients with the CYP2C192* polymorphism are in particular need for an additional correction of the antiaggregant treatment scheme.

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